Active B Star Commission Proposal

Supporting Material

This page summarizes the supporting material for the Commission Proposal, submitted to the IAU, proposing to elevate the current Working Group on Active B stars to Commission status. The Letter of intent, as well as the content of this page, will evolve into the final application, considering the input given by the IAU governing bodies, the WG members, and interested parties in general. For the background of this process have a look at the IAU announcement of the Commission reform and the proposal guidelines.Content

  1. Structure of the Proposed Commission
  2. Current Activities and Services to the Community
  3. Observational Advances Relevant to the Field of Active B Stars
  4. Theoretical and Computational Advances
  5. Relation to Commissions and Working Groups
  6. Relation to Amateur Astronomers

Structure of the Proposed Commission

Structure of the Organizing Committee

The WGABS has a long history of democratic involvement of its members, and thanks to this process also a history of well balanced OCs in terms of gender, geographic distribution, and career stage. The eight voting members of the WGABS OC are elected for two triennia. Each triennium four of the terms expire and need to be re-elected. The chairperson is then elected among the OC in the beginning of each triennium, where it is standing practice to chose a member in the second triennium for chairperson to ensure continuity. In addition to these voting members, three further members are non-voting members ex officium. These are the president of Division G, the previous chairperson, and the editor-in-chief of the WG's publication, the Be Star Newsletter.

Given the positive experiences with the above structure, a Commission on Active B Stars would wish to follow this example closely. In particular, the Commission proposers, who are all members of the current WGABS OC who would remain in the OC, would step down after the first triennium to start the alternating election process. In addition to a president and vice-president, the OC would elect a secretary among its members to organize contact with and feedback from the membership.

Membership of the WG and Potential Commission Membership

The WGABS currently has over 190 members, as defined by the subscribers to our mailing list. The WGABS welcomes non-IAU members, but the WG by-laws restrict the electorate to those who are IAU members. Since for a Commission already the membership is restricted to IAU members, an Active B Star Commission could be expected to have about 130 members in the beginning (the current WG electorate), with a growing interest as the Commission would expand, compared to the current WG, its main field and activities. Judging from activities like conference attendance and publications in the field, we expect the number of potentially interested IAU members to be larger than the number of current WGABS IAU members.

The 60 WGABS members who are not IAU members would remain to be Newsletter/mailing list subscribers, but be given limited user rights on the WGABS website, while IAU members would be given more extensive access, in particular to parts of the site concerning elections and other administrative issues.

Current Activities and Services to the Community

The working group activities, listed below, serve as a baseline on which the Commission would build and expand its activities.


Since 1976 the WGABS and its predecessor have hosted six IAU-sponsored meetings.

  • IAU Symposium 70, Be and Shell Stars (Bass River, Cape Cod, MA, 15-18 September 1975, predated WG)
  • IAU Symposium 98, Be Stars (Munich, Germany, 6-10 April 1981)
  • IAU Colloquium 92, Physics of Be Stars (Boulder, CO, 18-22 August 1986)
  • IAU Symposium 162, Pulsation, Rotation and Mass Loss in Early-Type Stars (Antibes, Juan-les-Pins, France, 5-8 October 1993)
  • IAU Colloquium 175, The Be Phenomenon in Early-Type Stars (Alicante, Spain, 28 June-2 July, 1999)
  • IAU Symposium 272, Active OB Stars: Structure, Evolution, Mass-Loss, and Critical Limits (Paris, France, 19-23 July 2010)

The WGABS has also endorsed many other IAU meetings, and has submitted a proposal for an IAU symposium in February 2016 to be held in Brazil. Several smaller meetings and workshops (for instance, a meeting in London/Ontario in Canada, 2014, and an ESO workshop in Foz do Iguacu in Brazil, 2012, just to name two recent ones) have been coordinated by the WGABS as well.

Be Star Newsletter and WG website

The Be Star Newsletter, published since 1980, has served as a continuous focal point of the community. The full archive of all issues is available in pdf format. The BeSN has evolved in several steps, and in the future will be no longer strictly page & volume based as it was in issues 1 to 40. Instead, contributions from each triennium will be archived together electronically to form a closed "volume", starting with Vol. 41 for the current triennium, and the next volume then start to accumulate contributions over the next triennium. A part of these contributions is formed by the "Abstract Digest", which is a summary of all abstracts submitted to and found by the editors of relevance to the field of Active B Stars. It is published, and publicized through our mailing list, when about 10 to 15 abstracts have accumulated, special issues are made when e.g. conference proceeding deadlines increase the number of abstracts temporarily. After four weeks, each digest has between 50 and 100 views, with the announcement having been sent to about 190 maii addresses (see above). A second important component of the new BeSN concept are the "Talk Recordings". We welcome individual talks, but the backbone of this section will be conference recordings. The first conference to upload videos was Bright Emissaries 2014 held in London/Ontario. Four weeks after announcing the availability of the videos, each talk has typically been viewed between 10 and 20 times. A second meeting, the BeXRB 2014 workshop in Valencia has recorded its talks and will submit them to us soon. We also offer technical support in editing and recoding the videos for meeting organizers. A third  part is the "Discussion Forum". While abstract digest and talk recordings have reached their expected activity levels, the discussion forum requires some more work. The section on the OHANA project has shown the prospect to have a group of regular readers, but contributors are still missing. The next steps here are described below in the section the WGABS' relation to amateur astronomers.

