Except 5 stars for which the signal to noise ratio was too poor, for the 21 remaining stars, the S/N ratio between 20 and 200 was good enough to be able to conclude on the presence or absence of the Ca II absorption feature at the stellar radial velocity. With an expected FWHM similar to the Ca II Pictoris line ( km s-1), such feature can be separated from the photospheric absorption of the program stars ( km s-1). We did not detect any Ca II absorption out of the noise level. Table 1 lists the target stars and gives the corresponding upper limits on the equivalent width of Ca II. These must be compared to the equivalent width of the stable Ca II -K absorption toward Pictoris: mÅ .
Table 1. Program stars with their upper limit for the equivalent width of the Ca II -K absorption line () at the stellar velocity. These are to be compared to the mÅ observed toward Pictoris . The references (Ref.) are: (1) Eggen (1983); (2) Eggen (1984); (3) Eggen (1986); (4) Palous & Hauck (1986); (5) Hoffleit & Warren (1991).
© European Southern Observatory (ESO) 1997
Online publication: March 26, 1998