BRITE-Constellation Mission Update

By/par Gregg Wade, Canadian PI for BRITE
(Cassiopeia – Spring/printemps 2018)

BRITEpatch

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 22 data releases to BRITE target PIs having already taken place, and many datasets available in the public domain from the BRITE public archive.

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, Bishop’s 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. Recent approval of continued operations funding of BRITE-Toronto by CSA will ensure the Canadian mission until at least January 2019.

Operations

There are five operating BRITE satellites in the Constellation, collecting data on various sky fields in a coordinated programme to obtain well-sampled, longterm continuous (~6 months) light curves in both red and blue bandpasses.

As this issue of Cassiopeia went to press, here was the status of the sky assignments for the BRITE cubesats:

  • BRITE Toronto (Canada): Toronto observes with a red filter. It is currently observing the Carina II field. As implied by the numeral ‘II’, the current campaign on Carina represents a revisit of a previously-observed field.
  • BRITE Lem (Poland): Lem observes with a blue filter. It is observing the Centaurus II field.
  • BRITE Heweliusz (Poland): Heweliusz observes with a red filter. This satellite is observing Vela/Pictoris III field.
  • BRITE Austria (Austria): BRITE Austria observes with a blue filter. It is observing the Vela/Puppis IV and the Centaurus II fields, switching between the two fields each orbit.
  • UniBRITE (Austria): UniBRITE observes with a red filter. This satellite is also currently observing the Vela/Puppis IV and the Centaurus II fields.

The BRITE Constellation observing programme from early 2017 through early 2019 has been planned by the BRITE Executive Science Team (BEST), and details are available on the BRITE photometry Wiki page.

Recent Science Results

Light curves of η Car observed by BRITE in 2016 (left) and 2017 (right). The data points are solid circles (•; BTr), plus signs (+; UBr), and open diamonds (♦; BHr) with the two-frequency fit shown in red. Each panel shows 180 d of time on the abscissa, with nearly 180 d between the two panels. A typical 2 mmag error bar (2σ) are shown in the lower left part of the panels. From Richardson et al. (2018).

Light curves of η Car observed by BRITE in 2016 (left) and 2017 (right). The data points are solid circles (•; BTr), plus signs (+; UBr), and open diamonds (♦; BHr) with the two-frequency fit shown in red. Each panel shows 180 d of time on the abscissa, with nearly 180 d between the two panels. A typical 2 mmag error bar (2σ) are shown in the lower left part of the panels. From Richardson et al. (2018).

BRITE-Constellation reveals evidence for pulsations in the enigmatic binary η Carinae” (Richardson et al. 2018, MNRAS 475, 5417):
η Car is a massive, eccentric binary with a rich observational history. Richardson et al. report the first high-cadence, high-precision light curves obtained with the BRITE-Constellation nanosatellites over 6 months in 2016 and 6 months in 2017. The light curve is contaminated by several sources including the Homunculus nebula and neighbouring stars, including the eclipsing binary CPD -59°2628. However, they find two coherent oscillations in the light curve. These may represent pulsations that are not yet understood but they postulate are related to tidally excited oscillations of η Car’s primary star, and would be similar to those detected in lower mass eccentric binaries. In particular, one frequency was previously detected by van Genderen et al. and Sterken et al. through the time period of 1974-1995 via timing measurements of photometric maxima. Thus, this frequency seems to have been detected for nearly four decades, indicating that it has been stable in frequency over this time span. These pulsations could help provide the first direct constraints on the fundamental parameters of the primary star if confirmed and refined with future observations.

Conferences, Resources and Social Media

Conferences

The proceedings of the second BRITE Science Conference – held in Innsbruck, Austria in 2016 – are available in printed form and online.

Resources

The BRITE Public Data Archive, based in Warsaw, Poland, at the Nikolaus Copernicus Astronomical Centre, can be accessed at brite.camk.edu.pl/pub/index.html.

The mission Wiki (including information on past, current and future fields) can be accessed at brite.craq-astro.ca/.

BRITE Constellation is now 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 to join BIAST, contact Canadian BRITE PI Gregg Wade: wade-g@rmc.ca.

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