The luminous red nova AT 2018bwo in NGC 45 and its binary yellow supergiant progenitor

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F21%3A10438307" target="_blank" >RIV/00216208:11320/21:10438307 - isvavai.cz</a>

Result on the web

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=5t-L8Q.eyB" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=5t-L8Q.eyB</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202140525" target="_blank" >10.1051/0004-6361/202140525</a>

Result language

angličtina

Original language name

The luminous red nova AT 2018bwo in NGC 45 and its binary yellow supergiant progenitor

Original language description

Luminous red novae (LRNe) are astrophysical transients associated with the partial ejection of a binary system&apos;s common envelope shortly before its merger. Here we present the results of our photometric and spectroscopic follow-up campaign of AT 2018bwo (DLT 18x), a LRN discovered in NGC 45, and investigate its progenitor system using binary stellar-evolution models. The transient reached a peak magnitude of M-r = -10.97 +/- 0.11 and maintained this brightness during its optical plateau of t(p) = 41 +/- 5 days. During this phase, it showed a rather stable photospheric temperature of similar to 3300 K and a luminosity of similar to 10(40) erg s(-1). Although the luminosity and duration of AT 2018bwo is comparable to the LRNe V838 Mon and M31-2015LRN, its photosphere at early times appears larger and cooler, likely due to an extended mass-loss episode before the merger. Toward the end of the plateau, optical spectra showed a reddened continuum with strong molecular absorption bands. The IR spectrum at +103 days after discovery was comparable to that of a M8.5 II type star, analogous to an extended AGB star. The reprocessed emission by the cooling dust was also detected in the mid-infrared bands similar to 1.5 years after the outburst. Archival Spitzer and Hubble Space Telescope data taken 10-14 yrs before the transient event suggest a progenitor star with T-prog similar to 6500 K, R-prog similar to 100 R-circle dot, and L-prog = 2 x 10(4) L-circle dot, and an upper limit for optically thin warm (1000 K) dust mass of M-d &lt; 10(-6) M-circle dot. Using stellar binary-evolution models, we determined the properties of binary systems consistent with the progenitor parameter space. For AT 2018bwo, we infer a primary mass of 12-16 M-circle dot, which is 9-45% larger than the similar to 11 M-circle dot obtained using single-star evolution models. The system, consistent with a yellow-supergiant primary, was likely in a stable mass-transfer regime with -2.4 &lt;= log((M)over dot/M-circle dot yr(-1)) &lt;= -1.2 a decade before the main instability occurred. During the dynamical merger, the system would have ejected 0.15-0.5 M-circle dot with a velocity of similar to 500 km s(-1).

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

—

Continuities

R - Projekt Ramcoveho programu EK

Publication year

2021

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Astronomy &amp; Astrophysics

ISSN

0004-6361

e-ISSN

—

Volume of the periodical

653

Issue of the periodical within the volume

September

Country of publishing house

FR - FRANCE

Number of pages

21

Pages from-to

A134

UT code for WoS article

000698590500004

EID of the result in the Scopus database

2-s2.0-85116008311