BRITE-Constellation Mission Update

By / par Catherine Lovekin (Canadian PI for BRITE)
(Cassiopeia – Autumn / l’automne 2020)

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 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 Sagittarius VI field, revisiting this field for the sixth 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 is currently observing a target of opportunity.
  • BRITE Austria (Austria): BRITE Austria observes with a red filter. It is currently observing the Sagittarius VI field.
  • UniBRITE (Austria): Currently out of order.

The BRITE Constellation observing program is currently set through the end of 2020, and the program for 2021 will be finalized by the BRITE Executive Science Team (BEST) in the next few weeks. Details of the observing plan will be available on the BRITE photometry Wiki page.

Recent Science Results

“Direct evidence for shock-powered optical emission in a nova” (Aydi et al., 2020, NatAs, 4, 776).

It has long been thought that the luminosity of classical novae is powered by continued nuclear burning on the surface of the white dwarf after the initial runaway. However, recent observations of high energy γ-rays from classical novae have hinted that shocks internal to the nova ejecta may dominate the nova emission. Shocks have also been suggested to power the luminosity of events as diverse as stellar mergers, supernovae and tidal disruption events, but observational confirmation has been lacking. Aydi et. al. report simultaneous space-based optical and γ-ray observations of the 2018 nova V906 Carinae (ASASSN-18fv), revealing a remarkable series of distinct correlated flares in both bands. The optical and γ-ray flares occur simultaneously, implying a common origin in shocks. During the flares, the nova luminosity doubles, implying that the bulk of the luminosity is shock powered. They detect concurrent but weak X-ray emission from deeply embedded shocks, confirming that the shock power does not appear in the X-ray band and supporting its emergence at longer wavelengths. Combining the BRITE data with observations spanning the spectrum from radio to γ-ray, Aydi et. al. provide direct evidence that shocks can power substantial luminosity in classical novae and other optical transients.

Figure 1. The optical and GeV γ-ray light curves of Nova V906 Car are correlated, showing simultaneous flares in both bands. The black dashed lines represent the dates of the post-maximum flares. The green arrow indicates the date of the first NuSTAR X-ray observation. The black solid bar indicates the period of Fermi/LAT down time due to technical issues. Fermi entered another observing gap between days 46 and 57. The error bars in the BRITE light curve are 1σ uncertainties. The point-to-point scatter of the binned BRITE measurements is≈2 mmag and therefore the size of the error bars is smaller than the symbol size. The error bars in the Fermi light curve are 1σ uncertainties. The eruption start is on 2018 March 16.03 UT. From Aydi et al. (2020).

Conferences, Resources, and Social Media

Conferences

The BRITE team did not host any conferences this year. The proceedings from the 2019 conference “Stars and their Variability Observed from Space” have now been published and all papers are available online here.

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 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 Konstanze Zwintz, the chair of BEST at konstanze.zwintz@uibk.ac.at.

Bookmark the permalink.

Comments are closed.