THA 15-31: Discovery with VLT/X-shooter and Swift /UVOT of a new symbiotic star of the accreting-only variety
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Fecha
2022-05-01
Profesor/a Guía
Facultad/escuela
Idioma
en
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Editor
EDP Sciences
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Licencia CC
ATRIBUCIÓN 4.0 INTERNACIONAL
CC BY 4.0
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Licencia CC
https://creativecommons.org/licenses/by/4.0/deed.es
Resumen
We report the discovery and characterization of a new symbiotic star of the accreting-only variety, which we observed in the optical/near-infrared (NIR) with VLT/X-shooter and in the X-rays/ultraviolet with Swift/UVOT+XRT. The new symbiotic star, THA 15-31, was previously described as a pre-main sequence star belonging to the Lupus 3 association. Our observations, ancillary data, and Gaia EDR3 parallax indicate that THA 15-31 is a symbiotic star composed of an M6III red giant and an accreting companion, is subject to EB 0.38 reddening, and is located at a distance of 12 kpc and at 1.8 kpc above the Galactic plane in the outskirts of the Bulge. The luminosity of the accreting companion is 100, placing THA 15-31 among the symbiotic stars accreting at a high rate (2.5 10-8 yr-1 if the accretion is occurring on a white dwarf of 1M). The observed emission lines originate primarily from H I, He I, and Fe II, with no He II or other high-excitation lines observed; a sharp central absorption superimposed on the Balmer emission lines is observed, while all other lines have a simple Gaussian-like profile. The emission from the companion dominates over the M6III red giant at U and B-band wavelengths, and is consistent with an origin primarily in an optically thick accretion disk. No significant photometric variability is observed at optical or NIR wavelengths, suggesting either a face-on orbital orientation and/or that the red giant is far from Roche-lobe filling conditions. The profile of emission lines supports a low orbital inclination if they form primarily in the accretion disk. An excess emission is present in AllWISE W3 (12 μm) and W4 (22 μm) data, radiating a luminosity, consistent with thermal emission from optically thin circumstellar dust. © 2022 Authors
Notas
Indexación: Scopus.
Palabras clave
Binaries: symbiotic, Geometrical optics, Giant stars, Infrared devices, Iron compounds, Luminance, White dwarfs
Citación
Astronomy and Astrophysics, Volume 661, 1 May 2022, Article number A124
DOI
10.1051/0004-6361/202142058