Launch of Astrosat

On Sept 28, ISRO launched India’s Astrosat observatory into its planned 600 km, 6 degree inclination orbit. The observatory comprises four X-ray telescopes, and two for UV and blue wavelengths. All instruments are co-aligned, and work simultaneously. Canada has a 5% time-share for providing the solar-blind detectors for UVIT – the UltraViolet Imaging Telescopes. The instruments are all operating, and the mission is in a 6-month period of commissioning and automating of operations. Instrument team demonstration-science observations will be released in April 2016, and team observations will continue until proposal-time observing begins in September. A call for the first Canadian proposals will be issued in ~March, and these may request observations from all instruments. CSA are funding an expert to support Canadian proposals and data processing for UVIT.

NGC 2336 - UVIT, NUV channel, res. = 1.2 arcsec.

NGC 2336 – UVIT, NUV channel, res. = 1.2 arcsec.

Astrosat offers a new and unique facility for Canadian research, and its performance appears to be excellent. UVIT in particular offers wide-field imaging in 3 simultaneous wavelength channels, with ~1” resolution, and a suite of filters and gratings. More
information may be found at this site.

The first UVIT observations were made on Dec 1, following a planned interval to allow for full outgassing. The operations efficiency and data handling are being ramped up slowly, as is normal for a complex space observatory, but the spacecraft and instruments are working well, in some cases exceeding specifications.

Submitted by John Hutchings
(Cassiopeia – Hivers/Winter 2015)

BRITE-Constellation News

Submitted by Gregg Wade
(Cassiopeia – Hivers/Winter 2015)

Introduction

BRITE-Constellation (where BRITE stands for BRIght Target Explorer) is a network of five nanosatellites operating in low Earth orbit, designed to explore the properties of the brightest stars in the night sky.

Figure 1 - The mission patch of the BRITE-Constellation mission.

Figure 1 – The mission patch of the BRITE-Constellation mission.

The BRITE mission is supported by three countries — Canada, Austria and Poland — where Canadian funding comes mainly from the Canadian Space Agency (CSA) and the prime contractor is the University of Toronto Institute for Aerospace Studies – Spaceflight Laboratory (UTIAS-SFL). The mission was planned to have 6 BRITE nanosats, a pair from each partner country, but one of the Canadian nanosats did not detach from the third stage of its launch vehicle.

Each BRITE nanosat (mass = 7 kg; dimensions 20 × 20 × 20 cm) has a 3-cm optical telescope feeding a CCD detector. The Constellation was designed to monitor photometrically through blue and red filters the brightness and temperature variations of stars generally brighter than V ~ 4 with precision, cadence and time coverage not possible from the ground. Each BRITE instrument has an enormous field-of-view: 24° square, large enough to encompass the entire constellation of Orion (but at a resolution of only about half an arcminute per pixel). That means BRITE-Constellation can collect data on several dozens of stars simultaneously.

The sample of the apparently brightest stars in the night sky is a sample dominated by the most intrinsically luminous stars in the Galaxy: hot massive stars at all evolutionary stages, and evolved intermediate-mass stars at the very end of their nuclear-burning phases. The main goals of BRITE-Constellation are to (1) measure the frequencies of pulsations (both acoustic and gravity modes) to probe the interiors and ages of stars through asteroseismology; (2) measure the rotational modulation of stars due to star spots carried across their disks; (3) search for exoplanets through transits; and (4) obtain light curves of massive eclipsing binaries. While goal (2) is often associated with cool solar-type stars, spots in the photospheres of luminous stars could be the sources of co-rotating interaction regions in the winds, possibly arising from magnetic subsurface convection in hot, massive stars.

Figure 2 - Hertzsprung-Russell diagram of the stars of brightest  apparent magnitude, V<4.5. These ∼ 600 stars are the primary BRITE targets.

Figure 2 – Hertzsprung-Russell diagram of the stars of brightest apparent magnitude, V<4.5. These ∼ 600 stars are the primary BRITE targets.

To develop the optimum data processing and reduction strategies, a BRITE Photometry Tiger Team (PHOTT) was assembled. PHOTT explored and compared various pipelines and ways to minimise data artifacts. To extract the maximum scientific value from the reduced BRITE photometry, the BRITE Ground-Based Observation Team (GBOT) organizes ground-based observing campaigns, primarily high-resolution, high-S/N spectroscopy of BRITE targets.

A detailed overview of the scientific motivation of the mission, and technical aspects of the system, are provided by Weiss et al. (2015, PASP 126, 573).

Mission Status and Data Releases

Five of the planned six BRITE nanosats are currently operating in low-altitude (600-800 km) orbits. The first pair of BRITE nanosats (from Austria) were launched on 25 Feb 2013, and the Canadian BRITEs were launched in August 2014 aboard a Russian rocket. The sixth satellite currently remains unusable in a higher elliptical orbit due to a malfunction in the release mechanism of the Russian rocket third stage.

A new ground station capability has been developed at UBC and will soon come on-line, permitting greater data downlink capability.

Figure 3 - The two Canadian BRITE nanosatellites (named "BRITE-Montreal", blue filter and "BRITE-Toronto", red filter), at UTIAS-SFL prior to shipment in 2014.

Figure 3 – The two Canadian BRITE nanosatellites (named “BRITE-Montreal”, blue filter and “BRITE-Toronto”, red filter), at UTIAS-SFL prior to shipment in 2014.

Seven data releases to BRITE Target PIs have occurred so far. The first was a set of science commissioning data, including (1) about 5 months of quasi-continuous observation of 15 stars in Orion. Subsequent releases were 6-month campaigns of fields in (2) Centaurus and Lupus (30 stars), (3) Sagittarius (18 stars), (4) Cygnus (37 stars), and (5) Perseus (31 stars) . (6) Orion was observed again. Most recently, a field (7) in Vela and Puppis was observed (20 stars). Very soon, data from the recently-completed Scorpius, Cygnus-II and Cassiopeia/Cepheus fields will also be released.

The first BRITE science results have been accepted in refereed journals: a paper by Weiss et al. on the pulsating magnetic star alpha Cir. Weiss et al. (A&A, in press) report two-colour BRITE photometry of this roAp star, excluding quadrupolar modes for the main pulsation frequency, and reporting remarkable differences in the rotationally-modulated flux in the blue and red bandpasses.

Additional papers reporting results for hot, pulsating stars and classical Be stars have also recently been submitted for publication.

The first BRITE science conference, “Science with BRITE Constellation: Initial Results” took place during 14 – 18 September 2015 in Gdansk Sobieszewo, Poland. Presentations authorised for public release are available on the conference website.

A workshop related to a large-scale spectropolarimetric survey of BRITE targets was held at the Meudon
Observatory on October 26-30, with 19 participants. The BRITE spectropolarimetric survey is proceeding nominally, with expected completion in March 2016. Magnetic field has been detected in 47 stars so far, and follow-up observations are being acquired or planned for many of them. Two papers have already been published (Shultz et al. 2015, Neiner et al. 2015) and many others are in preparation. A second BRITE spectropolarimetric workshop will be organized from 14-18 November 2016 at the Meudon Observatory near Paris.

