President’s Report

By / par Rob Thacker (CASCA President)
(Cassiopeia – Winter / hivers 2019)

Dear CASCA Members, 

This fall has been a busy few months! I hope you have had a chance to recover from the efforts of proposal writing on top of detailed LRP consultations.

Since I last communicated, we have a welcomed the new CASCA Administrator, Jessica Marsano, and I’d like to encourage you to both welcome Jessica and say a big thank you to Susan Di Francesco who officially steps down on December 31st. On the administrative side we have finally solved the headache that PayPal was presenting, and I’m glad to say as of late November we are again able to accept payments via that route. I encourage anyone to take a read of a Kafka novel and then to send an email to PayPal, as that seems appropriate preparation for dealing with them.

The awarding of this year’s Nobel Prize for Physics for work in astronomy was especially exciting, albeit with the caveats of the known issues with the Nobel awards. After much discussion within the CASCA Board we have the following to say:

The CASCA Board was delighted to see that astronomy and cosmology were the focus of this year’s Nobel Prize for Physics. The work of Jim Peebles (who was born in Manitoba) played a foundational role in many areas of cosmological physics (including the large-scale structure of galaxies and the cosmic microwave background radiation). The other laureates also richly deserve their prizes: the discovery of 51 Pegasi b by Michel Mayor and Didier Queloz opened up the field of exoplanet observations and helped turn it into the spectacularly vibrant area of astrophysics that it is today. We wholeheartedly congratulate Drs Peebles, Mayor and Queloz for their exceptional accomplishments.

Following the awarding of the prize, there has been a number of questions about which particular exoplanet should be acknowledged as the most key discovery. The existence of pulsar planets (e.g.
Wolszczan & Frail, Nature, 355, 145, 1992) and particularly large gas giants/brown dwarfs (Latham et al., Nature, 339, 38, 1989) were known prior to the 51 Pegasi announcement.

In the midst of this, the CASCA Board thought it appropriate to remind members of the work of Bruce
Campbell, Gordon Walker, and Stephenson Yang (ApJ, 331, 902, 1988) which also played an important
role in founding the field of exoplanet research. In particular, we would like to highlight their work on gamma Cephei b. Their long-term monitoring program on the CFHT from 1981 to 1993 had sufficient sensitivity to discover Jupiter-like planets, and with modern statistical methods the 1995 follow-up work of Walker et al. (Icarus, 116, 359, 1995), which included a new analysis of gamma Cephei b data, would be considered a strong detection. The estimated period of 2.52 yrs in that work is very close to the now accepted value of 2.47 yrs.

However, following the 1992 analysis which speculated that the gamma Cephei b signal was close to a
possible pulsation mode, the 1995 work was treated with some skepticism. There is no argument that
the work of Drs Mayor & Queloz, as well as their collaborators, created an unexpected and important avenue of exoplanet research, and while celebrating Mayor and Queloz, we think it appropriate to also celebrate the pioneering work of Campbell, Walker and Yang.

CASCA “Seeds” Program

I’d like to highlight the CASCA “Seeds” program that was announced at the AGM this summer: each year, the CASCA Board will allocate up to $5K of seed funding to activities spearheaded by CASCA
members that benefit the Society. All initiatives and/or events that are consistent with CASCA’s Mission Statement are eligible to receive CASCA Seed funding, though an emphasis will be placed on activities that are difficult to fund via other mechanisms. The intent of the CASCA Seeds program is to support new and/or unique opportunities for CASCA members; the same initiative is therefore unlikely to be funded more than once. 

Full details of the program and application process are available here (English) and here (Francais). We hope that some great new initiatives can grow out of this program!

Sustainability

Anyone who has read through the tremendous list of white papers submitted to the LRP process cannot
have failed to have noticed a very significant number of recommendations put squarely in the hands of CASCA as an organization. On one hand I feel buoyed by the great faith in CASCA that you are showing by making these recommendations, although on the other hand I confess that the entire suite comes across as somewhat daunting. The Board is currently working on determining what to do about these many recommendations, especially given that these recommendations are input into the LRP process, and we need to let that process take its course.

