The Library

Detection of the irradiated donor in the LMXBs 4U 1636-536 (=V801 Ara) and 4U 1735-444 (=V926 Sco)

Tools

Casares, J., Cornelisse, R., Steeghs, D., Charles, P. A., Hynes, R. I., O'Brien, K. and Strohmayer, T.. (2006) Detection of the irradiated donor in the LMXBs 4U 1636-536 (=V801 Ara) and 4U 1735-444 (=V926 Sco). Monthly Notices of the Royal Astronomical Society, Vol.373 (No.3). pp. 1235-1244. ISSN 0035-8711

Preview

Text
WRAP_Steeghs_LMXBs_0610086v1.pdf - Accepted Version
Download (705Kb) | Preview

Official URL: http://dx.doi.org/10.1111/j.1365-2966.2006.11106.x

Abstract

Phase-resolved VLT spectroscopy of the bursting low-mass X-ray binaries 4U 1636-536/V801 Ara and 4U 1735-444/V926 Sco is presented. Doppler images of the N iiiλ4640 Bowen transition reveal compact spots which we attribute to fluorescent emission from the donor star and enable us to define a new set of spectroscopic ephemerides. We measure Kem= 277 ± 22 and 226 ± 22 km s−1 from the N iii spots in V801 Ara and V926 Sco, respectively, which represent strict lower limits to the radial velocity semi-amplitude of the donor stars. Our new ephemerides provide confirmation that light-curve maxima in V801 Ara and likely V926 Sco occur at superior conjunction of the donor star and hence photometric modulation is caused by the visibility of the X-ray heated donor. The velocities of He iiλ4686 and the broad Bowen blend are strongly modulated with the orbital period, with phasing supporting emission dominated by the disc bulge. In addition, a reanalysis of burst oscillations in V801 Ara, using our spectroscopic T0, leads to K1= 90–113 km s−1. We also estimate the K-corrections for all possible disc flaring angles and present the first dynamical constraints on the masses of these X-ray bursters. These are K2= 360 ± 74 km s−1, f(M) = 0.76 ± 0.47 M⊙ and q= 0.21–0.34 for V801 Ara and K2= 298 ± 83 km s−1, f(M) = 0.53 ± 0.44 M⊙ and q= 0.05–0.41 for V926 Sco. Disc flaring angles α≥ 12° and q≃ 0.26–0.34 are favoured for V801 Ara whereas the lack of K1 constraint for V926 Sco prevents tight constraints on this system. Although both binaries seem to have intermediate inclinations, the larger equivalent width of the narrow N iii line in V801 Ara at phase 0.5 relative to phase 0 suggests that it has the higher inclination of the two.

Item Type:

Journal Article

Subjects:

Q Science > QB Astronomy

Divisions:

Faculty of Science > Physics

Library of Congress Subject Headings (LCSH):

X-ray binaries

Journal or Publication Title:

Monthly Notices of the Royal Astronomical Society

Publisher:

Wiley

ISSN:

0035-8711

Official Date:

2006

Dates:

Date	Event
2006	Published

Volume:

Vol.373

Number:

No.3

Page Range:

pp. 1235-1244

Identification Number:

10.1111/j.1365-2966.2006.11106.x

Status:

Peer Reviewed

Publication Status:

Published

Access rights to Published version:

Restricted or Subscription Access

Funder:

Spain. Ministerio de Ciencia e Innovación (MICINN), Smithsonian Astrophysical Observatory, United States. National Aeronautics and Space Administration (NASA)

Grant number:

AYA2002-03570 (MICINN), NNG04GG96G (NASA), NNG04G014G (NASA)