Figure 4 - Light curves of the eclipsing binary V Pup, observed as part of the BRITE Vela/Puppis field. Shown here is a 5-day interval of the BRITE-Austria (blue) and BRITE-Toronto (red) observations.

Figure 4 – Light curves of the eclipsing binary V Pup, observed as part of the BRITE Vela/Puppis field. Shown here is a 5-day interval of the BRITE-Austria (blue) and BRITE-Toronto (red) observations.

Mission Management and Contact

Executive decisions about the mission are made by the BEST (BRITE Executive Science Team), consisting of representatives from all three partner nations. The Canadian BEST members are Tony Moffat (BEST Chair, Université de Montréal), Jaymie Matthews (BEST vice-Chair, UBC), Slavek Rucinski (University of Toronto), and Gregg Wade (Royal Military College), with Jason Rowe (Université de Montréal) and Stefan Mochnacki (University of Toronto) serving as non-voting BEST members.

Setting priorities on BRITE targets and science goals was overseen by BEST, with input from the BRITE International Science Advisory Team (BIAST), consisting of 130 astronomers around the globe. Interested in joining BIAST, to participate in data analysis, and receive monthly mission updates? Please contact BEST through Tony Moffat (moffat@astro.umontreal.ca).

Neiner, C.; Buysschaert, B.; Oksala, M.E.; Blazère, A., 2015, “Discovery of two new bright magnetic B stars: i Car and Atlas”, MNRAS 454, 56

Shultz, M.; Rivinius, Th.; Folsom, C. P.; Wade, G. A.; Townsend, R. H. D.; Sikora, J.; Grunhut, J.; Stahl, O.; and the MiMeS Collaboration, “The magnetic field and spectral variability of the He-weak star HR 2949″, 2015, MNRAS 449, 3945

Weiss, W.W.; Rucinski, S.M.; Moffat, A.F.J.; Schwarzenberg-Czerny, A.; Koudelka, O.F.; Grant, C.C.; Zee, R.E.; Kuschnig, R.; Mochnacki, St.; Matthews, J.M.; Orleanski, P.; Pamyatnykh, A.; Pigulski, A.; Alves, J.; Guedel, M.; Handler, G.; Wade, G.A.; Zwintz, K., 2014, “BRITE-Constellation: Nanosatellites for Precision Photometry of Bright Stars”, PASP 126, 573.

Weiss, W.W.; Frohlich, H.-E.; Pigulski, A.; Popowicz, A.; Huber, D.; Kuschnig, R.; Moffat, A.F.J.; Matthews, J.M.;, Saio, H.; Schwarzenberg-Czerny, A.; Grant, C; Koudelka, O.; Lueftinger, T.; Rucinski, S.; Wade, G.A.; Alves, J.; Guedel, M.; Handler, G.; Mochnacki, S.; Orleanski, P.;, Pablo, B.; Pamyatnykh, A.; Ramiaramanantsoa, T; Rowe, J.; Whittaker, G.; Zawistowski, T.; Zoconska, E.; Zwintz, K., 2015, “The roAp star alpha Cir seen by BRITE-Constellation”, A&A, in press.

Herschel-HIFI News

Submitted by Sylvie Beaulieu, Herschel-HIFI Instrument Support Scientist
(Cassiopeia – Hivers/Winter 2015)
Herschel_spacecraft_artist410

Herschel Science Archive (HSA)

The latest Herschel Science Archive (v.7.0) was released on 28 October 2015. In this release, you will find links from individual observations to associated refereed publications. This new feature is accessible from the query result page in the HSA User Interface by selecting the “DETAILS & PUBLICATIONS” button, and then clicking on the tab “Publications”. Footprints for photometric observations (PACS & SPIRE) greatly improve the accuracy of geometrical searches. Remember that Herschel data are 100% in the public domain.

University of Waterloo Group News

Since last August, the group has welcomed a new member, Dr Scott Jones, who is a recent PhD graduate from Western University. Scott is helping with HIFI data processing and analysis.

Please note that the Herschel-HIFI Waterloo group will cease operation by the 31st of March 2016. Although no support will be available from that date via the Waterloo group, we will try to maintain the webpage and keep it as up-to-date as possible.

The implementation of the Herschel Explanatory Legacy Library (HELL) is progressing well. A special one-week documentation retreat was held in October to allow a group of eight HIFI editors to concentrate on editing the HIFI Handbook, and several other documents that will join the HELL documentation repository. Permanent links to the ESA Herschel Project and to the Herschel Explanatory Legacy Library will be available through our webpage.

Herschel Interactive Processing Environment (HIPE)

While HIPE 13.0 is the current release, and HIFI_CAL_22_0 is the latest Calibration Tree, this autumn saw the last Astronomer Acceptance Testing for HIPE, with HIPE 14.0 due to be released to the community in mid-December 2015. HIFI_CAL_24_0 will also be released. We invite you to visit What’s New in HIPE for the changes in this new release and see below. Additional information can be found in the HIFI Instrument and Calibration page

HIFI Calibration

A new calibration tree has been implemented in HIPE 14.0. It contains substantial changes in the sideband ratio tables, as well as a complete intensity calibration uncertainty component model. The corresponding UncertaintyTable products are available in calibration -> Downlink -> Generic and were updated with the following uncertaintyType: HotLoadTemp, ColdLoadTemp, HotLoadCoupling, ColdLoadCoupling, SidebandRatio, OpticalStandingWavesLoads, OpticalStandingWavesDiplexer.

The new calibration tree also provides tables of spur warning channel flags for point and mapping modes. These flags are assigned based on a knowledgebase built out of the spur flags manually identified for spectral scans and populated in the calibration tree in HIPE 13.0.

The sideband ratio updates will imply changes in intensity at all frequencies in bands 1 to 4. No changes are expected in bands 5 to 7.

The identifyLines task was updated with the following: implementation of threading to speed up the task, improvements of the rejection of false detected lines, changes on the Herschel Spectral Line List columns names, implementation of the image band line identification for pointed and mapping observations, fix to the RMS computation, and the implementation of the exportLines task.

Level 2 Pipeline

For DBS Raster maps, the Level 2 spectra are no longer averaged – this was already the case for OTF maps; Introduction of a new calibration output providing a frequency-dependent intensity calibration uncertainty budget; Assignment of spur warning channel flag for all point and mapping modes.

Level 2.5 Pipeline

Changes to the output of the Deconvolution task: the single-sideband spectrum is now contained in a Spectrum1d called “dataset” (it was called “ssb” up to HIPE 13).

HIFI products

Flags are now applied to OFF spectra as well; Generation of a browse image for the reference spectra, when the option useReferenceSpectra is set to true; The FITS header keywords have been revamped in order to provide proper nicknames to the parameters featured in those headers.

Standing Wave removal

New parameter addMedianContinuum: allow the median continuum to be added back into the baseline fit flux [DEFAULT: False].

Baseline removal

New parameter addMedianContinuum: allow the median continuum to be added back into the baseline fit flux but only performs well for basemode=’sub’ and not basemode=’div’ [DEFAULT: False].

