CXO J004318.8+412016*A steady supersoft X-ray source in M 31
We obtained an optical spectrum of a star we identify as the optical counterpart of the M31 Chandra source CXO J004318.8+412016, because of prominent emission lines of the Balmer series, of neutral helium, and a He II line at 4686 Å. The continuum energy distribution and the spectral characteristics...
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todo:paper_00358711_v470_n2_p2212_Orio2023-10-03T14:47:20Z CXO J004318.8+412016*A steady supersoft X-ray source in M 31 Orio, M. Luna, G.J.M. Kotulla, R. Gallager, J.S. Zampieri, L. Mikolajewska, J. Harbeck, D. Bianchini, A. Chiosi, E. Della Valle, M. de Martino, D. Kaur, A. Mapelli, M. Munari, U. Odendaal, A. Trinchieri, G. Wade, J. Zemko, P. Binaries: symbiotic Galaxies: individual: M31 White dwarfs X-rays: binaries X-rays: individual: CXO J004318.8+412016 We obtained an optical spectrum of a star we identify as the optical counterpart of the M31 Chandra source CXO J004318.8+412016, because of prominent emission lines of the Balmer series, of neutral helium, and a He II line at 4686 Å. The continuum energy distribution and the spectral characteristics demonstrate the presence of a red giant of K or earlier spectral type, so we concluded that the binary is likely to be a symbiotic system. CXO J004318.8+412016 has been observed in X-rays as a luminous supersoft source (SSS) since 1979, with effective temperature exceeding 40 eV and variable X-ray luminosity, oscillating between a few times 1035 erg s-1 and a few times 1037 erg s-1 in the space of a few weeks. The optical, infrared and ultraviolet colours of the optical object are consistent with an an accretion disc around a compact object companion, which may be either a white dwarf or a black hole, depending on the system parameters. If the origin of the luminous supersoft X-rays is the atmosphere of a white dwarf that is burning hydrogen in shell, it is as hot and luminous as post-thermonuclear flash novae, yet no major optical outburst has ever been observed, suggesting that the white dwarf is very massive (m ≥ 1.2 M⊙) and it is accreting and burning at the high rate m > 10-8 M⊙ yr-1 expected for Type Ia supernovae progenitors. In this case, the X-ray variability may be due to a very short recurrence time of only mildly degenerate thermonuclear flashes. © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Fil:Luna, G.J.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00358711_v470_n2_p2212_Orio |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Binaries: symbiotic Galaxies: individual: M31 White dwarfs X-rays: binaries X-rays: individual: CXO J004318.8+412016 |
| spellingShingle |
Binaries: symbiotic Galaxies: individual: M31 White dwarfs X-rays: binaries X-rays: individual: CXO J004318.8+412016 Orio, M. Luna, G.J.M. Kotulla, R. Gallager, J.S. Zampieri, L. Mikolajewska, J. Harbeck, D. Bianchini, A. Chiosi, E. Della Valle, M. de Martino, D. Kaur, A. Mapelli, M. Munari, U. Odendaal, A. Trinchieri, G. Wade, J. Zemko, P. CXO J004318.8+412016*A steady supersoft X-ray source in M 31 |
| topic_facet |
Binaries: symbiotic Galaxies: individual: M31 White dwarfs X-rays: binaries X-rays: individual: CXO J004318.8+412016 |
| description |
We obtained an optical spectrum of a star we identify as the optical counterpart of the M31 Chandra source CXO J004318.8+412016, because of prominent emission lines of the Balmer series, of neutral helium, and a He II line at 4686 Å. The continuum energy distribution and the spectral characteristics demonstrate the presence of a red giant of K or earlier spectral type, so we concluded that the binary is likely to be a symbiotic system. CXO J004318.8+412016 has been observed in X-rays as a luminous supersoft source (SSS) since 1979, with effective temperature exceeding 40 eV and variable X-ray luminosity, oscillating between a few times 1035 erg s-1 and a few times 1037 erg s-1 in the space of a few weeks. The optical, infrared and ultraviolet colours of the optical object are consistent with an an accretion disc around a compact object companion, which may be either a white dwarf or a black hole, depending on the system parameters. If the origin of the luminous supersoft X-rays is the atmosphere of a white dwarf that is burning hydrogen in shell, it is as hot and luminous as post-thermonuclear flash novae, yet no major optical outburst has ever been observed, suggesting that the white dwarf is very massive (m ≥ 1.2 M⊙) and it is accreting and burning at the high rate m > 10-8 M⊙ yr-1 expected for Type Ia supernovae progenitors. In this case, the X-ray variability may be due to a very short recurrence time of only mildly degenerate thermonuclear flashes. © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. |
| format |
JOUR |
| author |
Orio, M. Luna, G.J.M. Kotulla, R. Gallager, J.S. Zampieri, L. Mikolajewska, J. Harbeck, D. Bianchini, A. Chiosi, E. Della Valle, M. de Martino, D. Kaur, A. Mapelli, M. Munari, U. Odendaal, A. Trinchieri, G. Wade, J. Zemko, P. |
| author_facet |
Orio, M. Luna, G.J.M. Kotulla, R. Gallager, J.S. Zampieri, L. Mikolajewska, J. Harbeck, D. Bianchini, A. Chiosi, E. Della Valle, M. de Martino, D. Kaur, A. Mapelli, M. Munari, U. Odendaal, A. Trinchieri, G. Wade, J. Zemko, P. |
| author_sort |
Orio, M. |
| title |
CXO J004318.8+412016*A steady supersoft X-ray source in M 31 |
| title_short |
CXO J004318.8+412016*A steady supersoft X-ray source in M 31 |
| title_full |
CXO J004318.8+412016*A steady supersoft X-ray source in M 31 |
| title_fullStr |
CXO J004318.8+412016*A steady supersoft X-ray source in M 31 |
| title_full_unstemmed |
CXO J004318.8+412016*A steady supersoft X-ray source in M 31 |
| title_sort |
cxo j004318.8+412016*a steady supersoft x-ray source in m 31 |
| url |
http://hdl.handle.net/20.500.12110/paper_00358711_v470_n2_p2212_Orio |
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