Category Archives: News and Announcements

By / par Patrick Côté, John Hutchings (NRC Herzberg Astronomy & Astrophysics Research Centre)
(Cassiopeia – Spring / printemps 2022)

The CASTOR project continues to move forward as the Long Range Plan’s highest priority in space astronomy for the 2020s.

1. The ongoing CSA technical (STDP) study contract continues to make good progress. A recent review detailed the design and performance of the Fast Steering Mirror that will perform the fine guiding for the observatory. The recently launched James Webb Space Telescope utilizes the same guiding system, so there is significant heritage in this capability. Other work on the detectors and payload opto-mechanical issues continues.
2. The long-awaited Phase 0 study contract is underway as of March 8. This study overlaps the STDP work, and both studies will wrap up about one year from now. The prime deliverable from the Phase 0 study will be a fully characterized and thoroughly planned mission concept, with agreed partnerships, that can move immediately into the flight Phases A to E. It is hoped that partnership details and agreements with ISRO, JPL, and UK will be formulated during this time. The Phase 0 study consists of an industrial contract (led by Honeywell Aerospace) and a science team contract (led out of NRC/HAA), and now is formally a joint project between CSA and NRC. Science working groups (SWGs) and work contracts are in place with several Canadian universities.
3. The CASTOR and Indian INSIST teams continue to work on a common design and hold regular meetings. The partner teams also include JPL and UK, whose participation in the STDP and Phase 0 work are being formalized.
4. The ACURA board and the Coalition are fully informed and are carrying the message from Universities to the government to prepare for flight approval and funding. We welcome colleagues to join in SWG and outreach activities.

For more information on the mission, see the main page here.

By / par Erik Rosolowsky (U Alberta)
(Cassiopeia – Spring / printemps 2022)

After support from the US Decadal, the ngVLA project is beginning the next phase of its development: creating a fully costed design and a well developed science plan. Canada, along with Mexico and Japan, remains highly engaged as an international partner in the ngVLA planning process. Currently, the project is recruiting new members to the Science Working Groups and developing the next steps for what the next decade of National Radio Astronomy (NRAO) facilities looks like.

VLA/VLBA to ngVLA Transition Advisory Group

The NRAO has begun the process of developing a plan to transition from the operation of the Very Large Array (VLA) and Very Long Baseline Array (VLBA) to the ngVLA (see news article here). This activity will be led by the community-based “VLA/VLBA to ngVLA Transition Advisory Group”. Guided by the scientific opportunities planned for the coming decade, the Group will be charged to develop, quantitatively assess, and evaluate a finite number of possible VLA/VLBA to ngVLA transition options that can be prioritized on their scientific promise, cost and technical/personnel impacts. Nominations for the panel recently closed and the Group’s summary report is anticipated to be completed in early 2023.

Computational Astrophysics in the ngVLA Era: Synergistic Simulations, Theory, and Observations

This conference will be held 7-9 June 2022 at the Simons Foundation’s Flatiron Institute in Manhattan, New York, USA. The in-person conference will bring together theoreticians, modellers, and observers to discuss the computational astrophysics and observational challenges for the next generation of observatories, focusing on the ngVLA. The participation of early career scientists is particularly encouraged. Abstracts for oral presentations are due 1 April 2022.

By / par Patrick Hall (MSE Management Group Member)
(Cassiopeia – Spring / printemps 2022)

MSE and Astro2020

MSE and wide-field optical spectroscopy faired well in last year’s Astro2020 report (“Pathways to Discovery in Astronomy and Astrophysics for the 2020s”, U. S. National Academies of Sciences, Engineering, and Medicine 2021). The report reads, in part:

“Recommendation: The National Science Foundation (NSF) Division of Astronomical Sciences (AST) should create three tracks within the AST Mid-Scale Innovations Program … The strategic priorities track is an essential addition to the existing mid-scale program structure to ensure that it is responsive to decadal and community strategic priorities. The survey has identified one top priority for this element, a time-domain astrophysics program, and two co-equal areas – highly multiplexed spectroscopy and radio instrumentation. … There is very strong support for massively multiplexed spectroscopy across many sectors of the science community. … A dedicated facility would of course provide advantages over relying solely on existing infrastructure. Most glaring is the lack of high spectral resolution (R~20,000) multi-object spectrographs. … MSE and SpecTel presented plans to the panel for such a mode. … In all cases, the United States could envision playing a significant role in these projects through a MSRI-2-level investment, which could provide up to about 20 percent of the cost of a project like MSE, SpecTel, or up to about 50 percent of MegaMapper, perhaps split with DOE.”

From the MSE collaboration’s official statement, available here:

“The 2010 decadal plan highlighted the need for large telescopes and deep imaging surveys to explore the universe,” said Jennifer Marshall, MSE Project Scientist and associate professor at Texas A&M University. “We have built the MSE science case over the past decade with the understanding that multi-object spectroscopy is the natural follow-up to those large projects.”

Strengths encompass two of three of Astro2020’s priorities for mid-sized projects: time domain astronomy and highly multiplexed optical spectroscopy. The MSE detailed science case outlines the compelling science that MSE will execute, much of which falls within the three main science themes identified by Astro2020: “Worlds and Suns in Context” (exoplanets), “New Messengers and New Physics” (transient astrophysics), and “Cosmic Ecosystems” (the evolution of galaxies).

Regarding the State of the Profession, one of the committee’s recommendations is that “the astronomy community should work with representatives from local communities to define a Community Astronomy model of engagement that advances scientific research while respecting, empowering and benefiting the local community.” The MSE collaboration welcomes this recommendation, along with the other recommendations regarding diversity, equity and inclusion, broadening the academic pipeline, and working with our indigenous and local communities here in Hawai’i.

The CFHT board is “committed to the Maunakea Spectroscopic Explorer as the future of the facility. The Board is confident that, following deeply rooted CFHT practices, the MSE project will be respectful of our privilege to share the cosmos from Maunakea, and will continue CFHT’s long-standing history of engaging the Hawai’i Island community.”

MSE Pathfinder

MSE/CFHT plan to propose to NSF to develop an end-to-end Pathfinder: a multi object spectrograph fed at prime focus from the Canada France Hawaii Telescope. It will utilize the MSE spectrograph design and a scaled down fiber positioner (approximately 800 fibers) using the same technology as the fiber positioner for MSE.

The goal of the Pathfinder will be to retire many of the high-level technical risks for MSE by demonstrating on-sky the ability of the major hardware and software components of MSE, with the end result of an initial science product being produced and shared with the community. Construction of either the optical or the near-IR arms of the MSE spectrographs would achieve these goals. It is envisioned that the proposal to NSF will be led by MSE/CFHT, with co-investigators from US universities and NOIRLab.

The Pathfinder fibers will subtend one arcsecond on the sky but because of CFHT’s smaller aperture will be one-third the physical diameter of the fibers for MSE. Thus, the spectrographs offer the possibility of spectral resolution two or even three times that delivered for MSE (10,000 or potentially 15,000 instead of 5,000). A rough estimate of sensitivity is that the Pathfinder will reach AB=22 at wavelengths longer than 400 nm at SNR=2 per resolution element in one hour.

MSE/CFHT are actively seeking input on science projects for both the optical and near-IR Pathfinder options. Key projects are envisioned to be galactic archeology, stellar spectroscopy for abundances and stellar evolution studies, and time-domain astrophysics (specifically, follow-up of transients to demonstrate the dynamic scheduling capabilities that will be possible with MSE).

If you are interested in the MSE Pathfinder, you can receive updates by joining the MSE Science Team at mseinfo@mse.cfht.hawaii.edu.

MSE/WFMOS and CFI

In parallel to the pathfinder efforts, Canadian proponents of WFMOS (Wide-Field Multi-Object Spectroscopy) are submitting a CFI proposal to obtain funding for a targeted set of conceptual and preliminary design needs widely applicable to all potential 10-meter-class WFMOS facilities, including but not limited to MSE. CFI envelope funding have been allocated at York, Waterloo, UBC, Toronto, Saint Mary’s, Western and Manitoba.