Deconvolution

The output deconvolution product ssb is now called dataset (please note that scripts prior to this change will break).

HiClass Export tool

Although this is not an HCSS development, it should be noted that GILDAS/Class now reads the HCSS-generated FITS without needing any prior conversion as it used to be the case using the HiClass task.

Documentation

With this latest release, you have access to the latest documentation updates for both the HIFI Data Reduction Guide, and the HIFI Pipeline Specification Manual. Specifically, you will find a revamp of the chapter “Flags in HIFI data”, section Quality Flags, and a new chapter called “Understanding the uncertainty table information in your data” has been added to the HIFI Data Reduction Guide.

Conferences, workshops and webinars related to Herschel

The University of Waterloo Herschel-HIFI Support Group is committed to assisting you with accessing data through the Herschel Science Archive (HSA) and in using the Herschel Interactive Processing Environment (HIPE) to process your data. Please do not hesitate to contact us. Our webpage has a dedicated page on Data Processing.

Maunakea Spectroscopic Explorer (MSE) Update

Submitted by Patrick Hall, MSE Advisory Group member
(Cassiopeia – Hivers/Winter 2015)

mse-logo2Design work for the Maunakea Spectroscopic Explorer (MSE) continues apace.

The MSE Science Requirements Document

The MSE Science Requirements Document (SRD) was formally configured in October after a 12 month effort by the international science team to revisit the basic science drivers of the facility and identify the key science enabling capabilities. The SRD is the top level requirement document that gives a clear direction for the conceptual design phase; all other technical documents flow from the SRD. Engineers are therefore working to the requirements set out in this document, and changes to it are made through a formal review and approval process.

The SRD will shortly be available for download at the “Documents” page of the MSE webpages. In parallel, an exposure draft of the Detailed Science Case – providing the scientific narrative of the science cases and context from which the SRD has been derived – is being finalised and will be available for download in the first quarter of 2016.

Activities of MSE’s International Engineering Team

MSE’s International Engineering Team met for a second time, on 14-16 October 2015 at the original Paris Observatory. This meeting was graced by a number of new participants, including those from Spain, Lausanne Switzerland, Durham England, Lyon France and Meudon France. The workshop included discussion of the overall system architecture and the work packages designing the major subsystems.

Discussions at CFHT’s board meeting

This month’s CFHT Board meeting includes a full afternoon session devoted to MSE. Discussion will include the design work distribution, plans for science case review, operations planning, engineering status, budget and resources, and governance models.

Spain interested in joining the MSE collaboration

Spain, as represented by Consejo Superior de Investigaciones Científicas (CSIC) and Instituto de Astrofísica de Canarias (IAC), have recently expressed a strong interest in joining the MSE collaboration. Letters of collaboration are expected imminently. Furthermore, Spain has offered to host the next MSE Team Collaboration Workshop, at La Palma. More details in the next Cassiopeia!

CFI proposal plans

A CFI proposal is being planned to support strong Canadian participation in the design and construction of MSE instruments and subsystems. If you are interested in being part of such a proposal and haven’t already been contacted, please contact Patrick Hall at yorkphall@gmail.com.

Web sites

MSE Website
MSE Overview

Nouvelles du CNRC Herzberg/NRC Herzberg News

By/par Dennis Crabtree (NRC-Herzberg)
with contributions from/avec des contributions de Chris Willott

(Cassiopeia – Hivers/Winter 2015)

La version française suit

These reports will appear in each issue of Cassiopeia with the goal of informing the Canadian astronomical community on the activities at NRC Herzberg.

Feedback is welcome from community members about how NRC Herzberg is doing in fulfilling our mandate to “operate and administer any astronomical observatories established or maintained by the Government of Canada” (NRC Act).

Canadian Time Allocation Committee (CanTAC)

CanTAC met in October/November by a series of telecons to discuss and rank CFHT and Gemini proposals for semester 2016A. The CanTAC SuperChair for this meeting was Kristine Spekkens (RMC), while the Galactic panel chair was Stanimir Metchev (Western) and the Extragalactic panel chair was Scott Chapman (Dalhousie). Dennis Crabtree continues to serve as the technical secretary.

The full list of CanTAC members for the November meeting was:

Galactic Extragalactic
David Bohlender (Herzberg) Arif Babul (Victoria)
Christopher Johns-Krull (Rice) Peter Capak (Caltech)
Stanimir Metchev (Western) Scott Chapman (Dalhousie)
Leslie Rogers (Caltech) Alan McConnachie (NRC Herzberg)
Samar Safi-Harb (Manitoba) Kristine Spekkens (RMC)
Ingrid Stairs (UBC) Ludo van Waerbake (UBC)
Peter Stetson (Herzberg)

For Semester 2016AB CanTAC received 40 CFHT proposals (25 Galactic and 15 Extragalactic) and 46 Gemini proposals (26 Galactic and 20 Extragalactic). There was a total of 615 hours requested on CFHT and 606 hours on Gemini. The subscription rates were 2.73 for CFHT, 2.6 for Gemini North and 3.2 for Gemini South.

The demand for both telescopes increased significantly from the last semester although the trend of receiving more Galactic than Extragalactic proposals continues. CanTAC felt the quality of proposals was quite high this semester.

CADC

The CADC developed the CANFAR (Canadian Advanced Network for Astronomical Research) computing infrastructure system for astronomers. CANFAR provides its users easy access to very large resources for both storage and processing, using a cloud based framework. The current system uses a mix of internal CADC resources and Compute Canada’s national computing resources to store and make available approximately a Petabyte of observational data, as well as significant computing resources.

NRC Herzberg received NRC investment money to enable the transfer of the bulk of the hardware and service needs of the CANFAR Network Enabled Platform from NRC-Herzberg to Compute Canada. The CADC has worked with Compute Canada to develop a detailed statement of work for the CADC/CANFAR/CC Transition Project (C3TP). This is a shared co-development project in which Compute Canada will develop generic cloud and data services which can be used by a suitably modified CANFAR system to provide specific functionality to CADC’s community. The CADC will work with Compute Canada to design these generic services.

JWST

The Canadian FGS/NIRISS leads discussing detector tuning data at the JWST Cryo-Vacuum 3 Test at Goddard Space Flight Center, Maryland in November 2015. From left to right, René Doyon (FGS/NIRISS Principal Investigator, Université de Montréal), Begoña Vila (CV3 Test Lead, NASA), Chris Willott (FGS/NIRISS Instrument Scientist, NRC) and Neil Rowlands (FGS/NIRISS Project Scientist at COM DEV International).

The Canadian FGS/NIRISS leads discussing detector tuning data at the JWST Cryo-Vacuum 3 Test at Goddard Space Flight Center, Maryland in November 2015. From left to right, René Doyon (FGS/NIRISS Principal Investigator, Université de Montréal), Begoña Vila (CV3 Test Lead, NASA), Chris Willott (FGS/NIRISS Instrument Scientist, NRC) and Neil Rowlands (FGS/NIRISS Project Scientist at COM DEV International).

