SIMBAD references

2021A&A...646A.119P - Astronomy and Astrophysics, volume 646A, 119-119 (2021/2-1)

Forbidden hugs in pandemic times. I. Luminous red nova AT 2019zhd, a new merger in M 31.

PASTORELLO A., FRASER M., VALERIN G., REGUITTI A., ITAGAKI K., OCHNER P., WILLIAMS S.C., JONES D., MUNDAY J., SMARTT S.J., SMITH K.W., SRIVASTAV S., ELIAS-ROSA N., KANKARE E., KARAMEHMETOGLU E., LUNDQVIST P., MAZZALI P.A., MUNARI U., STRITZINGER M.D., TOMASELLA L., ANDERSON J.P., CHAMBERS K.C. and REST A.

Abstract (from CDS):

We present the follow-up campaign of the luminous red nova (LRN) AT 2019zhd, the third event of this class observed in M 31. The object was followed by several sky surveys for about five months before the outburst, during which it showed a slow luminosity rise. In this phase, the absolute magnitude ranged from Mr=-2.8±0.2mag to Mr=-5.6±0.1mag. Then, over a four to five day period, AT 2019zhd experienced a major brightening, reaching a peak of Mr=-9.61±0.08mag and an optical luminosity of 1.4 x 1039 erg s–1. After a fast decline, the light curve settled onto a short-duration plateau in the red bands. Although less pronounced, this feature is reminiscent of the second red maximum observed in other LRNe. This phase was followed by a rapid linear decline in all bands. At maximum, the spectra show a blue continuum with prominent Balmer emission lines. The post-maximum spectra show a much redder continuum, resembling that of an intermediate-type star. In this phase, Hα becomes very weak, Hβ is no longer detectable, and a forest of narrow absorption metal lines now dominate the spectrum. The latest spectra, obtained during the post-plateau decline, show a very red continuum (Teff≃3000K) with broad molecular bands of TiO, similar to those of M-type stars. The long-lasting, slow photometric rise observed before the peak resembles that of LRN V1309 Sco, which was interpreted as the signature of the common-envelope ejection. The subsequent outburst is likely due to the gas outflow following a stellar merging event. The inspection of archival HST images taken 22 years before the LRN discovery reveals a faint red source (MF555W=0.21±0.14mag, with F555W-F814W=2.96±0.12mag) at the position of AT 2019zhd, which is the most likely quiescent precursor. The source is consistent with expectations for a binary system including a predominant M5-type star.

Abstract Copyright: © ESO 2021

Journal keyword(s): binaries: close - stars: winds - outflows - stars: individual: AT 2019zhd - stars: individual: M31-LRN2015 - stars: individual: NAME M31 RV{M31-RV} - stars: individual: V838 Mon

VizieR on-line data: <Available at CDS (J/A+A/646/A119): table1.dat table2.dat>

Simbad objects: 16

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2021.12.04-02:04:43

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