Many very important issues have been brought up, especially around ethical considerations for our field, but one concern stood out for immediate action in the view of several Board members, specifically that of sustainability. I am thus happy to notify the community that the Board has struck an ad hoc committee on sustainability and we are in the process of filling that committee as I write. We have agreed to run this committee in an ad hoc form for one year, with a view to reviewing its progress at the end of 2020.

I’d like to end by again thanking all of you – again – for your efforts in supporting CASCA and the
astronomy community. With a couple of exceptions for our staff members, we are a Society of volunteers and depend entirely on your efforts to make our activities possible.

Happy Holidays, and all the best for 2020!

Rob

Image release: Giant Magnetic Ropes in a Galaxy’s Halo

Galaxy Halo

Credit: Composite image by Jayanne English of the University of Manitoba, with NRAO VLA radio data from Silvia Carolina Mora-Partiarroyo and Marita Krause of the Max-Planck Institute for Radioastronomy. The observations are part of the project Continuum HAlos in Nearby Galaxies — an EVLA Survey (CHANG-ES). The optical data were from the Mayall 4-meter telescope, collected by Maria Patterson and Rene Walterbos of New Mexico State University. Arpad Miskolczi of the University of Bochum provided the software code for tracing the magnetic field lines.

This image of the “Whale Galaxy” (NGC 4631), made with the National Science Foundation’s Karl G. Jansky Very Large Array (VLA), reveals hair-like filaments of the galaxy’s magnetic field protruding above and below the galaxy’s disk.

The spiral galaxy is seen edge-on, with its disk of stars shown in pink. The filaments, shown in green and blue, extend beyond the disk into the galaxy’s extended halo. Green indicates filaments with their magnetic field pointing roughly toward us and blue with the field pointing away. This phenomenon, with the field alternating in direction, has never before been seen in the halo of a galaxy.

“This is the first time that we have clearly detected what astronomers call large-scale, coherent, magnetic fields far in the halo of a spiral galaxy, with the field lines aligned in the same direction over distances of a thousand light-years. We even see a regular pattern of this organized field changing direction,” said Marita Krause, of the Max-Planck Institute for Radioastronomy in Bonn, Germany.

An international team of astronomers who are part of a project called the Continuum HAlos in Nearby Galaxies — an EVLA Survey (CHANG-ES), led by Judith Irwin of Queen’s University in Ontario, said the image indicates a large-scale, coherent magnetic field that is generated by dynamo action within the galaxy and spirals far outward in the form of giant magnetic ropes perpendicular to the disk.

“We are a little bit like the blind men and the elephant, since each time we look at the galaxy in a different way we reach a different conclusion about its nature! However, we seem to have one of those rare occasions where a classical theory, about magnetic generators called dynamos, predicted the observations of NGC 4631 quite well. Our dynamo model produces spiralling magnetic fields in the halo that are a continuation of the normal spiral arms in the galaxy’s disc,” said Richard Henriksen, of Queen’s University.

The scientists are continuing their work to further refine their understanding of the galaxy’s full magnetic structure.

The image was made by combining data from multiple observations with the VLA’s giant dish antennas arranged in different configurations to show both large structures and finer details within the galaxy. The naturally-emitted radio waves from the galaxy were analyzed to reveal the magnetic fields, including their directions.

The scientists said the techniques used to determine the direction of the magnetic field lines, illustrated by this image, now can be used on this and other galaxies to answer important questions about whether coherent magnetic fields are common in galactic halos and what their shapes are.

Building such a picture, they said, can answer important questions such as how galaxies acquire magnetic fields, and whether all such fields are produced by a dynamo effect. Can these galaxy halo fields illuminate the mysterious origin of the even larger intergalactic magnetic fields that have been observed?

NGC 4631, 25 million light-years from Earth in the constellation Canes Venatici, is about 80,000 light-years across, slightly smaller than our own Milky Way. It was discovered by the famous British astronomer Sir William Herschel in 1787. This image also shows a companion, NGC 4627, a small elliptical galaxy, just above NGC 4631.

https://public.nrao.edu/news/giant-magnetic-ropes/
The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

The results were reported in the journal Astronomy & Astrophysics. https://arxiv.org/abs/1910.07590

The theoretical models are described in Woodfinden et al. 2019 MNRAS, 487, 1498.