It is an exciting time in the JWST project with activities on several fronts in the integration and testing phase of the observatory development. The four science instruments are midway through the third and final Cryo-Vacuum Test (CV3) at NASA’s Goddard Space Flight Center, Maryland. This 3 month long test at 40K simulates the conditions of the observatory in orbit, putting the instruments through a series of thermal, electrical and optical tests to provide flight-like data for verification and calibration. The Canadian FGS/NIRISS instrument team from the Université de Montréal, National Research Council, Canadian Space Agency, Space Telescope Science Institute and prime contractor COM DEV International are heavily involved in supporting these tests which run 24/7 for the 3 month period. At the time of writing, activities are progressing well and on schedule.

Another exciting event taking place now is the integration of the 18 primary mirror segments onto the telescope structure. Each hexagonal segment is made of lightweight beryllium with a very thin gold coating and measures 1.3 metres across. A robotic arm is used to lift and position each mirror. All 18 primary segments and the secondary mirror will be in place early in 2016. After that the fully-verified instrument module is to be installed onto the telescope.

In October 2015 the European Space Agency hosted a conference titled “Exploring the Universe with JWST”. This meeting brought together scientists from around the world to discuss how JWST will be used to tackle their science questions. Presentations can be found online at www.cosmos.esa.int/web/jwst/conferences/jwst2015 .

There is also a lot going on with the JWST ground system, in particular the pipeline, calibration and commissioning plans for the science instruments. The Canadian team is very active in all these areas to ensure that the powerful science modes of NIRISS are capitalized upon. With parallel observing now approved by the project, significant work is underway to see how NIRISS can be used in parallel to significantly enhance the efficiency of the observatory.

JWST will be launched into a halo orbit around L2 on an Ariane V rocket in October 2018.



Les rubriques qui suivent reviendront dans chaque numéro du bulletin et ont pour but de tenir les astronomes canadiens au courant des activités de CNRC Herzberg.

Les commentaires des astronomes sur la manière dont CNRC Herzberg accomplit sa mission, c’est-à-dire « assurer le fonctionnement et la gestion des observatoires astronomiques mis sur pied ou exploités par l’État canadien » (Loi sur le CNRC), sont les bienvenus.

Comité canadien d’attribution du temps d’observation (CanTAC)

Les membres du CanTAC se sont entretenus en octobre/novembre dans le cadre d’une série de téléconférences afin d’examiner et d’ordonner les demandes du semestre 2016A se rapportant aux observatoires TCFH et Gemini. Kristine Spekkens (RMC), qui agissait à titre de super-présidente à cette occasion, était appuyée par Stanimir Metchev (Western) à la tête du Groupe galactique et Scott Chapman (Dalhousie) à la tête du Groupe extragalactique. Dennis Crabtree continue de servir de secrétaire technique au Comité.

Voici la liste complète des membres du CanTAC qui ont assisté à la réunion de novembre :

Groupe galactique Groupe extragalactique
David Bohlender (Herzberg) Arif Babul (Victoria)
Christopher Johns-Krull (Rice) Peter Capak (Caltech)
Stanimir Metchev (Western) Scott Chapman (Dalhousie)
Leslie Rogers (Caltech) Alan McConnachie (NRC Herzberg)
Samar Safi-Harb (Manitoba) Kristine Spekkens (RMC)
Ingrid Stairs (UBC) Ludo van Waerbake (UBC)
Peter Stetson (Herzberg)

Le CanTAC a reçu 40 demandes pour le TCFH (25 du Groupe galactique et 15 du Groupe extragalactique), pour le semestre 2016B, et 46 pour l’observatoire Gemini (26 du Groupe galactique et 20 du Groupe extragalactique), ce qui correspond à un total de 615 heures dans le premier cas et de 606 heures dans le second. Les taux d’adhésion étaient de 2,73 pour le TCFH, de 2,6 pour Gemini Nord et de 3,2 pour Gemini Sud.

La demande de temps d’observation aux télescopes a sensiblement augmenté comparativement au semestre précédent, bien que l’on continue de recevoir plus de requêtes du Groupe galactique que du Groupe extragalactique. Le CanTAC estime que les demandes soumises ce semestre se démarquaient par leur très grande qualité.

CCDA

Le CCDA a mis au point l’infrastructure informatique CANFAR (réseau évolué du Canada pour la recherche en astronomie) destinée aux astronomes. CANFAR permet à ses utilisateurs d’accéder aisément à de très vastes ressources de stockage et de traitement des données par l’infonuagique. Le système actuel combine les ressources internes du CCDA et les installations nationales de Calcul Canada pour entreposer environ un pétaoctet d’observations et les mettre à la disposition des chercheurs, avec d’importantes ressources en calcul.

CNRC Herzberg a obtenu des fonds du CNRC pour que le gros des besoins en matériel et en services de la plateforme qu’habilite le réseau CANFAR soit confié à Calcul Canada. De concert avec cet organisme, le CCDA a élaboré un énoncé des travaux détaillé pour le projet de transition CCDA/CANFAR/CC (PTC3), projet de développement conjoint en vertu duquel Calcul Canada mettra au point des services de données et d’infonuagique génériques auxquels on accédera par le système CANFAR après son adaptation, et qui offriront des fonctionnalités précises aux membres du CCDA. Le CCDA collaborera avec Calcul Canada pour créer les services génériques en question.

JWST

Novembre 2015: le noyau de l’équipe FGS/NIRISS discute des ajustements de détecteur dans le cadre de la troisième campagne de tests (CV3) des instruments du JWST qui ont cours au Goddard Space Flight Centre de la NASA (MD, É.U). Dans l’ordre habituel, René Doyon (chercheur principal du FGS/NIRISS; Université de Montréal), Begoña Vila (leader des tests CV3, NASA), Chris Willott (scientifique responsable de l’instrument FGS/NIRISS; NRC-H) et Neil Rowlands (scientifique responsable du projet FGS/NIRISS chez COM DEV International).

Novembre 2015: le noyau de l’équipe FGS/NIRISS discute des ajustements de détecteur dans le cadre de la troisième campagne de tests (CV3) des instruments du JWST qui ont cours au Goddard Space Flight Centre de la NASA (MD, É.U). Dans l’ordre habituel, René Doyon (chercheur principal du FGS/NIRISS; Université de Montréal), Begoña Vila (leader des tests CV3, NASA), Chris Willott (scientifique responsable de l’instrument FGS/NIRISS; NRC-H) et Neil Rowlands (scientifique responsable du projet FGS/NIRISS chez COM DEV International).

Le projet JWST traverse un moment palpitant, car les activités se multiplient sur plusieurs fronts dans la phase d’intégration et d’essais de l’observatoire. Les quatre instruments scientifiques en sont à mi-chemin du troisième et dernier essai cryogénique sous vide (CV3) au Goddard Space Flight Center de la NASA, au Maryland. Cette épreuve de trois mois, réalisée à la température de 40 K, simule les conditions d’un observatoire spatial, ce qui obligera les instruments à subir une batterie de tests thermiques, électriques et optiques, et à fournir des données semblables à celles qui seront acquises en orbite, en vue de leur vérification et d’un étalonnage. L’équipe de l’instrument canadien FGS/NIRISS, composée de membres de l’Université de Montréal, du Conseil national de recherches, de l’Agence spatiale canadienne, du Space Telescope Science Institute et de COM DEV International, le maître d’œuvre, est fortement impliquée dans ces tests qui dureront trois mois, sans interruption. Au moment où j’écris ceci, les activités progressent bien et aucun retard n’a été enregistré.

