Discovery of the first symbiotic star in NGC 6822

Alexei Y. Kniazev; Petri Väisänen; Patricia A. Whitelock; John W. Menzies; Michael W. Feast; Eva K. Grebel; David A.H. Buckley; Yas Hashimoto; Nicola Loaring; Encarni Romero-Colmenero; Ramotholo Sefako; Eric B. Burgh; Kenneth Nordsieck

doi:10.1111/j.1365-2966.2009.14617.x

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Abstract

We report the discovery of the first symbiotic star (V = 21.6, K _S = 15.8 mag) in the Local Group dwarf irregular galaxy NGC 6822. This star was identified during a spectral survey of Hα emission-line objects using the Southern African Large Telescope during its performance-verification phase. The observed strong emission lines of H i and He ii suggest a high electron density and T* < 130 000 K for the hot companion. The infrared colours allow us to classify this object as an S-type symbiotic star, comprising a red giant losing mass to a compact companion. The red giant is an asymptotic giant branch (AGB) carbon star, and a semiregular variable, pulsating in the first overtone with a period of 142 d. Its bolometric magnitude is M_bol = -4.4 mag. We review what is known about the luminosities of extragalactic symbiotic stars, showing that most, possibly all, contain AGB stars. We suggest that a much larger fraction of Galactic symbiotic stars may contain AGB stars than was previously realized.

Original language	English
Pages (from-to)	1121-1126
Number of pages	6
Journal	Monthly Notices of the Royal Astronomical Society
Volume	395
Issue number	2
DOIs	https://doi.org/10.1111/j.1365-2966.2009.14617.x
Publication status	Published - 2009 May
Externally published	Yes

Keywords

Binaries: symbiotic
Galaxies: individual: NGC 6822
Stars: mass-loss

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1111/j.1365-2966.2009.14617.x

Cite this

Kniazev, A. Y., Väisänen, P., Whitelock, P. A., Menzies, J. W., Feast, M. W., Grebel, E. K., Buckley, D. A. H., Hashimoto, Y., Loaring, N., Romero-Colmenero, E., Sefako, R., Burgh, E. B., & Nordsieck, K. (2009). Discovery of the first symbiotic star in NGC 6822. Monthly Notices of the Royal Astronomical Society, 395(2), 1121-1126. https://doi.org/10.1111/j.1365-2966.2009.14617.x

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abstract = "We report the discovery of the first symbiotic star (V = 21.6, K S = 15.8 mag) in the Local Group dwarf irregular galaxy NGC 6822. This star was identified during a spectral survey of Hα emission-line objects using the Southern African Large Telescope during its performance-verification phase. The observed strong emission lines of H i and He ii suggest a high electron density and T* < 130 000 K for the hot companion. The infrared colours allow us to classify this object as an S-type symbiotic star, comprising a red giant losing mass to a compact companion. The red giant is an asymptotic giant branch (AGB) carbon star, and a semiregular variable, pulsating in the first overtone with a period of 142 d. Its bolometric magnitude is Mbol = -4.4 mag. We review what is known about the luminosities of extragalactic symbiotic stars, showing that most, possibly all, contain AGB stars. We suggest that a much larger fraction of Galactic symbiotic stars may contain AGB stars than was previously realized.",

keywords = "Binaries: symbiotic, Galaxies: individual: NGC 6822, Stars: mass-loss",

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doi = "10.1111/j.1365-2966.2009.14617.x",

language = "English",

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AU - Kniazev, Alexei Y.

AU - Väisänen, Petri

AU - Whitelock, Patricia A.

AU - Menzies, John W.

AU - Feast, Michael W.

AU - Grebel, Eva K.

AU - Buckley, David A.H.

AU - Hashimoto, Yas

AU - Loaring, Nicola

AU - Romero-Colmenero, Encarni

AU - Sefako, Ramotholo

AU - Burgh, Eric B.

AU - Nordsieck, Kenneth

PY - 2009/5

Y1 - 2009/5

N2 - We report the discovery of the first symbiotic star (V = 21.6, K S = 15.8 mag) in the Local Group dwarf irregular galaxy NGC 6822. This star was identified during a spectral survey of Hα emission-line objects using the Southern African Large Telescope during its performance-verification phase. The observed strong emission lines of H i and He ii suggest a high electron density and T* < 130 000 K for the hot companion. The infrared colours allow us to classify this object as an S-type symbiotic star, comprising a red giant losing mass to a compact companion. The red giant is an asymptotic giant branch (AGB) carbon star, and a semiregular variable, pulsating in the first overtone with a period of 142 d. Its bolometric magnitude is Mbol = -4.4 mag. We review what is known about the luminosities of extragalactic symbiotic stars, showing that most, possibly all, contain AGB stars. We suggest that a much larger fraction of Galactic symbiotic stars may contain AGB stars than was previously realized.

AB - We report the discovery of the first symbiotic star (V = 21.6, K S = 15.8 mag) in the Local Group dwarf irregular galaxy NGC 6822. This star was identified during a spectral survey of Hα emission-line objects using the Southern African Large Telescope during its performance-verification phase. The observed strong emission lines of H i and He ii suggest a high electron density and T* < 130 000 K for the hot companion. The infrared colours allow us to classify this object as an S-type symbiotic star, comprising a red giant losing mass to a compact companion. The red giant is an asymptotic giant branch (AGB) carbon star, and a semiregular variable, pulsating in the first overtone with a period of 142 d. Its bolometric magnitude is Mbol = -4.4 mag. We review what is known about the luminosities of extragalactic symbiotic stars, showing that most, possibly all, contain AGB stars. We suggest that a much larger fraction of Galactic symbiotic stars may contain AGB stars than was previously realized.

KW - Binaries: symbiotic

KW - Galaxies: individual: NGC 6822

KW - Stars: mass-loss

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