Radial velocities of Hipparcos southern B8-F2 type stars

Abstract

Abstract. Radial velocities have been determined for a sample of B8-F2 type stars observed by the Hipparcos satellite. Observations were obtained within the framework of an ESO key-program. Radial velocities have been measured using a cross-correlation method, the templates being a grid of synthetic spectra. The obtained precision depends on effective temperature and projected rotational velocity of the star as well as on a possible asymmetry of the correlation peak generally due to secondary components. New spectroscopic binaries have been detected from these asymmetries and the variability of the measured radial velocity. Simulations of binary and triple systems have been performed. For binaries our results have been compared with Hipparcos binary data. Adding the variable radial velocities, the minimum binary fraction has been found 60% for physical systems. Radial velocities have been determined for 581 B8-F2 stars, 159 being new. Taking into account published radial velocities, 39% south A-type stars with V magnitude lower than 7.5 have a radial velocity.

Rotational velocities of A-type stars

“…4, 5, 6 give respectively the derived value of v sin i, the associated standard deviation and the corresponding number of measured lines (uncertain v sin i are indicated by a colon), Col. 7 presents possible remarks about the spectra: SB2 ("SB") and shell ("SH") natures are indicated for stars detailed in the subsections which follow, as well as the reason why v sin i is uncertain -"NO" for no selected lines, "SS" for variation from spectrum to spectrum and "LL" for variation from line to line, as detailed in the Appendix A. Grenier et al (1999) studied the same stars with the same spectra and derived radial velocities using crosscorrelation techniques. On the basis of the shape of the cross-correlation function (CCF) they find that less than half of the sample has a symmetric and Gaussian CCF and they classify stars with distorted CCF as, among other things, "certain" "probable" or "suspected" doubles.…”

“…The results for these objects are detailed below. These objects were either known as binaries or newly detected by Grenier et al (1999).…”

“…It is worth noticing that the spectra which are the subject of the present paper were also studied by Grenier et al (1999) to derive radial velocities, and that the 71 A0 dwarf stars observed were investigated by Gerbaldi et al (1999). Basically, this sample includes objects with no radial velocity or only for one epoch.…”

“…Some stars with no v sin i determination were added from the Bright Star Catalogue (Hoffleit & Jaschek 1982). The observational programme is more detailed by Grenier et al (1999).…”

The multiplicity ofφPhe revisited

“…Leone & Catanzaro (1999) completed the dataset and derived the first spectroscopic orbit (e = 0.32, P = 41.489 days). Grenier et al (1999) also complemented the dataset with one more radial velocity, but did not derive any orbit. In the original reduction of the Hipparcos data (ESA 1997), a circular nearly edge-on 878-day orbit was derived from the sole astrometric observations.…”