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The Mass Function of GX 339–4 from Spectroscopic Observations of Its Donor Star

Heida, M. and Jonker, P. G. and Torres, M. A. P. and Chiavassa, A. (2017) The Mass Function of GX 339–4 from Spectroscopic Observations of Its Donor Star. Astrophysical Journal, 846 (2). Art. No. 132. ISSN 1538-4357. doi:10.3847/1538-4357/aa85df.

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We obtained 16 VLT/X-shooter observations of GX 339−4 in quiescence during the period 2016 May–September and detected absorption lines from the donor star in its NIR spectrum. This allows us to measure the radial velocity curve and projected rotational velocity of the donor for the first time. We confirm the 1.76 day orbital period and we find that K_2 = 219 ± 3 km s^(−1), γ = 26 ± 2 km s^(−1), and v sin i = 64 ± 8 km s^(−1). From these values we compute a mass function f(M) = 1.91 ± 0.08 M_⊙, a factor ~3 lower than previously reported, and a mass ratio q = 0.18 ± 0.05. We confirm the donor is a K-type star and estimate that it contributes ~ 4% - 50% of the light in the J- and H-bands. We constrain the binary inclination to 37° < i < 78° and the black hole (BH) mass to 2.3 M_☉ < M_(BH) < 9.5 M_☉. GX 339−4 may therefore be the first BH to fall in the "mass-gap" of 2–5 M_⊙.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Heida, M.0000-0002-1082-7496
Jonker, P. G.0000-0001-5679-0695
Additional Information:© 2017 American Astronomical Society. Received 2017 May 23. Accepted 2017 August 9. Published 2017 September 11. M.H. would like to thank Javier García for valuable discussions. We would like to thank the ESO director for granting us DDT time for this project and the ESO staff for executing the observations. This research is based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program IDs 097.D-0915 and 297.D-5048. It also made use of data obtained from the ESO Science Archive Facility, program ID 085.B-0751. This research made use of the software package Molly provided by Tom Marsh. M.A.P.T. acknowledges support via a Ramon y Cajal Fellowship (RYC-2015-17854).
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Ramón y Cajal ProgrammeRYC-2015-17854
Subject Keywords:binaries: close; stars: individual (V821 Arae) ; X-rays: binaries
Issue or Number:2
Record Number:CaltechAUTHORS:20170911-140345285
Persistent URL:
Official Citation:M. Heida et al 2017 ApJ 846 132
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81304
Deposited On:11 Sep 2017 21:51
Last Modified:15 Nov 2021 19:42

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