Researchers (see list of participants) from different Institutes in São Paulo, Minas Gerais and Rio de Janeiro are involved with pre-main sequence stars (PMSs) projects related to the Brazilian participation in the COROT satellite.
Our group has a large experience with surveys and detailed analysis of PMSs, Star Forming Regions, and Young Stellar Associations (see abstracts of relevant papers). Hundreds of young objects have been identified by us based on spectroscopy, optical and near-infrared photometry, and the ratio of X-ray/optical luminosities and X-ray hardness ratio. These objects are mainly T Tauri stars, classical (CTT) and weak (WTT); Herbig Ae/Be stars (HAeBes); and Fe/Ge PMSs. The spectra of some of these, previously studied in detail by us, exhibit emission and absorption lines that show substantial variety and variability in shape. The accretion-related lines may show both outflow and infall signatures. The photometric and spectroscopic variability of the objects have timescales ranging from a few hours to several weeks. The PMS stars present a rich variety of variability types, which includes pulsation, hot and cold spots, higher modes of vibrations, stellar multiplicity, accretion processes, jets, disk debris passing in front of the star, Algol-type occultation, etc.
We have selected possible candidates (see list of objects) to be observed with the COROT Additional Program, for which we have projects focused on the following scientific goals:
1. Variability in PMS: (i) to study the interaction of the star with the circumstellar structure; (ii) to verify the variability produced by hotspots; (iii) to search for eclipses by circumstellar material and/or other periodic variations; (iv) to model the variations in the accretion process; (v) to verify the presence of giant protocomets, etc.
2. Post-T Tauri stars and Protoplanets: to observe selected post-T Tauri stars with ages between 5 and 30Myr, in order to detect cloud-type particle structures belonging to their disks. These swarms of particles can have the form of ring segments or could be embryos of planetesimals or dust, which is captured by resonance around planets. The measurement of their rotation periods and the duration of their transits will provide the sizes of these structures and their distances to the stars.
See also: Members Publications Targets Workshop in Natal
Contact:
jane@astro.iag.usp.br
Jane
Gregorio-Hetem
IAG/USP
Rua do Matão, 1226 - Cidade
Universitária
05508-090 - São Paulo, SP,
Brazil
phone: (55 11) 3091 2823 FAX: (55 11) 3091 2860