J/ApJ/686/1280 Discovery of hot subdwarf companion to FY CMa (Peters+, 2008)
Detection of a hot subdwarf companion to the Be star FY Canis Majoris.
Peters G.J., Gies D.R., Grundstrom E.D., McSwain M.V.
<Astrophys. J., 686, 1280-1291 (2008)>
=2008ApJ...686.1280P 2008ApJ...686.1280P
ADC_Keywords: Stars, Be ; Binaries, spectroscopic ; Stars, subdwarf ;
Spectra, ultraviolet ; Radial velocities ; Equivalent widths
Keywords: binaries: spectroscopic - stars: emission-line, Be - stars:
evolution - stars: individual (HR 2855, HD 58978, FY CMa) - subdwarfs
Abstract:
The rapid rotation of Be stars may be caused in some cases by past
mass and angular momentum accretion in an interacting binary in which
the mass donor is currently viewed as a small, hot subdwarf stripped
of its outer envelope. Here we report on the spectroscopic detection
of such a subdwarf in the Be binary system FY Canis Majoris from the
analysis of data acquired by the IUE spacecraft and KPNO Coude Feed
Telescope over the course of 16 and 21yr, respectively. We present a
double-lined spectroscopic orbit for the binary based on radial
velocities from the IUE spectra and use the orbital solutions with a
Doppler tomography algorithm to reconstruct the components' UV
spectra. The subdwarf is hot (Teff=45±5kK) and has a mass of about
1.3M☉ and a radius of about 0.6R☉. It contributes about 4%
as much flux as the Be star does in the FUV. We also present
observations of the Hα and HeIλ6678 emission features
that are formed in the circumstellar disk of the Be star.
Description:
Ninety-seven high-resolution far-ultraviolet (FUV) spectra were
obtained with IUE over the period from 1979 to 1995.
We also obtained 158 red spectra of FY CMa with the Kitt Peak National
Observatory (KPNO) 0.9m Coude Feed Telescope between 1985 and 2006.
Objects:
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RA (2000) DE Designation(s) Period (P)
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07 26 59.5 -23 05 10 FY CMa = HR 2855 = HD 58978 ; P=37.26d
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 59 97 IUE radial velocity measurements
table5.dat 39 158 Red spectra measurements
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 F11.3 d Date HJD
13- 22 A10 "YYYY/MM/DD" ObsDate Observation date UT
23- 28 I6 --- SWP IUE Short-Wavelength Prime (SWP) number
29- 34 F6.3 --- Phase Orbital phase from Be star superior
conjunction
35- 40 F6.1 km/s HRV1 Heliocentric radial velocity for Be star
41- 46 F6.1 km/s O-C1 Observed minus calculated velocity for Be star
47- 53 F7.1 km/s HRV2 ? Heliocentric radial velocity for subdwarf
54- 59 F6.1 km/s O-C2 ? Observed minus calculated velocity for
subdwarf
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 11 F11.3 d Date HJD
13- 17 F5.3 --- Phase Orbital phase from Be star superior conjunction
19- 24 F6.2 0.1nm EW Hα equivalent width in Angstroms
26- 30 F5.1 km/s HRV(Ha) Heliocentric radial velocity Hα wings (1)
32- 35 I4 km/s HRV(He) ? Heliocentric velocity of HeI peaks (6678Å)
37- 39 I3 km/s DRV(He) ? HeI peak velocity separation
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Note (1): HRV(Ha) values omitted in Fig. 1 and in the orbital solution of
Table 3, column 2, for HJD-2400000=47639.671 and 47983.611.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 06-Jan-2011