TY - JOUR
T1 - Supersoft X-rays reveal a classical nova in the M 31 globular cluster Bol 126
AU - Henze, M.
AU - Pietsch, W.
AU - Haberl, F.
AU - Della Valle, M.
AU - Riffeser, A.
AU - Sala, G.
AU - Hatzidimitriou, D.
AU - Hofmann, F.
AU - Hartmann, D. H.
AU - Koppenhoefer, J.
AU - Seitz, S.
AU - Williams, G. G.
AU - Hornoch, K.
AU - Itagaki, K.
AU - Kabashima, F.
AU - Nishiyama, K.
AU - Xing, G.
AU - Lee, C. H.
AU - Magnier, E.
AU - Chambers, K.
N1 - Funding Information:
Partly based on observations with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and NASA.
Funding Information:
The anonymous referee is acknowledged for constructive comments that helped to improve the clarity of the paper. We would like to thank K. Lutz for her help in setting up the optical data reduction pipeline. The XMM-Newton project is supported by the Bundesministerium für Wirtschaft und Technologie/Deutsches Zentrum für Luft- und Raumfahrt (BMWI/DLR FKZ 50 OX 0001) and the Max Planck Society. We would like to thank the Swift team for the scheduling of the ToO observations. M. Henze acknowledges support from the BMWI/DLR, FKZ 50 OR 1010. The work of K. Hornoch was supported by the project RVO:67985815. We thank M. Wolf, P. Hornochová, P. Kušnirák, and P. Zasche for their assistance with acquiring of the observations at the Ondřejov Observatory. The PS1 Surveys have been made possible through contributions of the Institute for Astronomy at the University of Hawaii in Manoa, the Pan-STARRS Project Office, the Max Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, the Johns Hopkins University, the University of Durham, the University of Edinburgh, the Queens University of Belfast, the Harvard-Smithsonian Center for Astrophysics, and the Los Cumbres Observatory Global Telescope Network, Incorporated, and the National Central University of Taiwan.
PY - 2013/1
Y1 - 2013/1
N2 - Context. Classical novae (CNe) represent the main class of supersoft X-ray sources (SSSs) in the central region of our neighbouring galaxy M 31. Only three confirmed novae and three SSSs have been discovered in globular clusters (GCs) of any galaxy so far, of which one nova and two SSSs (including the nova) were found in M 31 GCs. Aims. To study the SSS state of CNe we carried out a high-cadence X-ray monitoring of the M 31 central area with XMM-Newton and Chandra. This project is supplemented by regular optical monitoring programmes at various observatories. Methods. We analysed X-ray and optical monitoring data of a new transient X-ray source in the M 31 GC Bol 126, discovered serendipitously in Swift observations. Our optical data set was based on regular M 31 monitoring programmes from five different small telescopes and was reduced using a homogeneous method. Additionally, we made use of Pan-STARRS 1 data obtained during the PAndromeda survey. We extracted light curves of the source in the optical and X-rays, as well as X-ray spectra. Results. Our observations reveal that the X-ray source in Bol 126 is the third SSS in an M 31 GC and can be confirmed as the second CN in the M 31 GC system. This nova is named M31N 2010-10f. Its properties in the X-ray (high black-body temperature, short SSS phase) and optical (relatively high maximum magnitude, fast decline) regimes agree with a massive white dwarf (MWD ≳ 1.3 M⊙) in the binary system. Incorporating the data on previously found (suspected) novae in M 31 GCs we used our high-cadence X-ray monitoring observations to estimate a tentative nova rate in the M 31 GC system of 0.05 yr-1 GC-1. An optical estimate, based on the recent 10.5-year WeCAPP survey, gives a lower nova rate, which is compatible with the X-ray rate on the 95% confidence level. Conclusions. Although still based on small-number statistics, there is growing evidence that the nova rate in GCs is higher than expected from primordial binary formation and under conditions as in the field. Dynamical binary formation and/or additional accretion from the intracluster medium are possible scenarios for an increased nova rate, but observational confirmation for this enhancement has been absent, so far. Regular X-ray monitoring observations of M 31 provide a promising strategy to find these novae.
AB - Context. Classical novae (CNe) represent the main class of supersoft X-ray sources (SSSs) in the central region of our neighbouring galaxy M 31. Only three confirmed novae and three SSSs have been discovered in globular clusters (GCs) of any galaxy so far, of which one nova and two SSSs (including the nova) were found in M 31 GCs. Aims. To study the SSS state of CNe we carried out a high-cadence X-ray monitoring of the M 31 central area with XMM-Newton and Chandra. This project is supplemented by regular optical monitoring programmes at various observatories. Methods. We analysed X-ray and optical monitoring data of a new transient X-ray source in the M 31 GC Bol 126, discovered serendipitously in Swift observations. Our optical data set was based on regular M 31 monitoring programmes from five different small telescopes and was reduced using a homogeneous method. Additionally, we made use of Pan-STARRS 1 data obtained during the PAndromeda survey. We extracted light curves of the source in the optical and X-rays, as well as X-ray spectra. Results. Our observations reveal that the X-ray source in Bol 126 is the third SSS in an M 31 GC and can be confirmed as the second CN in the M 31 GC system. This nova is named M31N 2010-10f. Its properties in the X-ray (high black-body temperature, short SSS phase) and optical (relatively high maximum magnitude, fast decline) regimes agree with a massive white dwarf (MWD ≳ 1.3 M⊙) in the binary system. Incorporating the data on previously found (suspected) novae in M 31 GCs we used our high-cadence X-ray monitoring observations to estimate a tentative nova rate in the M 31 GC system of 0.05 yr-1 GC-1. An optical estimate, based on the recent 10.5-year WeCAPP survey, gives a lower nova rate, which is compatible with the X-ray rate on the 95% confidence level. Conclusions. Although still based on small-number statistics, there is growing evidence that the nova rate in GCs is higher than expected from primordial binary formation and under conditions as in the field. Dynamical binary formation and/or additional accretion from the intracluster medium are possible scenarios for an increased nova rate, but observational confirmation for this enhancement has been absent, so far. Regular X-ray monitoring observations of M 31 provide a promising strategy to find these novae.
KW - Galaxies: individual: M 31
KW - Globular clusters: individual: Bol 126
KW - Novae cataclysmic variables
KW - Stars: individual: M31N 2010-10f
KW - X-rays: binaries
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U2 - 10.1051/0004-6361/201220196
DO - 10.1051/0004-6361/201220196
M3 - Article
AN - SCOPUS:84879663163
SN - 0004-6361
VL - 549
JO - Astronomy and astrophysics
JF - Astronomy and astrophysics
M1 - A120
ER -