Aj. Delgado et al., Spectroscopy of pre-main-sequence candidates of spectral type AF in the young Galactic cluster IC 4996, ASTRONOM J, 118(4), 1999, pp. 1759-1765
We present the results of a spectroscopic analysis of the pre-main-sequence
(PMS) candidates in IC 4996, proposed by Delgado et al. Spectral types and
heliocentric radial velocities are calculated for 16 stars in the held obs
erved by these authors, 13 of them located in the region of the color-magni
tude diagram where their proposed PMS stars are located. The estimated heli
ocentric radial velocity of the cluster is centered around -12 +/- 5 km s(-
1). From the radial velocity distribution, six stars are rejected as cluste
r members, one of them showing spectral features characteristic of an Am st
ar. The remaining 10 stars are confirmed as cluster members: three B-type s
tars and seven PMS stars of spectral types A4-F0 (six stars) and early G (o
ne star). One of the proposed PMS members clearly shows radial velocity and
spectral type variations, as well as relatively broad Her absorption. The
G-type cluster member is a weak-lined T Tauri star with strong Li I gamma 6
708 absorption [W-lambda(Li I) similar or equal to 0.26 Angstrom]. These re
sults strongly support the presence in the cluster of a populated sequence
of PMS stars of AF spectral type.