J/ApJ/836/112 High-resolution spectra of * bet CMi (Dulaney+, 2017)
A spectroscopic orbit for the late-type Be star β CMi.
Dulaney N.A., Richardson N.D., Gerhartz C.J., Bjorkman J.E., Bjorkman K.S.,
Carciofi A.C., Klement R., Wang L., Morrison N.D., Bratcher A.D.,
Greco J.J., Hardegree-Ullman K.K., Lembryk L., Oswald W.L., Trucks J.L.
<Astrophys. J., 836, 112-112 (2017)>
=2017ApJ...836..112D 2017ApJ...836..112D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, Be ; Stars, double and multiple ; Stars, late-type ;
Radial velocities ; Spectroscopy
Keywords: binaries: spectroscopic; stars: emission-line, Be;
stars: individual: * bet CMi
Abstract:
The late-type Be star β CMi is remarkably stable compared to
other Be stars that have been studied. This has led to a realistic
model of the outflowing Be disk by Klement+ (2015A&A...584A..85K 2015A&A...584A..85K).
These results showed that the disk is likely truncated at a finite
radius from the star, which Klement et al. suggest is evidence for an
unseen binary companion in orbit. Here we report on an analysis of the
Ritter Observatory spectroscopic archive of β CMi to search for
evidence of the elusive companion. We detect periodic Doppler shifts
in the wings of the Hα line with a period of 170 days and an
amplitude of 2.25km/s, consistent with a low-mass binary companion
(M∼0.42M☉). We then compared small changes in the violet-to-red
peak height changes (V/R) with the orbital motion. We find weak
evidence that it does follow the orbital motion, as suggested by
recent Be binary models by Panoglou et al. Our results, which are
similar to those for several other Be stars, suggest that β CMi
may be a product of binary evolution where Roche lobe overflow has
spun up the current Be star, likely leaving a hot subdwarf or white
dwarf in orbit around the star. Unfortunately, no direct sign of this
companion star is found in the very limited archive of International
Ultraviolet Explorer spectra.
Description:
We collected 124 high-resolution spectra of β CMi between 2000
January 28 and 2016 May 6 with the 1.06m Ritter Observatory telescope
and a fiber fed echelle spectrograph (resolving power of R=26000;
∼4300-7000Å).
Objects:
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RA (ICRS) DE Designation(s) (Period)
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07 27 09.04 +08 17 21.5 β CMi = * bet CMi (P=170)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 32 124 Hα measurements
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See also:
III/254 : 2nd Cat. of RVs with Astrometric Data (Kharchenko+, 2007)
J/ApJS/161/118 : byHα photometry in open clusters (McSwain+, 2005)
J/ApJ/682/L117 : A spectroscopic orbit for Regulus (Gies+, 2008)
J/ApJ/686/1280 : Discovery of hot subdwarf companion to FY CMa (Peters+, 2008)
J/A+A/545/A121 : ο Puppis spectra (Koubsky+, 2012)
J/other/Sci/337.444 : RV curves of Galactic massive O stars (Sana+, 2012)
J/A+A/540/A53 : γ Cas radial velocity curve (Smith+, 2012)
J/ApJ/765/2 : FUV radial velocities of 59 Cyg (Peters+, 2013)
J/ApJ/828/47 : Radial velocities of the Be star HR 2142 (Peters+, 2016)
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 HJD Heliocentric Julian Date; JD-2450000
11- 15 F5.2 km/s RV [-5.5/9.4]? Differential radial velocities,
Hα line (1)
17- 20 F4.2 km/s e_RV [0.4/5]? Uncertainty in RV
22- 26 F5.3 --- V/R [0.9/1.1] Violet-to-red peak height changes (2)
28- 32 F5.3 --- e_V/R [0.006/0.05] Uncertainty in V/R
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Note (1): Differential radial velocities were measured with errors of
σ≲0.7km/s using the methods described in
Grundstrom (2007PhDT.........6G 2007PhDT.........6G), and had a range of ±5km/s.
Note (2): The V/R measurements were made by fitting two Gaussians to the
double-peaked emission, with no removal of the continuum. We did not
subtract the photospheric contribution from the V or R peak height in
the calculation of V/R. See section 4.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Sep-2017