Un autre fait fort intéressant en train de se produire concerne l’intégration des dix-huit éléments du miroir primaire à l’armature du télescope. Mesurant 1,3 m de diamètre, chaque partie hexagonale du miroir est composée de béryllium, métal très léger, et recouvert d’une mince couche d’or. Un bras robotisé soulève et place chaque élément. Les 18 sections du miroir primaire et le miroir secondaire devraient être en place au début de 2016. Suivra l’installation du module instrumental, après les vérifications d’usage.

En octobre 2015, l’Agence spatiale européenne organisait un colloque qui avait pour thème l’exploration de l’univers avec le JWST. Des scientifiques du monde entier y ont assisté, anxieux de savoir comment on utiliserait le JWST pour répondre à leurs questions. Les exposés donnés au colloque peuvent être consultés au www.cosmos.esa.int/web/jwst/conferences/jwst2015.

Beaucoup de choses se passent également du côté des installations terrestres du JWST, notamment le pipeline, l’étalonnage des instruments scientifiques et les plans en vue de leur mise en service. L’équipe canadienne s’active fort dans tous ces domaines pour s’assurer qu’on exploitera toute la puissance des modes scientifiques du NIRISS. Les observations en parallèle ayant désormais été autorisées dans le cadre du projet, on a entrepris d’importants travaux pour établir si le NIRISS pourrait être utilisé en parallèle afin de rehausser sensiblement l’efficacité du télescope.

Le JWST sera lancé sur son orbite en halo autour de L2 avec une fusée Ariane V en octobre 2018.

President’s Report

Wison

By Chris Wilson, CASCA president
(Cassiopeia – Hivers/Winter 2015)

Hi, everyone,

Well, the end of term is in sight but like many of you, I am still swamped with marking and student meetings. So this will again be a short report noting a few important highlights.

Our next annual meeting will be held in Winnipeg, Manitoba. The graduate student workshop will be on May 30th, 2016 with the CASCA meeting itself May 31st – June 2nd, 2016. The meeting will be held at the historic Fort Garry Hotel, located in the heart of Winnipeg, within easy walking distance of many attractions such as The Forks and the Canadian Museum for Human Rights. More information is available on the meeting web site. Registration will open in January.

Work on the report from the Mid-Term Review panel is well underway; the committee estimates that roughly 90% of the document has been written. The panel is holding weekly telecons and I think the report is converging quite quickly. While there is a certain amount of polishing that will be needed, the panel is working to have the full report completed early in the new year.

I am sure that many of you continue to follow the latest news on the TMT from Hawai`i. In early December, the Hawai`i Supreme Court invalidated the Conservation District Use Permit issued by the Board of Land and Natural Resources (BLNR) to the University of Hawaii – Hilo to build TMT on Maunakea. This means that TMT will need to apply for a new permit in Hawai`i in order to build on the Maunakea site, with September 2016 the earliest possible date on which a new permit could be obtained. We continue to monitor the situation and will share information as it becomes available and can be made public.

Members of the ACURA Advisory Committee on the SKA helped to organize a workshop on “Canada and the SKA” that was held at the University of Toronto December 10-11, 2015. The meeting was an opportunity for the Canadian community to assess its main interests and activities for the SKA, and to identify areas for synergy and coordination. There was good turnout by astronomers from a number of Canadian universities and NRC-Herzberg, as well as participation by a number of potential industrial partners and a number of international astronomers as well. If you missed the workshop, the talks are expected to be made available soon on the conference web site.

The CASCA Board held two meetings this fall, a short one in October and our longer mid-year meeting in December. These meetings are held electronically to save time and travel costs. We also discuss issues as they arise via email and igloo (a community forum software). The new Diversity and Inclusivity Committee has been established; its first chair is Dr. Brenda Matthews from NRC-Herzberg and you can find the membership and terms of reference on the CASCA web site. Another task at this time of year is identifying new members to serve on CASCA committees: a big thank you to everyone who has agreed to serve our community in this way!

One of the major areas of discussion over the past 18 months has been the Westar trust and the Westar Lectureship. In my previous report, I described how the Board had committed a portion of the income from the Westar funds to support the Discover the Universe Initiative. A big focus over the next 6 months will be working to re-establish the Westar Lectureship series. The Westar lectures occurred quite regularly in the 2000s but as far as I can tell was overtaken in 2009 by the International Year of Astronomy and never restarted. The CASCA Board is working with our EPO committee and Discover the Universe to implement a new model that combines a Westar lecture by an astronomer with hands-on teacher training activities offered by Discover the Universe. Expect to see a call for volunteers in early 2016.

Happy holidays!

Gemini News/Nouvelles de Gemini

By/par Stéphanie Côté
(Cassiopeia – Autumn/Automne 2015)

La version française suit

New Batch of Accepted Large and Long Programs in 2015

The results of the Large and Long Programs 2015 selection are out, and there are 5 new Programs that were accepted this year. All of them have US PIs, with a total of 8 Canadian Co-Is who are participating in three of the projects. Zachary Draper (PhD student at University of Victoria), Samantha Lawler (University of Victoria), Brenda Matthews (NRC Herzberg), Sebastian Bruzzone (PhD student at University of Western Ontario), Stan Metchev (University of Western Ontario), and Max Millar-Blanchaer (PhD student at University of Toronto) will be working on “Characterizing Dusty Debris in Exoplanetary Systems” led by Christine Chen (STScI). Chris Willott (NRC Herzberg) will be working with Yue Shen (Carnegie) on “A GNIRS Near-IR Spectroscopic Survey of z>5.7 Quasars”, and Craig Heinke (University of Alberta) will be working with Robert Hynes (Louisiana State University) on “Dynamical Masses of Black Holes and Neutron Stars from the Galactic Bulge Survey” using GMOS-S.

The two other accepted Large Programs for 2015 are led by Ian Crossfield (U of Arizona) “Validating K2’s Habitable and Rocky Planets with AO Imaging” and Catherine Huitson (University of Colorado) “The First Survey Dedicated to the Detection and Characterization of Clouds in Exoplanet Atmospheres”.

First GRACES Science Data Publically Available

A small set of science targets were observed with GRACES during its commissioning ahead of the 2015B semester. The targets were selected by the STAC and include a QSO, nuclei of nearby galaxies, a planetary nebula, some alpha-element rich stars, and a solar twin star, as well as spectrophotometric standards. The data both raw and reduced (via the Opera pipeline) are available publically here. The data are superb and GRACES throughput is even better than anticipated. Figure 1 shows a comparison with the performance of other high-resolution spectrographs on 8-10 meters telescopes and GRACES clearly outperforms them in the red starting at about 600 nm. GRACES was developed at NRC Herzberg in collaboration with FiberTech Optica (from Kitchener, ON), and the help of Gemini and CFHT staff. Another great success story for Canadian innovative technology!

