Issue |
Astron. Astrophys. Suppl. Ser.
Volume 116, Number 3, May 1 1996
|
|
---|---|---|
Page(s) | 467 - 471 | |
DOI | https://doi.org/10.1051/aas:1996129 | |
Published online | 15 May 1996 |
Spectroscopy of possible Hα emission stars in regions of high galactic latitude molecular clouds*
1
Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
2
and Konkoly Observatory, P.O. Box 67, H-1525 Budapest, Hungary
Send offprint request to: E.L. Martín
Received:
26
January
1995
Accepted:
9
October
1995
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 . 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 ~ 1.5 Å)
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.
Key words: stars: pre-main sequence / stars: emission line / surveys
© European Southern Observatory (ESO), 1996