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Spectroscopic evidence for a 5.4 minute orbital period in HM Cancri

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Roelofs, Gijs H. A., Rau, Arne, Marsh, T. R., Steeghs, D., Groot, P. J. and Nelemans, G.. (2010) Spectroscopic evidence for a 5.4 minute orbital period in HM Cancri. Astrophysical Journal Letters, Vol.711 (No.2). L138-L142. ISSN 2041-8205

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Official URL: http://dx.doi.org/10.1088/2041-8205/711/2/L138

Abstract

HM Cancri is a candidate ultracompact binary white dwarf with an apparent orbital period of only 5.4 minutes, as suggested by X-ray and optical light-curve modulations on that period, and by the absence of longer-period variability. In this Letter, we present Keck-I spectroscopy which shows clear modulation of the helium emission lines in both radial velocity and amplitude on the 5.4 minute period and no other. The data strongly suggest that the binary is emitting He I 4471 from the irradiated face of the cooler, less massive star, and He II 4686 from a ring around the more massive star. From their relative radial velocities, we measure a mass ratio q = 0.50 +/- 0.13. We conclude that the observed 5.4 minute period almost certainly represents the orbital period of an interacting binary white dwarf. We thus confirm that HM Cnc is the shortest period binary star known: a unique test for stellar evolution theory, and one of the strongest known sources of gravitational waves for LISA.

Item Type:

Journal Article

Subjects:

Q Science > QB Astronomy

Divisions:

Faculty of Science > Physics

Library of Congress Subject Headings (LCSH):

Double stars, White dwarf stars

Journal or Publication Title:

Astrophysical Journal Letters

Publisher:

IOP Publishing Ltd

ISSN:

2041-8205

Official Date:

10 March 2010

Dates:

Date	Event
10 March 2010	Published

Volume:

Vol.711

Number:

No.2

Number of Pages:

Page Range:

L138-L142

Identification Number:

10.1088/2041-8205/711/2/L138

Status:

Peer Reviewed

Publication Status:

Published

Access rights to Published version:

Restricted or Subscription Access

Funder:

United States. National Aeronautics and Space Administration (NASA), W. M. Keck Foundation, Nederlandse Organisatie voor Wetenschappelijk Onderzoek [Netherlands Organisation for Scientific Research] (NWO)

Grant number:

680.50.0610 (NWO), NNX08AK66G (NASA)

Related URLs:

Other Repository

References:

Barros, S. C. C., Marsh, T. R., Groot, P., Nelemans, G., Ramsay,
G., Roelofs, G., Steeghs, D., Wilms, J. 2005, MNRAS, 357,
1306
Barros, S. C. C. et al. 2007, MNRAS, 374, 1334
Cropper, M., Harrop-Allin, M. K., Mason, K. O., Mittaz, J. P.
D., Potter, S. B., Ramsay, G. 1998, MNRAS, 293, L57
Dall'Osso, S., Israel, G.L., & Stella, L. 2006, A&A, 447, 785
Dall'Osso, S., Israel, G.L., & Stella, L. 2007, A&A, 464, 417
D'Antona, F., Ventura, P., Burderi, L, & Teodorescu, A. 2006,
ApJ, 653, 1429
Deloye, C. J., & Taam, R. E. 2006, ApJ, 649, L99
Deloye, C. J., Taam, R. E., Winisdoerfler, C., Chabrier, G. 2007,
MNRAS, 381, 525
Hakala, P., Ramsay, G., Wu, K., Hjalmarsdotter, L., Jarvinen, S.,
Jarvinen, A., Cropper, M. 2003, MNRAS, 343, L10
Hakala, P., Ramsay, G., & Byckling, K. 2004, MNRAS, 353, 453
Israel, G.L. et al. 2002, A&A, 386, L13
Israel, G.L. et al. 2004, Mem. Soc. Astron. Ital. Suppl., 5, 148
Marsh, T. R., & Horne, K. 1988, MNRAS, 235, 269
Marsh, T. R., & Steeghs, D. 2002, MNRAS, 331, L7
Mu~noz-Darias, T., Casares, J., & Martinez-Pais, I.G. 2005, ApJ,
635, 502
Motch, C., Haberl, F., Guillout, P., Pakull, M., Reinsch, K., &
Krautter, J. 1996, A&A, 307, 459
Nelemans, G., Portegies Zwart, S.F., Verbunt, F., & Yungelson,
L.R. 2001, A&A, 368, 939
Nelemans, G. 2009, Class. Quantum Gravity, 26, 094030
Norton, A.J., Haswell, C.A., & Wynn, G.A. 2004, A&A, 419, 1025
Oke, J.B. et al. 1995, PASP, 107, 375
Ramsay, G., Cropper, M., Wu, K., Mason, K.O., Hakala, P. 2000,
MNRAS, 311, 75
Ramsay, G., Hakala, P., & Cropper, M. 2002a, MNRAS, 332, L7
Ramsay, G., Wu, K., Cropper, M., Schmidt, G., Sekiguchi, K.,
Iwamuro, F., Maihara, T. 2002b, MNRAS, 333, 575
Reinsch, K., Steiper, J., & Dreizler, S. 2007, in ASP Conf. Ser.
372, Spectral Analysis and Constraints on the Nature of the
Ultra-Compact Binary RX J0806.3+1527, ed. R. Napiwotzki &
M.R. Burleigh (San Francisco, CA: ASP), 419
Roelofs, G.H.A. et al. 2009, MNRAS, 394, 367
Steeghs, D., Marsh, T. R., Barros, S. C. C., Nelemans, G., Groot,
P. J., Roelofs, G. H. A., Ramsay, G., Cropper, M. 2006, ApJ,
649, 382
Strohmayer, T.E. 2002, ApJ, 581, 577
Strohmayer, T.E. 2003, ApJ, 593, L39
Strohmayer, T.E. 2004, ApJ, 610, 416
Strohmayer, T.E. 2005, ApJ, 627, 920
Strohmayer, T.E. 2008, ApJ, 679, L109
van der Sluys, M. V., Verbunt, F., & Pols, O. R. 2005, A&A, 440,
973
Wood, M.A. 2009, MNRAS, 395, 378
Wu, K., Cropper, M., Ramsay, G., Sekiguchi, K. 2002, MNRAS,
331, 221
Yungelson, L.R. 2008, Astron. Lett., 34, 620