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Forbidden hugs in pandemic times: I. Luminous red nova at 2019zhd, a new merger in M 31
- Source :
- Digital.CSIC. Repositorio Institucional del CSIC, instname, 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 & Rest, A 2021, ' Forbidden hugs in pandemic times : I. Luminous red nova AT 2019zhd, a new merger in M 31 ', Astronomy and Astrophysics, vol. 646, A119 . https://doi.org/10.1051/0004-6361/202039952
- Publication Year :
- 2021
- Publisher :
- EDP Sciences, 2021.
-
Abstract
- 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 ± 0.2 mag to Mr =-5.6 ± 0.1 mag. Then, over a four to five day period, AT 2019zhd experienced a major brightening, reaching a peak of Mr =-9.61 ± 0.08 mag and an optical luminosity of 1.4 × 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 ≈ 3000 K) 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 ± 0.14 mag, with F555W-F814W = 2.96 ± 0.12 mag) 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.
- Subjects :
- individuals: V838 Mon [Stars]
V838 MON
TRANSFORMATIONS
Outflows
Astrophysics
individual: M32-LRN2015 [Stars]
01 natural sciences
Stars: individual: AT 2019zhd
individual: AT 2019zhd [Stars]
Binaries: close
0103 physical sciences
Pandemic
individual: M31-RV [Stars]
PHOTOMETRY
OUTBURST
winds, outflows [stars]
winds [Stars]
010303 astronomy & astrophysics
Physics
SPECTROSCOPY
STELLAR MERGERS
010308 nuclear & particles physics
Astronomy and Astrophysics
Stars: winds
EVOLUTION
individual: M31-LRN2015 [stars]
individual: V838 Mon [stars]
13. Climate action
Space and Planetary Science
Stars: individuals: V838 Mon
Stars: individual: M32-LRN2015
Luminous red nova
SN HUNT 248
close [Binaries]
Stars: individual: M31-RV
Subjects
Details
- Database :
- OpenAIRE
- Journal :
- Digital.CSIC. Repositorio Institucional del CSIC, instname, 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 & Rest, A 2021, ' Forbidden hugs in pandemic times : I. Luminous red nova AT 2019zhd, a new merger in M 31 ', Astronomy and Astrophysics, vol. 646, A119 . https://doi.org/10.1051/0004-6361/202039952
- Accession number :
- edsair.doi.dedup.....f13cfe277fb898b3cdd68dca1da2d0e8