References:

van Amerongen S., Pedersen H., van Paradijs J., 1987, A&A, 185,
147
Augusteijn T., van der Hooft F., de Jong J.A.., van KerkwijkM.H.,
van Paradijs J., 1998, A&A, 332, 561 (A98)
Casares J., Steeghs D., Hynes R.I., Charles P.A., O’Brien K.,
2003, ApJ, 590, 1041
Corbet R.H.D., Thorstensen J.R., Charles P.A., Menzies J.W.,
Naylor T., Smale A.P., 1986, MNRAS, 222, 15P
Cornelisse R., Steeghs D., Casares J., Barnes A.D., Charles P.A.,
Hynes R.I., O’Brien K., 2006, MNRAS, submitted
Cowley A.P., Crampton D., Hutchings J.B., 1882, ApJ, 255, 596
Frank, J., King A.R., Lasota J.-P., 1987, A&A, 178, 137
Galloway D.K., Psaltis D., Muno M.P., Chakrabarty D., 2005,
ApJ, in press, astro-ph/05113801
Giles A.B., Hill K.M., Strohmayer T.E., Cumming N., 2002, ApJ,
568, 279 (G02)
Gray D.F., 1992, “The observation and Analysis of Stellar Photospheres”,
CUP 20
Hasinger G., van der Klis M., 1989, A&A, 225, 79
Haswell C.A., King A.R., Murray J.R., Charles P.A., 2001, MNRAS,
321, 475
Hellier C., Mason K.O., 1989, MNRAS, 239, 715
Horne K., 1986, PASP, 98, 609
Hynes R.I., Steeghs D., Casares J., Charles P. A., O’Brien K.,
2003, ApJ, 583, L95
de Jong J.A., van Paradijs J., Augusteijn T., 1996, A&A, 314, 484
Marsh T.R., 1998, inWild Stars in the OldWest, eds. S. Howell, E.
Kuulkerss and C. Woodward (ASP Conf. Series) vol. 137, p.236
Marsh T.R., 2001, in Astrotomography, Indirect Imaging Methods
in Observational Astronomy, eds. H.M.J. Boffin, D. Steeghs and
J. Cuypers (Lecture Notes in Physics) vol. 573, p.1
Meyer F., Meyer-Hofmeister E., 1982, A&A, 106, 34
McClintock J.E., Canizares C., Tarter C.B., 1975, ApJ, 198, 641
Mu˜noz-Darias T., Casares J., Mart´ınez-Pais, I.G., 2005, ApJ, 635,
502
Nakanishi H., Sofue Y., 2003, PASJ, 55, 191
Nussbaumer H., 1971, ApJ, 170, 93
Paczynski B., 1971, Ann. Rev. A&A, 9, 183
van Paradijs J., van der KlisM., Pedersen H., 1988, A&A, 76, 185
van Paradijs J. et al., 1990, A&A, 234, 181
van Paradijs J., McClintock J. E., 1995, in X-ray Binaries,
Cambridge Astrophysics Series: Cambridge University
Press. eds. W.H.G. Lewin, J. van Paradijs & E.P.J. van den
Heuvel, p. 58
Pedersen H., van Paradijs J., Lewin W.H.G., 1981, Nature, 294,
725
Rhoades C.E., Ruffini R., 1974, Phys. Rev. Lett., 32, 324
Shafter A.W., Szkody P., Thorstensen J.R., 1986, ApJ, 308, 765
Schachter J., Filippenko A.V., Kahn S.M., 1989, ApJ, 340, 1049
Schenker K., King A.R., 2002, ASP Conf. Ser. 261: The Physics
of Cataclysmic Variables and Related Objects, 261, 242
Schneider D.P., Young P., 1980, ApJ, 238, 946
Smith D.A., Dhillon V.S., 1998, MNRAS, 301, 767
Steeghs D., Casares J., 2002, ApJ, 568, 273 (SC02)
Strohmayer T.E., Zhang W., Swank J.H., White N.E., Lapidus I.,
1998, ApJ, 498, L135
Strohmayer T.E., Markwardt C.B., 2002, ApJ, 577, 337 (SM02)
Strohmayer T.E., Bildsten L., 2004, in X-ray Binaries, Cambridge
Astrophysics Series: Cambridge University Press. 2004. eds.
W.H.G. Lewin & M. van der Klis.
Smale A.P., Corbet R.H.D., 1991, ApJ, 383, 853
Tout C.A., Pols O.R., Eggleton P.P., Zhanwen H., 1996, MNRAS,
281, 257
Wade R.A., Horne, K., 1988, ApJ, 324, 411
Warner B., 1995, ApJ&SS, 232, 89