Figure 1 - This shows the measured S/N obtained after a 1 hour observation of the star Feige 66 with GRACES (2 fiber mode, in black), compared to HIRES/Keck (in green) and UVES/VLT (in blue). In the red starting at about 600nm GRACES clearly outperforms them.

Figure 1 – This shows the measured S/N obtained after a 1 hour observation of the star Feige 66 with GRACES (2 fiber mode, in black), compared to HIRES/Keck (in green) and UVES/VLT (in blue). In the red starting at about 600nm GRACES clearly outperforms them.

Fast Turnaround Proposals: deadline every end of the month

This is a reminder that the Fast Turnaround Program is continuing on Gemini-North all through the year, and that there is a deadline for proposals at the end of every month. Accepted programs will be active a month later and for a total of 3 months. Already many Canadian programs have been accepted and observed. The next deadline is on September 30th (even though there is also a regular Call for Proposals for PI time). Note that GRACES is offered for this September FT call, as well as all other facility instruments in the North.

Users might be under the impression that the FT program should be used exclusively for observations that need to be carried out promptly. This is not at all the case. FT proposals can be aimed at following up unusual or unexpected astronomical events but also for pilot studies, or short self-contained projects, or speculative and risky short observations, or for the completion of a thesis when only a few short extra observations are needed or for the completion of an existing dataset to allow publication, or any other kind of short project.

The latest news is that the Board has just approved for FT proposals to be accepted for Gemini-South as well. The first call for proposals including Gemini South will probably be for the end of October deadline. The plan is that proposals for both telescopes will go into a single pool with time allocated according to merit rather than enforcing a strict 50:50 North:South division.

Please sign up to the Fast Turnaround mailing list by sending a message to gemini-FT-reminders+subscribe@gemini.edu (similarly, you can unsubscribe using gemini-FT-reminders+unsubscribe@gemini.edu). The mailing list will be used to send monthly deadline reminders and news about changes to the program that may affect or interest users.

Lots of Good Stuff in the Gemini Data Reductions User Forum

This Forum is a place for trading ideas, scripts and best practices, and taking part in discussions with other users of data reduction processes and strategies. If you have a general question about strategies or approaches to reduction of particular types of data, try the Forum to find help. And if you have written a script, procedure, or have tips for other users you are very welcome to share them on the Forum. Since its creation last year it is now getting populated with a lot of interesting information, for example you can find a GMOS IFU reduction cookbook and reduction scripts, a GMOS longslit reduction scripts including a Nod&Shuffle tutorial, a new NIFS Python data reduction pipeline, as well as scripts for GNIRS and Flamingos2 reductions. Check it out at DR Forum.

Note also that there is a short new tutorial on “Installing Ureka and PyRAF 101” written by Kathleen Labrie available here.

Recent Canadian Press Releases

  • The discovery of a young Jupiter-like exoplanet named 51 Eri b was announced by the GPI Campaign team. This is the first exoplanet discovered as part of the GPI Exoplanet Survey (GPIES), a survey of over 600 nearby stars to be carried out over the next three years. This new planet is about twice the mass of Jupiter and orbits a young star just 20 million years old. In addition to being what is likely the lowest-mass planet ever imaged, it is also the first one for which large amounts of methane have been directly detected in the atmosphere. This makes it very similar to the gas giant planets in our own Solar System, which have heavy methane dominated atmospheres. Thus 51 Eridani b gives us a glimpse of how Jupiter was when our solar system was young. GPIES is led by B.MacIntosh (Standford) and includes many Canadians: C.Marois, B.Matthews, L.Saddlemeyer (NRC Herzberg), Z.Draper, B.Gerard, M.Johnson-Groh (U of Victoria), J.Rameau, E.Artigau, R.Doyon, D.Lafreniere (U de Montréal), S.Bruzzone, S.Metchev (U of Western Ontario), J.Chilcote, J.Maire (Dunlap Institute), and M.Millar-Blanchaer (U of Toronto). You can view the full press release here.
    Figure 2 - GPI image of 51 Eri b. The bright central star has been mostly removed by a hardware and software mask to enable the detection of the exoplanet one million times fainter. Credits: J. Rameau (UdeM) and C. Marois (NRC Herzberg)

    Figure 2 – GPI image of 51 Eri b. The bright central star has been mostly removed by a hardware and software mask to enable the detection of the exoplanet one million times fainter. Credits: J. Rameau (UdeM) and C. Marois (NRC Herzberg)

  • A joint press release between University of Toronto and Gemini was released on September 16th 2015, presenting an updated orbit for beta Pic b based on new astrometric measurements taken in GPI’s spectroscopic mode spanning 14 months. The series of images captured between November 2013 to April 2015 shows the exoplanet β Pic b as it moves through 1 ½ years of its 22-year orbital period. Not only these are the most accurate measurements of the planet’s position ever made, but the data also enable to study the dynamical interactions of the exoplanet β Pic b and the surrounding debris disk. The orbital fit also constrains the stellar mass of Beta Pic, to 1.60\pm0.05 solar masses. The study was led by M.Millar-Blanchaer (U of Toronto), with the help of D-S.Moon (U of Toronto), J.Chilcote, J.Maire (Dunlap Institute), Z.Draper (U of Victoria), J.Dunn, C.Marois, L.Saddlemeyer (NRC Herzberg). To see the full press release and animation click here.


Nouveaux Programmes Longs et Larges accceptés pour 2015

Les résultats de la sélection des Longs et Larges programmes de 2015 sont sortis, et il y a 5 nouveaux programmes qui ont été acceptés cette année. Ils ont tous un PI américain, avec un total de 8 Canadian qui collaborent à trois des projets. Zachary Draper (étudiant PhD à l’Université de Victoria), Samantha Lawler (Université de Victoria), Brenda Matthews (NRC Herzberg), Sebastian Bruzzone (étudiant PhD à l’Université de Western Ontario), Stan Metchev (Université Western Ontario), et Max Millar-Blanchaer (étudiant PhD à l’Université de Toronto) travailleront sur ” Characterizing Dusty Debris in Exoplanetary Systems ” dirigé par Christine Chen (STScI). Chris Willott (NRC Herzberg) quant à lui travaillera avec Yue Shen (Carnegie) sur “A GNIRS Near-IR Spectroscopic Survey of z>5.7 Quasars “, et Craig Heinke (Université de l’Alberta) travaillera avec Robert Hynes (Louisiana State University) sur les « Dynamical Masses of Black Holes and Neutron Stars from the Galactic Bulge Survey” à l`aide de GMOS-S.

Les deux autres grands programmes acceptés pour 2015 sont dirigés par Ian Crossfield (U de l’Arizona) “Validating K2’s Habitable and Rocky Planets with AO Imaging” et Catherine Huitson (Université du Colorado) « The First Survey Dedicated to the Detection and Characterization of Clouds in Exoplanet Atmospheres “.