The proposal encompasses work on WFMOS facility enclosures, on software needed for end-to-end survey design & implementation, near-real-time survey optimization, and data reduction & analysis, and on the fiber-optic multiplexing systems and spectrographs required to meet the stringent scientific requirements of these facilities. Questions regarding the proposal can be directed to Pat Hall.

MSE Project Scientist

Prof. Jennifer Marshall plans to step down as Project Scientist later this year. She states, “I have thoroughly enjoyed working with all of you for the past three years, and going forward I fully intend to stay very engaged with the project and with all of you.”

The MSE Project office is now seeking nominations for a new Project Scientist. The detailed job description can be found here.

While the position is unpaid, there are financial and other benefits that come with the position, including the potential for MSE to provide funding for travel, summer salary support, and teaching buyout. Partial-time candidates will be fully considered. The position is open to mid-career and senior scientists. “The next Project Scientist will have the benefit of getting to work with the very excellent leadership team in the Project Office, which has been a pleasure for me. I have thoroughly enjoyed serving in this position and I’m sure my successor will also–as you all know, MSE is a great project!”

Your MSE Representatives for Canada

MSE Science Advisory Group Members: Ting Li (U Toronto) and Kim Venn (U Victoria)

MSE Management Group Members: Laura Ferrarese (HAA) and Patrick Hall (York U)

Canada is also represented among the MSE Science Team Working Group Leads by Prof. Ting Li (U. Toronto, Astrophysical Tests of Dark Matter WG co-Lead) and Prof. Will Percival (U. Waterloo, Cosmology WG co-Lead).

By / par Bryan Gaensler (U. Toronto, CIRADA Director)
(Cassiopeia – Spring / printemps 2022)

The Canadian Initiative for Radio Astronomy Data Analysis (CIRADA), a pilot project for Canada’s planned Square Kilometre Array Regional Centre, is producing science-ready public data products for large surveys being conducted with three telescopes: the Very Large Array (VLA), the Australian Square Kilometre Array Pathfinder (ASKAP), and the Canadian Hydrogen Intensity Mapping Experiment (CHIME). These products (e.g., images, cubes, time series spectra, catalogues, databases, alerts, pipeline algorithms, and software tools) utilise Canadian Advanced Network for Astronomical Research (CANFAR) services and will be searchable and usable by professional astronomers and the general public, through the Canadian Astronomy Data Centre (CADC). Users of our science-ready data products will be able to leverage for viewing images data and tabular catalogues directly through our portal. Currently our services include:

1. A “Quicklook Catalogue” of 1.7 million radio sources from the first epoch of the VLA Sky Survey (VLASS) including a second version that contains data on sidelobe probabilities, as well as the software pipelines that were used to generate the catalogues along with detailed user manuals. Next steps: Our team is currently in the process of producing an updated version of the catalogue using updated first epoch images that have had astrometry corrections made as well as a first catalogue using images from the second epoch. Both catalogues will be available in Q2 2022. We are also planning to co-release a VLASS Single Epoch catalogue when the first 1000 square degrees become available in Q3 2022.
2. pyink, developed in collaboration with Dr. Tim Galvin, a tool that simplifies the preprocessing and analysis that is required to train a self-organising map (SOM) using PINK. pyink can be used (i) to produce catalogues of double and multiple radio sources, (ii) to classify radio sources as either complex or simple sources, (iii) to find source orientations, and (iv) as an annotation tool. Next steps: Our team has recently hired a new developer to explore opportunities to use this tool to expand the identification of complex sources.
3. An Image Cutout Provider that allows astronomers to quickly visualise data from multiple surveys (VLASS Quicklook, GLEAM, FIRST, NVSS, WISE, PanSTARRS, SDSS I-II) at a given position in the sky and to download the data for further analysis. (PLEASE NOTE THAT THE ASTROMETRIC ERRORS THAT WERE PREVIOUSLY REPORTED ARE NOW RESOLVED.) Next steps: We are in the process of extending the application of our cutout provider for use with RACS, VLASS Single Epoch, and VCSS.
4. The RM-Tools software package for radio polarimetry analysis, including 1D and 3D RM synthesis, RM-clean and QU fitting on polarised radio spectra. Next steps: Our team is currently adding complementary tools and working on an RM Standards package which will be released in the coming months. We are collaborating with POSSUM scientists, CADC and the Australian Square Kilometre Array Regional Centre on a pipeline to mosaic, re-tile, re-grid and perform ionospheric corrections on POSSUM cubes that can be used to generate Faraday depth cubes and other science-ready data products using the RM synthesis tools.
5. Hydra: a source finder comparison and analysis tool that can be used to compare multiple source-finding algorithms on radio continuum data along with examples and detailed instructions.
6. A mock-cube generator suite that can be used to generate realistic data cubes for a single galaxy model, or a suite of galaxy models generated from standard scaling relations. Next steps: Our team is coordinating efforts with the WALLABY survey to co-release pilot observations of the Hydra, Norma, and NGC 4636 fields and rotating disk models which will be accessible for download or for use with CADC TAP services through our portal
7. An alpha-version of the VLASS Transient Marshal is currently being readied for testing, with a full release planned before the end of the year.

Access to all of CIRADA’s services, software tools and data products is available at cirada.ca.

(Cassiopeia – Spring / printemps 2022)

by / par Dr. Keegan C. Marr
Thesis defended on February 11, 2022
Department of Physics and Astronomy, University of Western Ontario
Thesis advisor: Prof. Carol E. Jones

Abstract
This thesis focuses on the evolution of the disks of two classical B-emission (Be) stars, 66 Ophiuchi and Pleione, and on the thermal structure for disks tilted out of the star’s equatorial plane.

We used a hydrodynamic code to model the disk of the Be star 66 Ophiuchi. Observations from 1957 to 2020 were compiled to follow the growth and subsequent dissipation of the disk. Our models are constrained by new and archival photometry, spectroscopy and polarization observations. Using Markov chain Monte Carlo methods, we confirm that 66 Oph is a B2Ve star. We constrain the density profile of the disk before dissipation using a grid of disk models. At the onset of dissipation, the disk has an equatorial density of ρ(R) = 2.5 × 10^-11 (R/R_∗)^-2.6 g cm^-3. After 21 years of disk dissipation, our work shows that 66 Oph’s outer disk remains bright in the radio. We find an isothermal disk with constant viscosity with an α = 0.4 and an outer disk radius of ~115 stellar radii, best reproduces the dissipation. We determined the interstellar polarization in the direction of the star in the V-band is p = 0.63 +/- 0.02% with a polarization position angle of θ_IS ~ 85.7 +/- 0.7°. Using the Stokes QU diagram, we find the intrinsic polarization position angle of 66 Oph’s disk is θ_int ~ 98 +/- 3°.

We acquired H_α spectroscopy from 2005 to 2019 that shows Pleione has transitioned from a Be phase to a Be-shell phase. We created disk models which successfully reproduce the transition from Be to Be-shell with a disk model that varies in inclination while maintaining a constant, equatorial density of ρ(R) = 3 × 10^-11 (R/R_∗)^-2.7 g cm^-3, and an H_α emitting region extending to R_out = 15R_eq. We use a precessing disk model to follow variability in disk inclination over 120 years. The best-fit disk model precesses with an inclination between ∼25^° and ∼144^° with a period of ∼80.5 years. Our precessing models match some of the observed variability but fail to reproduce all of the historical data available. Therefore, we propose an ad-hoc model based on our precessing model and recent disk tearing simulations of similar systems. In this model, a single disk is slowly tilted to an angle of 30^° from the stellar equator over 34 years. Then, the disk is torn by the companion’s tidal torque, with the outer region separating from the innermost disk. The inner disk returns to the stellar equator as mass injection remains constant. The outer disk precesses for ∼15 years before gradually dissipating. This model reproduces all the variability trends, repeating every 34 years.

