Discovery of a red supergiant donor star in SN2010da/NGC 300 ULX-1
| Autor: | Frank Tramper, Fiona A. Harrison, Ben Davies, Brian W. Grefenstette, J. A. Kennea, Dominic J. Walton, Marianne Heida, M. Brightman, Ryan M. Lau, Felix Fürst |
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| Rok vydání: | 2019 |
| Předmět: |
010504 meteorology & atmospheric sciences
FOS: Physical sciences Astrophysics Astronomy & Astrophysics MASS 01 natural sciences 0103 physical sciences Red supergiant ACCRETION 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) 0105 earth and related environmental sciences Physics PULSATIONS High Energy Astrophysical Phenomena (astro-ph.HE) Spectral index Science & Technology SPECTROSCOPY COUNTERPART Neutron stars (1108) Stellar atmosphere Astronomy and Astrophysics PULSAR Mass ratio Orbital period High mass X-ray binary stars (733) Astrophysics - Astrophysics of Galaxies EVOLUTION GALAXY Radial velocity Neutron star Supernova impostor Late-type supergiant stars (910) Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Physical Sciences BLACK-HOLE Astrophysics - High Energy Astrophysical Phenomena X-RAY SOURCE |
| DOI: | 10.48550/arxiv.1909.02171 |
| Popis: | SN2010da/NGC 300 ULX-1 was first detected as a supernova impostor in May 2010 and was recently discovered to be a pulsating ultraluminous X-ray source. In this letter, we present VLT/X-shooter spectra of this source obtained in October 2018, covering the wavelength range 350-2300 nm. The $J$- and $H$-bands clearly show the presence of a red supergiant donor star that is best matched by a MARCS stellar atmosphere with $T_{\rm eff} = 3650 - 3900$ K and $\log(L_{\rm bol}/L_{\odot}) = 4.25\pm0.10$, which yields a stellar radius $R = 310 \pm 70 R_{\odot}$. To fit the full spectrum, two additional components are required: a blue excess that can be fitted either by a hot blackbody (T $\gtrsim 20,000$ K) or a power law (spectral index $\alpha \approx 4$) and is likely due to X-ray emission reprocessed in the outer accretion disk or the donor star; and a red excess that is well fitted by a blackbody with a temperature of $\sim 1100$ K, and is likely due to warm dust in the vicinity of SN2010da. The presence of a red supergiant in this system implies an orbital period of at least 0.8-2.1 years, assuming Roche lobe overflow. Given the large donor-to-compact object mass ratio, orbital modulations of the radial velocity of the red supergiant are likely undetectable. However, the radial velocity amplitude of the neutron star is large enough (up to 40-60 km s$^{-1}$) to potentially be measured in the future, unless the system is viewed at a very unfavorable inclination. Comment: 10 pages, 6 figures, accepted for publication in ApJ Letters |
| Databáze: | OpenAIRE |
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