BRITE-Science

Starting point / motivation

BRITE-Constellation is currently the ONLY operative and active stellar space photometry mission, as all similar missions, like MOST and CoRoT are no longer operative, or Kepler’s operation had to be reduced to a two-wheel mode (K2). On top of that, BRITE-Constellation will be the ONLY space mission that is able to observe ß-Pictoris and monitor continuously in 2017 the predicted transit of the planet through the star’s Hill sphere (i.e., a dusty ring system).

These observations will allow us to learn more about the formation of stars and planets and, hence, we can contribute to one of the important questions of society: where do we come from and is the Earth a unique place in the Universe?

BRITE-Constellation is a demanding scientific project, never done before and had a consid-erable response in the scientific community, confirming first class science potential. The performance of BRITE-Constellation in orbit clearly exceeds the technical mission requirements. BRITE is more precise than SMEI, provides longer time bases than MOST, and its targets are much better known stars than those observed by Kepler or CoRoT will ever be.

Contents and goals

Delivery of "ready to use" data to the BRITE community is a prime goal of the current proposal. A very challenging task is to translate the observing program developed on scientific grounds to commands which control the pointing and data acquisition details, which are subject to constraints and changing over time.

On the science side, the strong theoretical context of BRITE-Constellation has to be stressed. There is no lack of hypotheses, but lack of hard facts, as lots of free parameters allow only sub-optimal, ambiguous modelling. Hence observational checks with high-quality data are extremely important! These BRITE data will help scientists to investigate the nature of the stars observed regarding a variety of different physical processes.

The current proposal focuses on selected scientific topics that address some of the most prominent open questions in stellar astrophysics: 

• rotation at the surface and its evolution in the interior,
• pulsation and interaction with circumstellar disks,
• the young star ß Pictoris - a showcase for planet formation,
• regular g-mode period spacings in Doradus stars for testing internal stellar structures, and
• the role of stellar magnetic fields.

BRITE photometry provided so far for the first time:

• strong evidence for Be stars that the coupling of the two strongest modes leads to periodically enhanced star-to-disk mass-transfer rates;
• constraints for the decoupling of the angular momentum between stellar core and envelope, as indicated by the BRITE data of HD 201433;
• large time base data of the Doradus star 43 Cygni showing a clear g-mode period spacing pattern that will allow i.a. the determination of the star’s rotation profile;
• observation data of a Cir, one of the best roAp stars to constrain pulsation models in the presence of a magnetic field and their temporal stability, as was demonstrated with the very first BRITE science data obtained after commissioning of the constellation.

Coordinator

Graz University of Technology, Institute for Communication Networks and Satellite Communication

Project partner

• University of Innsbruck, Institute for Astro- and Particle Physics
• University of Vienna, Institute for Astrophysics

Graz University of Technology
Institute for Communication Networks and
Satellite Communication
Univ. Prof. DI Dr. Otto Koudelka
Inffeldgasse 12
A-8010 Graz