Our research on Pleione led to a detailed investigation of the thermal structure of tilted disks. For this research, we modelled the radiative transfer in tilted disks self-consistently. We constructed disk models for a range of spectral types, rotation rates and disk densities. We find as the tilt angle increases to 60, the minimum disk temperature of our B0 V star model, with W = 0.95 and ρ₀ = 10^-11 g cm^-3, can increase up to ∼114%, while the maximum disk temperature decreases by up to ∼8%. When W = 0.7, the changes in disk temperature for the same model are smaller, and at lower density the disk temperature increases globally. In the B2 V model, both the disk temperature and ionization fraction globally increase. In the B5 V and B8 V models, the disk temperature globally decreases, but increases around ∼10R_eq. The ionization fraction increases as modest changes to the disk temperature allow it to exceed the hydrogen ionization temperature. Overall, we find that the trends in the disk temperature and ionization fraction with the disk tilt angle greatly depend upon the stellar spectral type.

By / par Gerald Schieven (ALMA)
(Cassiopeia – Spring / printemps 2022)

Cycle 9 Call for Proposals

On March 24, the Joint ALMA Observatory will issue its call for proposals (CfP) for the Cycle 9 period of 1 October 2022 through 30 September 2023. The deadline for proposals will be 21 April, 2022 at 15UT. Proposals are to be submitted using the Cycle 9 Observing Tool (OT), available through the ALMA Science Portal. A full list of science capabilities and other information can also be found on the Science Portal.

Proposals are being solicited for the 12-m Array in all configurations (with maximum baselines from 0.16 km to 16.2 km), and for the ACA (including the 7-m and TP Array). Note that there will NOT be a supplemental call for stand-alone ACA proposals (i.e. those requiring just the 7-m and TP Arrays) during Cycle 9. All such proposals should be submitted during the normal call with deadline 21 April.

Once again, proposals will be submitted using the dual-anonymous procedure, which requires that PIs write their proposals in a way that preserves anonymity. In addition, all proposals requesting less than 50 hours on the 12-m Array, or 150 hours on the ACA in stand-alone mode, will be reviewed through the distributed peer review system.

Some the new capabilities being offered in Cycle 9 include:

• High-frequency and long-baseline observations, including Band 8 in configurations up through C-10, Band 9 in configurations up through C-9, and Band 10 in configurations up through C-8. For the first time, observations can be requested for angular resolutions as small as 9 milliarcseconds at 600µm (500 GHz).
• Solar Total Power regional mapping scans in bands 3, 5, 6, and 7
• VLBI continuum observations in Band 7
• VLBI spectral line observations in Band 3

Webinars for Novice Users (and those wishing a refresher)

A series of webinars will be held in late March and early April on ALMA basics and capabilities, and on proposal preparation and review. Registration is free.

These webinars are being organized by the ALMA Ambassadors, a program that provides some funding to young researchers, in exchange for organizing an ALMA workshop in your home area. This program is open to grad students and post-docs in any university or research institute in North America. Stay tuned to the CASCA exploder to be notified of the next deadline to apply for this program.

In addition to the webinars, Observing with ALMA – A Primer provides a basic introduction to radio interferometry, ALMA, its capabilities, and examples of science projects that could be observed with ALMA. The goal of the document is that, with all the basic information in one place, and a few examples of how to plan a science observation, this document can help all astronomers become familiar with ALMA’s capabilities and to start planning their own ALMA observations.

By / par Gregg Wade (on behalf of the Canadian BRITE Team)
(Cassiopeia – Spring / printemps 2022)

BRITE-Constellation is an international space astronomy mission consisting of a fleet of 20x20x20 cm nanosatellites dedicated to precision optical photometry of bright stars in two photometric colours. The mission continues in full science operations, with 38 datasets available in the public domain from the BRITE public archive. As of April of 2020, all data is made public as soon as decorrelation is complete, with no proprietary period.

