Bibcode
Kun, M.; Martin, E. L.
Referencia bibliográfica
Astronomy and Astrophysics Supplement, v.116, p.467-471
Fecha de publicación:
5
1996
Número de citas
38
Número de citas referidas
30
Descripción
We present mid-resolution spectroscopic observations of 63 faint
(V=12-16) stars identified by Kun (1992) as Hα emission candidates
in an objective prism survey of several high galactic latitude molecular
clouds. Only 4 stars in our sample (6%) are bona fide T Tauri stars on
the basis of their strong Li I absorption and Hα emission
features. They have late M spectral types (M4-M5.5) and two of them form
a visual binary with separation ~7". The new T Tauris are associated
with the L 134 molecular complex, the northernmost extension of the
Scorpio - Ophiuchus star forming region, which has been traditionally
considered as a non-star forming region. In the other high latitude
clouds surveyed by Kun (1992), we have not found any T Tauri star in our
follow-up spectroscopy. Most of the observed stars (~80%) are late type
dwarfs without detectable Hα emission in our spectra. Eight stars
are M-dwarfs with Hα in emission, but no detectable Li I
λ6708 absorption. They could be post T Tauri stars or older dMe
stars; more data is necessary in order to establish their evolutionary
status. Our results show that Kun (1992) was able to detect weak
Hα emission lines (down to equivalent width of ~1.5A) in faint
stars near the plate magnitude limit (V~16), but in many cases plate
defects, absorption bands and/or overlying stars were taken as possible
Hα emission. In this paper we correct Kun's previous indication
that there may be numerous young stars associated to high latitude
molecular clouds, and we severely constrain the presence of a population
of T Tauri stars in these clouds. We note that none of our four T Tauri
stars is located in an isolated translucent molecular cloud.