Variations in the intermediate wind region of the blue supergiant 55 Cygni

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F23%3A00577346" target="_blank" >RIV/67985815:_____/23:00577346 - isvavai.cz</a>

Result on the web

<a href="https://hdl.handle.net/11104/0346972" target="_blank" >https://hdl.handle.net/11104/0346972</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202245296" target="_blank" >10.1051/0004-6361/202245296</a>

Result language

angličtina

Original language name

Variations in the intermediate wind region of the blue supergiant 55 Cygni

Original language description

We seek to enhance our understanding of the wind properties of B supergiants. To this end, we propose analysing their NIR spectra over different epochs to study wind variability and its connection with phenomena arising from regions close to the photosphere. We present the first sets of multi-epoch high-resolution K- and L-band spectra of 55 Cyg acquired with the Gemini Near-InfraRed Spectrograph (GNIRS). We measured line equivalent widths and modelled the Brα line to derive (unclumped) mass-loss rates. Synthetic line profiles were computed for a homogeneous spherical wind by solving the radiative transfer equations in the co-moving frame for a multi-level atom in non-local thermodynamic equilibrium (NLTE). We observe variations in the spectral lines originating in the upper photosphere and the wind. The perturbations, on average, have periods of ~13 and ~23 days, the latter is similar to that found previously from optical data (22.5 days). The NIR lines observed in 2013 are described with the same wind structure used to model a quasi-simultaneous observation in Hα. By contrast, from observations taken in 2015, we derived a higher mean mass-loss rate. Variations in the mass-loss rate are also detected within a few weeks. Interestingly, we find that the profile shape of the Hu14 line sets constraints on the mass loss. Moreover, we find the Mg II doublet in emission, which suggests a tenuous circumstellar gas ring or shell.

Czech name

—

Czech description

—

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

<a href="/en/project/GA20-00150S" target="_blank" >GA20-00150S: Structure and evolution of stellar ejecta</a><br>

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2023

Confidentiality

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

Name of the periodical

Astronomy & Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Volume of the periodical

677

Issue of the periodical within the volume

September

Country of publishing house

FR - FRANCE

Number of pages

11

Pages from-to

A176

UT code for WoS article

001078962500001

EID of the result in the Scopus database

2-s2.0-85174184773