Spectroscopic analysis of the B/Be visual binary HR 1847 ^*,**

¹ Astronomický ústav, Akademie věd České republiky, 251 65 Ondřejov, Czech Republic e-mail: kubat@sunstel.asu.cas.cz
² National Research Institute of Astronomy and Geophysics, 11421 Helwan, Cairo, Egypt
³ Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko Shossee Blvd., 1784 Sofia, Bulgaria
⁴ Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, CEA, IRFU, SAp, Centre de Saclay, 91191 Gif-sur-Yvette, France
⁵ Astronomický ústav, Akademie věd České republiky, Boční II 1401, 141 31 Praha 4, Czech Republic
⁶ Ústav teoretické fyziky a astrofyziky PřF MU, Kotlářská 2, 611 37 Brno, Czech Republic

Received: 24 November 2009
Accepted: 22 May 2010

Abstract

We studied both components of a slightly overlooked visual binary HR 1847 spectroscopically to determine its basic physical and orbital parameters. Basic stellar parameters were determined by comparing synthetic spectra to the observed echelle spectra, which cover both the optical and near-IR regions. New observations of this system used the Ondřejov and Rozhen 2-m telescopes and their coudé spectrographs. Radial velocities from individual spectra were measured and then analysed with the code FOTEL to determine orbital parameters. The spectroscopic orbit of HR 1847A is presented for the first time. It is a single-lined spectroscopic binary with a B-type primary, a period of 719.79 days, and a highly eccentric orbit with e=0.7. We confirmed that HR 1847B is a Be star. Its Hα emission significantly decreased from 2003 to 2008. Both components have a spectral type B7-8 and luminosity class IV-V.