The BRITE mission is a collaboration between Canadian, Austrian and Polish astronomers and space scientists. The Canadian partners represent University of Toronto, Université de Montréal, Mount Allison University, and Royal Military College of Canada. The mission was built, and the Canadian satellites operated by, the University of Toronto Institute for Aerospace Studies Space Flight Lab (UTIAS-SFL). The Canadian Space Agency funded the construction of the Canadian satellites, and continues to support their day-to-day operations.

Operations

There are five BRITE satellites in the Constellation, which work together to obtain well-sampled, long term continuous (~6 months) light curves in both red and blue band passes across a variety of sky fields.

As this issue of Cassiopeia went to press, the assignments of the BRITE nanosats were:

• BRITE Toronto (Canada): This satellite observes with a red filter. It is currently observing the Vel-Pup VIII field. (As indicated by the roman numeral, Vel-Pup is a BRITE legacy field being observed for the 8th time.
• BRITE Lem (Poland): Lem observes with a blue filter, but is currently idle due to unresolved stability issues.
• BRITE Heweliusz (Poland): Heweliusz observes with a red filter. It has recently finished observing the Orion VIII field and is being set up on the Cru-Car IV field.
• BRITE Austria (Austria): BRITE Austria observes with a blue filter. It has recently completed observing the Orion VIII field.
• UniBRITE (Austria): Currently out of order.

The BRITE Constellation observing program is currently set through mid-2022. Details of the observing plan will be available on the BRITE photometry Wiki page.

Recent Science Results

“A study of stochastic photometric variability in the winds of Galactic Wolf-Rayet stars” (Lenoir-Craig et al., ApJ 925, 79)

In order to explore how the ubiquitous short-term stochastic variability in the photometric observations of Wolf-Rayet (WR) stars is related to various stellar characteristics, we examined a sample of 50 Galactic WR stars using 122 lightcurves obtained by the BRIght Target Explorer-Constellation, Transiting Exoplanet Survey Satellite and Microvariability and Oscillations of Stars satellites. We found that the periodograms resulting from a discrete Fourier transform of all our detrended lightcurves are characterized by a forest of random peaks showing an increase in power starting from ~0.5 day^-1 down to ~0.1 day^-1. After fitting the periodograms with a semi-Lorentzian function representing a combination of white and red noise, we investigated possible correlations between the fitted parameters and various stellar and wind characteristics. Seven correlations were observed, the strongest and only significant one being between the amplitude of variability, α₀, observed for hydrogen-free WR stars, while WNh stars exhibit correlations between α₀ and the stellar temperature, T_∗, and also between the characteristic frequency of the variations, ν_char, and both T_∗ and v_∞. We report that stars observed more than once show significantly different variability parameters, indicating an epoch-dependent measurement. We also find that the observed characteristic frequencies for the variations generally lie between -0.5 < log n < 0.5, and that the values of the steepness of the amplitude spectrum are typically found in the range -0.1 < log g < 0.5. We discuss various physical processes that can lead to this correlation.

BRITE orbital-mean magnitudes of WR24 from the 36-Car-II field as a function of the Heliocentric Julian Date, after subtraction of the median, showing the stochastic photometric variability of this star.

Conferences, Resources, and Social Media

Conferences

The BRITE team does not plan to host any conferences at this time.

Resources

The BRITE Public Data Archive, based in Warsaw, Poland, at the Nikolaus Copernicus Astronomical Centre, can be accessed here.

The mission Wiki (including information on past, current and future fields) can be accessed here.

BRITE Constellation is on Facebook, at @briteconstellation

The BRITE International Advisory Science Team

The BRITE International Advisory Science Team (BIAST), which consists of BRITE scientific PIs, technical authorities, amateur astronomers, and mission fans, advises the mission executive on scientific and outreach aspects of the mission. If you’re interested in joining BIAST, contact Dr. Catherine Lovekin, the chair of BEST.