Optical spectroscopy of close companions to nearby Herbig Ae / Be and T Tauri stars ⋆

Content Provider	Semantic Scholar
Copyright Year	2007
Abstract	We present VLT-FORS2 optical (5700 9400 Å) spectroscopy of cl se (r < 1.5”) companions to three nearby (d < 200 pc) Herbig Ae/Be stars (HD 144432, HD 150193, KK Oph) and one T Tauri star (S C rA). We report the detection of Li I (6707 Å) in absorption and emission lines (H α, Ca II triplet) in the spectra of the companions. Our observa tions strongly suggest that the companions are physically associated premain-sequence stars. The spectral type derived for the comp anions is K5Ve for HD 144432 B, F9Ve for HD 150193 B, and G6Ve for KK Oph B. S CrA A and B were observed simultaneously. The spatially resolved spectra indicate that S CrA A (primar y, north) is a G star and that S CrA B (secondary, south) is a K st ar. Using photometry from the literature and estimations of the RandI magnitude derived from the spectra, we localized primaries and companions in the HR diagram, derived their masses and as suming coevality constrained the age of the systems. KK Oph B (7 Myr) and S CrA B (2 Myr) are actively accreting T Tauri star s nd are very likely surrounded by disks. HD 150193 B (10 Myr) and HD 144432 B (8 Myr) are weak-line T Tauri stars. Three of the four systems studied (HD 144432, HD 150193, KK Oph) have ages > 7 Myr. These systems retained their disks for a longer time th an ypical of a young star. Our results suggest that binarity may be a key issue in understanding the lifetim of disks.
File Format	PDF HTM / HTML
Alternate Webpage(s)	http://arxiv.org/pdf/astro-ph/0701208v1.pdf
Alternate Webpage(s)	http://cds.cern.ch/record/1009199/files/0701208.pdf
Language	English
Access Restriction	Open
Subject Keyword	ABRA gene Anions Ar (Unix) Calcium Diagram Disk storage GUCY2C protein, human Lithium Photometry Star Trek: Stars, Celestial Stellar classification Triplet state Virtual Link Trunking stage IV childhood Hodgkin's lymphoma
Content Type	Text
Resource Type	Article