J/ApJ/913/48 Average BVR light curve & RV of HD96670 (Gomez+, 2021)
Optical analysis and modeling of HD96670, a new black hole X-ray binary
candidate.
Gomez S., Grindlay J.E.
<Astrophys. J., 913, 48 (2021)>
=2021ApJ...913...48G 2021ApJ...913...48G
ADC_Keywords: Binaries, X-ray; Photometry; Optical; Radial velocities
Keywords: High mass x-ray binary stars ; X-ray binary stars
Abstract:
We report on optical observations and modeling of HD96670, a
single-line spectroscopic binary in the Carina OB2 association. We
collected 10 epochs of optical spectroscopy, and optical photometry on
17 nonconsecutive nights on the source. We construct a radial velocity
curve from the spectra, and update the orbital period of the binary to
be P=5.28388±0.00046days. The spectra show oxygen and helium
absorption, consistent with an O-type primary. We see no evidence for
spectral lines from the secondary star in the binary. We model the
optical light curve and radial velocity curve simultaneously using the
Wilson-Devinney code and find a best-fit mass of
M1=22.7-3.6+5.2M☉ for the primary, and
M2=6.2-0.7+0.9M☉ for the secondary. An object of this mass
is consistent with either a B-type star, or a black hole. Given that
we see no absorption lines from the secondary, in combination with an
observed hard power-law X-ray spectrum with Γ=2.6 detected past
10keV that may have been produced by wind accretion onto the
secondary, we conclude that the secondary is most likely a black hole.
We see asymmetrical helium lines with a shape consistent with the
presence of a third star. If the secondary is indeed a black hole,
this system would add to the small sample of only four possible black
hole high mass X-ray binaries in the galaxy.
Description:
We requested optical photometry from the American Association of
Variable Star Observers (AAVSO), and observed HD96670 in the B, V, and
R bands between 2015 June and 2015 July with the Berry 6cm bright star
monitor telescope, located in Perth, Australia. We obtained additional
photometry with the SMARTS CTIO 1.3m Telescope using ANDICAM also in
the B, V, and R bands between 2016 March and April.
We collected optical spectroscopy with the CHIRON echelle spectrograph
on the CTIO 1.5m SMARTS telescope between 2016 April and May, and the
Inamori-Magellan Areal Camera and Spectrograph (IMACS) spectrograph on
the Magellan Baade Telescope at Las Campanas Observatory, and the MagE
echellette spectrograph on the same telescope between 2017 January and
February.
HD96670 was first detected in the X-rays by the XMM-Newton slew survey
on 2010 July 23. Subsequent observations by NuSTAR on 2015 March 4,
29, and April 29 revealed an X-ray spectrum with a hard power-law
component. See Section 2.4.
Objects:
----------------------------------------------------------------
RA (ICRS) DE Designation(s) (Period)
----------------------------------------------------------------
11 07 13.93 -59 52 23.1 HD96670 = TYC 8628-3-1 (P=5.2838)
----------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
fig5a.dat 30 3443 Phased V, B, R light curve
fig5b.dat 29 50 Radial velocity curve
--------------------------------------------------------------------------------
See also:
II/328 : AllWISE Data Release (Cutri+ 2013)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/A+A/407/1039 : X-ray power spectra of Cygnus X-1 (Pottschmidt+, 2003)
J/ApJ/681/562 : Orbits of 5 Cet and AX Mon (Eaton, 2008)
J/A+A/480/611 : XMM-Newton slew survey catalogue, XMMSL1 (Saxton+, 2008)
J/AN/331/349 : O, B & red supergiant masses & luminosities (Hohle+, 2010)
J/ApJS/194/7 : X-ray properties of O and B stars in Carina (Naze+, 2011)
J/ApJS/215/15 : SMaSH+: observations and companion detection (Sana+, 2014)
J/A+A/613/A9 : Extinction towards Galactic O stars (Maiz Apellaniz+, 2018)
Byte-by-byte Description of file: fig5a.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 F16.8 d HJD Heliocentric Julian Date
18- 23 F6.4 mag mag [7.47/7.76] Average V, B, R magnitude
25- 30 F6.4 mag e_mag [0.002/0.09] Uncertainty in mag
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig5b.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 F16.8 d HJD Heliocentric Julian Date
18- 24 F7.3 km/s RVel [-86/33] Radial velocity
26- 29 F4.2 km/s e_RVel [0.7/7] Uncertainty in RVel
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 25-Nov-2022