Premières Données Scientifiques de GRACES Maintenant Disponibles Publiquement

Quelques cibles scientifiques ont pu être observées avec GRACES lors de sa mise en service pour le semestre 2015B. Les cibles avaient été choisies par le STAC et comprennent un QSO, des noyaux de galaxies proches, une nébuleuse planétaire, certaines étoiles riches en alpha-éléments, et une étoile similaire au Soleil, ainsi que des étoiles standardes de spectrophotométrie. Les données à la fois brutes et réduites (via le pipeline Opera) sont disponibles publiquement ici. Les données sont superbes et le throughput de GRACES est encore mieux que prévu. La figure 1 montre une comparaison avec les performances des autres spectrographes à haute résolution sur des télescopes de 8-10 mètres, et GRACES les surpasse largement dans le rouge à partir d’environ 600 nm. GRACES a été développé au CNRC Herzberg en collaboration avec FiberTech Optica (de Kitchener, ON), et avec l’aide du personnel Gemini et TCFH. Encore une grande réussite pour la technologie innovatrice canadienne!

Figure 1 - Signal-sur-bruit mesuré après 1 heure d`observation de l'étoile Feige 66 avec GRACES (en mode 2-fibres, en noir), par rapport à HIRES / Keck (en vert) et UVES / VLT (en bleu). Dans le rouge à partir d`environ 600 nm GRACES  les surpasse largement.

Figure 1 – Signal-sur-bruit mesuré après 1 heure d`observation de l’étoile Feige 66 avec GRACES (en mode 2-fibres, en noir), par rapport à HIRES / Keck (en vert) et UVES / VLT (en bleu). Dans le rouge à partir d`environ 600 nm GRACES les surpasse largement.

Demandes `Fast Turnaround`: date limite toujours à la fin du mois

Ceci est un rappel que le programme `Fast Turnaround` se poursuit à Gemini-Nord tout au long de l’année, et que la date limite pour les demandes est à la fin de chaque mois. Les programmes acceptés seront actifs un mois plus tard et pour un total de 3 mois. Déjà de nombreux programmes canadiens ont été acceptés et observés. La prochaine date limite est le 30 Septembre (même s`il y a aussi un appel de demandes régulier). Notez que GRACES est offert pour cet appel Fast Turnaround de Septembre, ainsi que tous les autres instruments Gemini du Nord.

Les utilisateurs ont peut-être l’impression que le programme FT doit être utilisé exclusivement pour les observations qui doivent être effectuées rapidement. Cela n`est pas du tout le cas. Les demandes FT peuvent viser des événements astronomiques inhabituels ou inattendus, mais peuvent aussi être pour des études pilotes ou des projets autonomes courts, ou des observations courtes spéculatives et risquées, ou pour la finition d’une thèse où seules quelques observations supplémentaires courtes sont nécessaires, ou pour l`achèvement d’un ensemble de données existant pour en permettre la publication, ou pour tout autre type de projet court.

Aux dernières nouvelles le Conseil de direction vient d’approuver que le programme FT soit ouvert à Gemini-Sud aussi. Le premier appel de demandes qui comprendra Gemini-Sud sera probablement pour la fin d`Octobre. Le plan est que les demandes pour les deux télescopes iront dans un seul pool et le temps sera alloué selon le mérite plutôt que selon une application d’une stricte division 50:50 pour le Nord et le Sud.

S’il vous plaît veuillez vous inscrire à la liste de courriels pour le programme FT en envoyant un message à gemini-FT-reminders+subscribe@gemini.edu (de même, vous pouvez vous désinscrire en utilisant gemini-FT-reminders+unsubscribe@gemini.edu). Cette liste sera utilisée pour envoyer des rappels des dates limites mensuelles et des nouvelles sur des changements au programme qui pourraient intéresser les utilisateurs.

Beaucoup de Bonnes Choses dans le Forum de Réductions de Données Gemini

Ce forum est un lieu d’échanges d’idées, de scripts et des meilleures pratiques, et pour prendre part à des discussions avec d’autres utilisateurs sur les processus et stratégies de réduction de données. Si vous avez une question générale sur les stratégies pour la réduction de certains types de données, visitez le Forum pour trouver de l’aide. Et si vous avez écrit un script, une procédure ou avez des conseils pour les autres utilisateurs alors vous êtes les bienvenus pour les partager sur le Forum. Depuis sa création l’an dernier, il s`est maintenant peuplé de beaucoup d’informations intéressantes, par exemple vous pouvez trouver un cookbook de réductions pour GMOS-IFU et des scripts de réduction, des scripts de réduction pour GMOS en longue-fente qui comprend un tutoriel pour le mode Nod&Shuffle, un nouveau pipeline Python pour la réduction de données NIFS, ainsi que des scripts de réduction pour GNIRS et Flamingos2.
Visitez-le à: DR Forum.

Notez également qu’il y a un nouveau court tutoriel sur «Installation Ureka et PyRAF 101″ écrit par Kathleen Labrie ici.

Communiqués de Presse Canadiens Récents

  • La découverte d’une jeune exoplanète semblable à Jupiter nommé 51 Eri b a été annoncé par l’équipe de la campagne GPI. Ceci est la première exoplanète découverte dans le cadre du Sondage d`Exoplanètes GPI (GPIES), une étude de plus de 600 étoiles proches qui s`effectuera au cours des trois prochaines années. Cette nouvelle planète a environ deux fois la masse de Jupiter et tourne autour d’une jeune étoile de seulement 20 millions d’années. En plus d’être probablement la planète de plus faible masse jamais imagée, elle est également la première pour laquelle de grandes quantités de méthane ont été détectées directement dans son atmosphère. Cela la rend très semblable aux planètes géantes gazeuses de notre système solaire, qui ont des atmosphères lourdement dominées par le méthane. Ainsi 51 Eridani b nous donne un aperçu de ce que Jupiter avait l`air quand notre système solaire était jeune. GPIES est dirigé par B.MacIntosh (Standford) et comprend de nombreux Canadiens: C.Marois, B.Matthews, L.Saddlemeyer (Herzberg), Z.Draper, B.Gerard, M.Johnson-Groh (U de Victoria), J.Rameau, E.Artigau, R.Doyon, D.Lafreniere (U de Montréal), S.Bruzzone, S.Metchev (U of Western Ontario), J.Chilcote, J.Maire (Dunlap Institut), et M. Millar-Blanchaer (U de Toronto). Vous pouvez consulter le communiqué de presse au complet ici.
    Figure 2 - Image de GPI de 51 Eri b. L'étoile centrale lumineuse a été principalement éliminé par le coronagraphe ainsi que d`autres masques dans les logiciels pour permettre la détection de l'exoplanète un million de fois plus faible. Crédits: J. Rameau (UdeM) et C. Marois (CNRC Herzberg).

    Figure 2 – Image de GPI de 51 Eri b. L’étoile centrale lumineuse a été principalement éliminé par le coronagraphe ainsi que d`autres masques dans les logiciels pour permettre la détection de l’exoplanète un million de fois plus faible. Crédits: J. Rameau (UdeM) et C. Marois (CNRC Herzberg).

