2022A&A...667A...4C

Query : 2022A&A...667A...4C

2022A&A...667A...4C - Astronomy and Astrophysics, volume 667A4 (2022/11-1)

Forbidden hugs in pandemic times III. Observations of the luminous red nova AT 2021biy in the nearby galaxy NGC 4631.

CAI Y.-Z., PASTORELLO A., FRASER M., WANG X.-F., FILIPPENKO A.V., REGUITTI A., PATRA K.C., GORANSKIJ V.P., BARSUKOVA E.A., BRINK T.G., ELIAS-ROSA N., STEVANCE H.F., ZHENG W., YANG Y., ATAPIN K.E., BENETTI S., DE BOER T.J.L., BOSE S., BURKE J., BYRNE R., CAPPELLARO E., CHAMBERS K.C., CHEN W.-L., EMAMI N., GAO H., HIRAMATSU D., HOWELL D.A., HUBER M.E., KANKARE E., KELLY P.L., KOTAK R., KRAVTSOV T., LANDER V.Y., LI Z.-T., LIN C.-C., LUNDQVIST P., MAGNIER E.A., MALYGIN E.A., MASLENNIKOVA N.A., MATILAINEN K., MAZZALI P.A., McCULLY C., MO J., MORAN S., NEWSOME M., OPARIN D.V., PADILLA GONZALEZ E., REYNOLDS T.M., SHATSKY N.I., SMARTT S.J., SMITH K.W., STRITZINGER M.D., TATARNIKOV A.M., TERRERAN G., UKLEIN R.I., VALERIN G., VALLELY P.J., VOZYAKOVA O.V., WAINSCOAT R., YAN S.-Y., ZHANG J.-J., ZHANG T.-M., ZHELTOUKHOV S.G., DASTIDAR R., FULTON M., GALBANY L., GANGOPADHYAY A., GE H.-W., GUTIERREZ C.P., LIN H., MISRA K., OU Z.-W., SALMASO I., TARTAGLIA L., XIAO L. and ZHANG X.-H.

Abstract (from CDS):

We present an observational study of the luminous red nova (LRN) AT 2021biy in the nearby galaxy NGC 4631. The field of the object was routinely imaged during the pre-eruptive stage by synoptic surveys, but the transient was detected only at a few epochs from ∼231 days before maximum brightness. The LRN outburst was monitored with unprecedented cadence both photometrically and spectroscopically. AT 2021biy shows a short-duration blue peak, with a bolometric luminosity of ∼1.6 × 1041 erg s–1, followed by the longest plateau among LRNe to date, with a duration of 210 days. A late-time hump in the light curve was also observed, possibly produced by a shell-shell collision. AT 2021biy exhibits the typical spectral evolution of LRNe. Early-time spectra are characterised by a blue continuum and prominent H emission lines. Then, the continuum becomes redder, resembling that of a K-type star with a forest of metal absorption lines during the plateau phase. Finally, late-time spectra show a very red continuum (TBB ≈ 2050 K) with molecular features (e.g., TiO) resembling those of M-type stars. Spectropolarimetric analysis indicates that AT 2021biy has local dust properties similar to those of V838 Mon in the Milky Way Galaxy. Inspection of archival Hubble Space Telescope data taken on 2003 August 3 reveals a ∼20 M⊙ progenitor candidate with log (L/L⊙) = 5.0 dex and Teff = 5900 K at solar metallicity. The above luminosity and colour match those of a luminous yellow supergiant. Most likely, this source is a close binary, with a 17-24 M⊙ primary component.

Abstract Copyright: © Y.-Z. Cai et al. 2022

Journal keyword(s): binaries: close - stars: winds, outflows - stars: individual: AT 2021biy

VizieR on-line data: <Available at CDS (J/A+A/667/A4): tablea1.dat-tablea13.dat>

Simbad objects: 18

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Number of rows : 18
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 AT 2018bwo ev 00 14 01.680 -23 11 35.38           ~ 22 0
2 M31N 2015-01a No* 00 42 07.99 +40 55 01.1           ~ 70 0
3 * 9 Gem s*b 06 16 58.7058631680 +23 44 27.284070336 6.31 6.70 6.25 5.78 5.38 B3Iab 253 0
4 V* V838 Mon CV* 07 04 04.8221494992 -03 50 50.648894412       15.181 14.51 M10+B3V 462 1
5 HD 57702 * 07 23 24.5992546368 +25 30 58.499547012   8.84 8.88     B9 16 0
6 HD 58624 * 07 27 02.9639802744 +16 05 57.981401592   9.14 9.21     B3III 9 0
7 AT 2018hso ev 11 33 51.96 +53 07 07.1           ~ 17 0
8 NAME M85 OT2006-1 No* 12 25 23.82 +18 10 56.2     19.30     ~ 70 1
9 SN 2017jfs SN* 12 29 37.78 +07 49 35.1           SNIIn 31 0
10 AT 2011kp ev 12 30 41.85 +41 37 49.8           ~ 45 0
11 ATLAS 21dfy ev 12 42 04.025 +32 32 07.88           ~ 12 0
12 NGC 4631 GiC 12 42 08.009 +32 32 29.44   9.78 9.19 9.10   ~ 1154 3
13 [M60b]+33 369 * 12 43 11.4667261584 +32 55 47.721865944   12.89 12.85 12.51   F5 5 0
14 NAME M101 OT2015-1 SN? 14 02 16.78 +54 26 20.5   19.19 17.57 16.92 16.26 ~ 51 0
15 AT 2014ib SN? 14 59 59.47 +01 54 26.6           ~ 43 1
16 AT 2020kog ? 16 18 47.652 +07 25 16.86           ~ 10 0
17 V* V1309 Sco CV* 17 57 32.9368332984 -30 43 09.965039880           ~ 320 0
18 V* V4332 Sgr CV* 18 50 36.6958376520 -21 23 28.925017944         14.37 K8/M0e 194 0

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