J/MNRAS/437/2303 Radial velocity curves of alpha Lib A (Fuhrmann+, 2014)
On the bright A-type star alpha Librae A.
Fuhrmann K., Chini R., Barr A., Buda L.-S., Kaderhandt L., Pozo F.,
Ramolla M.
<Mon. Not. R. Astron. Soc., 437, 2303-2306 (2014)>
=2014MNRAS.437.2303F 2014MNRAS.437.2303F (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, spectroscopic ; Radial velocities
Keywords: binaries: spectroscopic - stars: individual: alpha Lib A -
stars: rotation
Abstract:
The spectroscopy of rapidly rotating binary stars occasionally
encounters systems where - paradoxically - the primary is effectively
hidden in the light of its secondary. Here, we report on a bright
textbook example of this kind with the nearby A-type star α Lib
A. Although discovered as a spectroscopic binary already in the year
1904, a radial velocity curve has never been published up to a point
where the existence of the secondary became even suspicious. However,
in this work, we demonstrate that α Lib A is indeed a
double-lined spectroscopic binary with a rapidly rotating - and hence
almost invisible - A-type primary, accompanied and predominated by a
more slowly rotating late-A or early F-type secondary in an eccentric
P=70.34d orbit. On account of the shallow absorption lines of
the primary, uncertainties remain with its semi-amplitude and hence
the exact mass ratio. Yet, with a maximal projected separation that
should lie in the range 20 to 25mas, follow-up high-angular
resolution observations might soon establish α Lib Aa-Ab as a
visual binary, with a measure for the orbital inclination and
precisely determined stellar masses.
Description:
Our observations of α Lib A consist of optical spectra secured
with the BESO high-resolution echelle spectrograph of the
Universitetssternwarte Bochum near Cerro Armazones in Chile. The full
record of the total of 55 radial velocities is given in Table 1.
Intense Doppler-monitoring of alpha Lib A started in 2012 August and
was continued until 2013 September.
Objects:
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RA (2000) DE Designation(s)
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14 50 52.71 -16 02 30.4 alpha Lib A = HR 5531
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 31 55 Radial velocity measurements of alpha Lib A
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 d JD Julian date (JD-2450000)
11- 15 F5.1 km/s RVAa Aa component radial velocity
17- 19 F3.1 km/s e_RVAa rms uncertainty on RVAa
21- 26 F6.2 km/s RVAb Ab component radial velocity
28- 31 F4.2 km/s e_RVAb rms uncertainty on RVAb
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 10-Mar-2015