  • Un communiqué de presse conjoint de l’Université de Toronto et Gemini a été lançé le 16 Septembre 2015, présentant une mise à jour plus précise de l`orbite de l`exoplanète bêta Pic b basée sur de nouvelles mesures astrométriques prises dans le mode spectroscopique de GPI sur une échelle de temps de 14 mois. La série d’images captées entre Novembre 2013 et Avril 2015 montre l’exoplanète β Pic b se déplaçant sur 1 an et demi de sa période orbitale de 22 ans. Non seulement ce sont les mesures les plus précises jamais obtenues de la position de la planète, mais les données permettent également d’étudier les interactions dynamiques de l’exoplanète β Pic b et le disque de débris entourant l`étoile. Les nouvelles mesures de l`orbite permettent également de mieux contraindre la masse stellaire de Beta Pic, à 1,60 \ pm0.05 masses solaires. L’étude a été dirigée par M.Millar-Blanchaer (U de Toronto), avec l’aide de D-S.Moon (U de Toronto), J.Chilcote, J.Maire (Institut Dunlap), Z.Draper (U de Victoria), J.Dunn, C.Marois, L.Saddlemeyer (CNRC Herzberg). Pour voir le communiqué de presse et l’animation complète, cliquez ici.

Dissertation: The Evolution of Star Clusters in Tidal Fields

Jeremy_headshot

By Jeremy Webb
Thesis defended on July 17, 2015
Department of Physics & Astronomy, McMaster University
Thesis advisors: Alison Sills & Bill Harris (McMaster)

Abstract

Globular clusters are found in the halos of all types of galaxies, and have been shown to play major roles in the formation of stars and galaxies. The purpose of this thesis is to advance our level of understanding of the dynamical evolution of globular clusters through N-body simulations of clusters with a range of circular, eccentric, and inclined orbits. Theoretical studies have historically assumed that globular clusters experience a static tidal field, however the orbits of globular clusters are all non-circular and the tidal field of most galaxies is not symmetric. Understanding how clusters evolve in realistic potentials allows for them to be used to constrain the formation, merger history, and evolution of a host galaxy and even map out the current size, shape, and strength of a galaxy’s gravitational field.

We find that dense and compact clusters evolve as if they are in isolation, despite being subject to a non-static tidal field. For larger clusters, tidal shocks and heating inject energy into the cluster and significantly alter its evolution compared to previous studies. We describe how a non-static field alters the mass loss rate and relaxation time of a cluster, and propose methods for calculating a cluster’s size and orbit.

We then apply our work to clusters in the giant galaxies M87, NGC 1399, and NGC 5128. We consider each cluster population to be a collection of metal poor and metal rich clusters and generate models with a range of orbital distributions. From our models we constrain the orbital anisotropy profile of each galaxy, place constraints on their formation and merger histories, and explore the effects of nearby galaxies on cluster evolution.

By advancing studies of globular cluster evolution to include the effects of a non-static tidal field, we have made an important step towards accurately modelling globular clusters from birth to dissolution. Our work opens the door for globular clusters to be used as tools to study galaxy formation, evolution, and structure. Future studies will explore how galaxy formation and growth via the hierarchical merger of smaller galaxies will affect cluster evolution.

Dissertation: The Structure and Evolution of Unbound Star-Forming Molecular Clouds

RLWphoto

By Rachel Ward
Thesis defended on July 29, 2015
Department of Physics & Astronomy, McMaster University
Thesis advisors: Alison Sills & James Wadsley (McMaster)

Abstract

Recent generations of stars form principally, and possibly exclusively, in giant molecular clouds – large conglomerations of gas and dust primarily composed of molecular hydrogen and concentrated in the arms of spiral galaxies. These clouds are assumed to be gravitationally bound; however, recent observations suggest the presence of a substantial population of unbound clouds in the Milky Way. Using synthetic observations from high-resolution simulations of bound and unbound molecular clouds, we explore whether clouds in this mixed population could match observations of local molecular clouds. We find from the clouds in our sample that a state of virial equilibrium is not required to form stars and match the dynamics and structure of observed clouds, as described by the Larson scaling relations and the probability distribution function (PDF) of the mass surface density. As these clouds evolve, the underlying lognormal shape of the column density PDFs is effectively concealed as the peaks of their distributions shift to surface densities below observational detection thresholds, supporting recent observations which also find little to no evidence for a lognormal distribution in column density PDFs of nearby clouds. We explore these results further in an extragalactic context by simulating molecular clouds formed in a galactic disc, in order to demonstrate the role their environment, particularly the galactic shear, plays on their structure and evolution and on the star formation within them. We find that a substantial population of unbound molecular clouds forms naturally in a galactic disc environment and demonstrate that their presence not only matches galactic and extragalactic observations but also impacts several long-standing issues in star formation.

Dissertation: Molecular Gas Properties in Local Luminous Infrared Galaxies

kazimierzsliwa

By Kazimierz Sliwa
Thesis defended on July 27, 2015
Department of Physics & Astronomy, McMaster University
Thesis advisor: Christine Wilson (McMaster)

Abstract

In this thesis, I analyze the physical conditions such as temperature, volume density and column density of the molecular gas in four Luminous Infrared Galaxies (LIRGs): Arp 55, NGC 1614, VV 114 and NGC 2623. LIRGs are systems where two gas-rich galaxies are in the process of merging. The goal of my thesis is to look for trends in the molecular gas properties during the merger process. I use several observations of transitions of carbon monoxide (12CO) and its isotopologue 13CO from the Submillimeter Array, Combined Array for Research in Millimeter-wave Astronomy and Atacama Large Millimeter/submillimeter Array. The high-resolution observations allow me to analyze the molecular gas at several positions inside a single galaxy. The observations are fitted to models obtained from a radiative transfer code using a Bayesian likelihood method. I find that advanced mergers such as NGC 2623 and VV 114 have warmer (≥ 40 K), less dense (≤ 103 cm−3) molecular gas than early/intermediate stage mergers such as Arp 55 and NGC 1614. I suggest that there are mechanisms such as stellar winds, supernovae and AGN activity that dissipate the molecular gas and thus lower the density and warm the gas as the merger progresses. The molecular gas pressure of the advanced mergers is found to be lower by nearly an order of magnitude when compared to the early/intermediate stage mergers. I also find that the [12CO]/[13CO] abundance ratio in NGC 1614, VV 114 and NGC 2623 is unusually high (> 100) when compared to the interstellar medium value near the center of the Milky Way (∼ 30). Interestingly, Arp 55 does not conform to this trend with a [12CO]/[13CO] value of ∼ 30, similar to the Milky Way center. I suggest that nucleosynthesis may play a big role in enhancing the abundance ratio and/or the molecular gas from the outer radii of Arp 55 has not reached the central inner regions to drive the abundance ratio up. Nevertheless, Arp 55 is in an interesting merger stage. Finally, I measured the CO luminosity to molecular gas mass conversion factor, αCO, across the sample in search of the transition stage from a Galactic-like αCO to the 4-5 times lower value found in LIRGs. The four sources all have measured αCO values that are consistent with the LIRG value of 0.8 M⊙ (K km s−1 pc2)−1. I suggest that we look at an even earlier merger stage such as Arp 240 to find the point of transition. With the golden age of submillimeter astronomy upon us, this is just the beginning of furthering our knowledge of the merger process and what happens to the molecular gas, the fuel for all star formation.