The GALAH survey and symbiotic stars – I. Discovery and follow-up of 33 candidate accreting-only systems

Munari, U. and Traven, G. and Masetti, N. and Valisa, P. and Righetti, G. -L. and Hambsch, F. -J. and Frigo, A. and Cotar, K. and De Silva, G. M. and Freeman, K. C. and Lewis, G. F. and Martell, S. L. and Sharma, S. and Simpson, J. D. and Ting, Y. -S. and Wittenmyer, R. A. and Zucker, D. B. (2021) The GALAH survey and symbiotic stars – I. Discovery and follow-up of 33 candidate accreting-only systems. Monthly Notices of the Royal Astronomical Society, 505 (4). pp. 6121-6154. ISSN 0035-8711

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Abstract

We have identified a first group of 33 new candidates for symbiotic stars (SySt) of the accreting-only variety among the 600 255 stars so far observed by the GALactic Archaeology with HERMES (GALAH) high-resolution spectroscopic survey of the Southern hemisphere, more than doubling the number of those previously known. GALAH aims to high latitudes and this offers the possibility to sound the Galaxy for new SySt away from the usual plane and bulge hunting regions. In this paper, we focus on SySt of the M spectral type, showing an Hα emission with a peak in excess of 0.5 above the adjacent continuum level, and not affected by coherent radial pulsations. These constraints will be relaxed in future studies. The 33 new candidate SySt were subjected to an array of follow-up confirmatory observations [X-ray/ultraviolet (UV) observations with the Swift satellite, search for optical flickering, presence of a near-UV upturn in ground-based photometric and spectroscopic data, radial velocity changes suggestive of orbital motion, and variability of the emission-line profiles]. According to Gaia Early Data Release 3 (EDR3) parallaxes, the candidate new SySt are located at the tip of the giant branch, sharing the same distribution in M(Ks) of the well-established SySt. The accretion luminosities of the candidate new SySt are in the range 1-10 L⊙, corresponding to mass accretion rates of 0.1-1 × 10-9 M⊙ yr-1 for white dwarfs of 1 M⊙. The M giant of one of them presents a large lithium overabundance.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version deposited in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Date Deposited: 10 Jan 2022 00:20
Last Modified: 12 Jan 2022 03:29
Uncontrolled Keywords: methods: data analysis; binaries: symbiotic; X-rays: binaries; galaxies: stellar content; accretion; accretion discs; Astrophysics -; Solar and Stellar Astrophysics
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
Identification Number or DOI: https://doi.org/10.1093/mnras/stab1620
URI: http://eprints.usq.edu.au/id/eprint/45062

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