J/ApJ/765/2 FUV radial velocities of 59 Cyg (Peters+, 2013)
Far-ultraviolet detection of the suspected subdwarf companion to the
Be star 59 Cygni.
Peters G.J., Pewett T.D., Gies D.R., Touhami Y.N., Grundstrom E.D.
<Astrophys. J., 765, 2 (2013)>
=2013ApJ...765....2P 2013ApJ...765....2P
ADC_Keywords: Stars, Be ; Radial velocities ; Ultraviolet
Keywords: binaries: spectroscopic; stars: emission-line, Be; stars: evolution;
stars: individual: BD +75 325; subdwarfs;
stars: individual (HR 8047,HD 200120,59 Cyg)
Abstract:
We report on the detection of a hot subdwarf component in the Be
binary system, 59 Cygni. The spectral signature is found in
cross-correlation functions of photospheric model spectra with
far-ultraviolet spectra obtained by the International Ultraviolet
Explorer Satellite, and we used radial velocities from the
cross-correlation functions to determine a double-lined spectroscopic
orbit. The individual spectra of the binary components were extracted
using a Doppler tomography algorithm. The flux of the system is
dominated by the rapidly rotating Be star. However, the subdwarf
contributes approximately 4% of the UV flux, and its spectrum bears a
strong resemblance to that of the hot sdO star BD +75°325. Based
on the appearance of the UV spectrum and the orbital elements, we
present estimates for the stellar masses, radii, and temperatures. The
presence of the hot companion causes excess emission from the outer
part of the Be disk facing the companion. We present a set of red
spectra that show the orbital phase variations of the He I
λ6678 emission formed in the heated region of the disk, which
probably occurs near the disk outer boundary. 59 Cygni, FY Canis
Majoris, and φ Persei comprise the known set of Be binaries with
detected hot evolved companions, which are the stripped down remains
of mass transfer. Their properties demonstrate that some fraction of
Be stars were spun up through angular momentum transfer by Roche lobe
overflow.
Description:
We obtained the UV spectra of 59 Cyg from the NASA Mikulski Archive
for Space Telescopes. The selection focused on observations made with
the IUE High Resolution Echelle Spectrometer, short-wavelength prime
(SWP) camera, which recorded the far-UV spectrum with a resolving
power of R=10000. There are a total of 194 such observations that were
made between 1978 and 1994. We further limited this sample to the 157
spectra with the best signal-to-noise ratio (S/N) (usually >10 in the
better-exposed parts of the spectrum).
Objects:
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RA (ICRS) DE Designation(s) (Period)
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20 59 49.56 +47 31 15.4 * 59 Cyg = HD 200120 (P=28.2)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 66 157 IUE radial velocity measurements
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See also:
VI/110 : Final Merged Log of IUE Observations (NASA-ESA, 2000)
B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2014)
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
III/23 : MK Classification for OB Stars (Lesh 1968)
J/AJ/146/76 : Astrometry & phot. of UCAC4 double stars (Hartkopf+, 2013)
J/A+A/546/A61 : Radial velocities for XHIP catalogue (de Bruijne+, 2012)
J/ApJS/187/228 : Hα profiles of Be stars (Silaj+, 2010)
J/AJ/137/3358 : Speckle interferometry of massive stars (Mason+, 2009)
J/A+A/440/305 : Parameters of fast-rotating B stars (Fremat+, 2005)
J/ApJ/573/359 : Rotational velocities of B stars from BSC (Abt+, 2002)
J/A+A/387/580 : UBV photometry of V832 Cyg (Harmanec+, 2002)
J/A+A/381/446 : Astrometric Radial Velocities. III. (Madsen+, 2002)
J/A+A/378/861 : Spectroscopy of Be stars (Chauville+, 2001)
J/A+A/368/912 : Polarization & rotational velocities of Be stars (Yudin, 2001)
J/AJ/119/3084 : ICCD speckle obs. of binary stars. XXIII. (Hartkopf+, 2000)
J/A+AS/129/289 : Long-term spectrophotometry of Be stars (Moujtahid+ 1998)
J/A+AS/105/305 : OB stars observed with high dispersion by IUE (Bohlin+ 1994)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d HJD HJD of mid-observation; HJD-2400000
11- 20 A10 "YYYY/MM/DD" Date UT date of observation
22- 26 I5 --- SWP IUE short-wavelength prime (SWP) number of
observation
28- 32 F5.3 --- Phase Orbital phase of observation
34- 38 F5.1 km/s HRV1 [-27/33] Heliocentric radial velocity
of star 1 (Be star)
40- 42 F3.1 km/s e_HRV1 Uncertainty in HRV1
44- 48 F5.1 km/s (O-C)1 Observed minus calculated residual of
star 1
50- 55 F6.1 km/s HRV2 [-149/123]? Heliocentric radial
velocity of star 2 (hot companion)
57- 60 F4.1 km/s e_HRV2 ? Uncertainty in HRV2
62- 66 F5.1 km/s (O-C)2 ? Observed minus calculated residual of
star 2
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 28-Oct-2014