Invited Reviews and policy documents

The WGABS has coordinated and supported two invited reviews on Be stars since 2000, first Porter & Rivinius, 2003, and more recently Rivinius, Carciofi, and Martayan, 2013. Members and former members of the WGABS OC who have been asked to contribute to documents like white books, instrument and mission proposals and other such efforts usually circulate their contribution drafts among the current OC.

Observational Advances Relevant to the Field of Active B Stars

  • B[e] stars, LBVs in quiescence (which have B supergiant type spectra), binaries among early type stars
  • Space photometry projects like CoRoT, KEPLER, K2, BRITE, but also GAIA
  • Ground photometry providing long strings of data of many objects (OGLE, VST surveys)
  • Interferometry with current and future instruments and facilities
  • Dedicated projects like BeSOS
  • Linear broad-band and spectropolarimetry of circumstellar environments

Theoretical and Computational Advances

  • Supercomputers, Hydro- and Monte Carlo codes
  • Use of the Virtual Observatory (VO)
  • Increasing understanding of polarizing processes.
  • Handle to viscosity acting in the CS environments

Relation to Commissions and Working Groups

Concerning Working Groups, several interesting proposals were discussed during the LoI phase, however, at this point none of them is ready for a committement and are there not added here. In general, we note that under the new guidelines,  WGs are not meant to be long-term standing bodies, but rather study well-defined scientific issues and report to the Commission. Unless specifically re-appointed by the same procedure, such Working Groups cease to exist at the next following General Assembly.


Working Groups [need to have] particular short-term or long-term deliverables

Concerning Commissions, relations to other (proposed) commissions were mainly explored with the Proposed Commission on Massive Stars and Stellar Magnetism, through discussion with individual OC members/proposer. However, there is as well some topical opverlap with other proposed commissions as described below:

  • Massive Stars: Overlap exists concerning the earliest main sequence B stars (above 8 solar masses at the ZAMS) and supergiants. The Massive Star community, however, in the past few years, has evolved a focus interest in the most massive objects, which are far out of the scope of active B stars, including some quite distinctly different regimes of physical processes. We will maintain our current cordial relations with a Commission on Massive Stars.
  • Stellar Magnetism: The topical overlap with this proposed Commission are magnetospheres, and ongoing discussions may lead to the proposal of a joint Working Group.
  • Binary Stars: Current Commissions 26 and 42 propose a merged Commission on Binary Stars. As with Stellar Magentism, there is a topical overlap in the field of X-Ray binaries, however, no discussions are currently ongoing.
  • Interferometry: Commission 54 will re-apply for commission status. We note that active B stars are a major target group for optical and infrared interferometers, and consequently a Commission on Active B Stars would have a vital interest in establishing links to a Commission on Interferometry.

Relation to Amateur Astronomers

Many of the stars visible in the sky with naked eye are active B stars. This explains a particularly strong amateur interest in our field, contributing to a ``hands on'' popularization of the science of astronomy. As amateur instruments nowadays reach professional capabilities when observing bright stars (e.g. medium resolution echelle spectroscopy, CCD-photometry), professional-amateur collaborations have become fairly frequent. Recent examples are the 2011 periastron of delta Sco (Miroshnichenko et al., 2013, ApJ 766, 119) or Halpha Doppler tomography of the Be binary star pi Aqr (Zharikov et al., 2013, A&A 560, A30). The WGABS acknowledges this by offering dedicated sections of our discussion forum, aimed at amateur and professional astronomers to initiate collaborations, e.g. via observing alerts, and by publishing observational results obtained by amateurs in the BeSN.

The BeSS database hosts spectra of Active B stars (mostly Be stars) submitted by amateurs. Typically about 100 spectra per month are uploaded, and a monthly activity report is compiled. Given the variability properties of Active B stars, this continuous spectroscopic coverage is a huge asset for the professional community, where detailed studies based on high-quality snapshots often suffer from an unknown variability history. The WGABS promotes this effort by re-distributing the monthly activity reports and enabling comments on them. This also serves as a re-vival of the former "What's Happening?" section of the BeSN.


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