Disentangling the stellar atmosphere and the focused wind in different accretion states of Cygnus X-1

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F25%3A00618572" target="_blank" >RIV/67985815:_____/25:00618572 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216208:11320/25:10512582

Výsledek na webu

<a href="https://hdl.handle.net/11104/0365970" target="_blank" >https://hdl.handle.net/11104/0365970</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202450910" target="_blank" >10.1051/0004-6361/202450910</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Disentangling the stellar atmosphere and the focused wind in different accretion states of Cygnus X-1

Popis výsledku v původním jazyce

In high-mass X-ray binaries (HMXBs), the compact object accretes the strong stellar wind of an O-B supergiant companion star. X-ray flux variations alter the stellar wind's ionization state and optical line profiles, which are important in the determination of the orbital parameters of the system. Aims. We analyzed the state-dependent variability of the line profiles by separating the components coming from the star's atmosphere and the accreted stream of matter located between the star and the accretion disk (i.e. the focused wind). We then determined the radial velocities and the intensities of the absorption and emission lines with respect to the continuum. Methods. We performed optical high-resolution spectroscopy of the HMXB Cyg X-1 in the hard and soft-intermediate X-ray spectral states, respectively from 2022 and 2023, over multiple orbital phases. We then applied the method of Fourier disentangling to combine the spectra and isolate the stellar atmosphere and focused wind components. Results. We observe P-Cygni profiles of the H alpha line in the stellar atmosphere and a wide emission from the focused wind, indicating an outflowing material. While He I lambda 6678 is in absorption in the stellar atmosphere and not detected in the focused wind, we see a broad emission feature of He II lambda 4686 in the focused wind. Moreover, we identify an X-ray/optical anticorrelation traced by the strength of the line intensity. The intensity of the lines drops in the soft-intermediate spectral state and the lines are more absorbed at the inferior conjunction of the star. Conclusions. Our results confirm that the He II emission comes from the focused wind rather than the stellar atmosphere and is produced from the re-scattering of the resonance line due to high-density clumps in the focused wind. The X-ray/optical anticorrelation shows a stronger wind in the low-hard state and the lines are stronger at the inferior conjunction of the star.

Název v anglickém jazyce

Disentangling the stellar atmosphere and the focused wind in different accretion states of Cygnus X-1

Popis výsledku anglicky

In high-mass X-ray binaries (HMXBs), the compact object accretes the strong stellar wind of an O-B supergiant companion star. X-ray flux variations alter the stellar wind's ionization state and optical line profiles, which are important in the determination of the orbital parameters of the system. Aims. We analyzed the state-dependent variability of the line profiles by separating the components coming from the star's atmosphere and the accreted stream of matter located between the star and the accretion disk (i.e. the focused wind). We then determined the radial velocities and the intensities of the absorption and emission lines with respect to the continuum. Methods. We performed optical high-resolution spectroscopy of the HMXB Cyg X-1 in the hard and soft-intermediate X-ray spectral states, respectively from 2022 and 2023, over multiple orbital phases. We then applied the method of Fourier disentangling to combine the spectra and isolate the stellar atmosphere and focused wind components. Results. We observe P-Cygni profiles of the H alpha line in the stellar atmosphere and a wide emission from the focused wind, indicating an outflowing material. While He I lambda 6678 is in absorption in the stellar atmosphere and not detected in the focused wind, we see a broad emission feature of He II lambda 4686 in the focused wind. Moreover, we identify an X-ray/optical anticorrelation traced by the strength of the line intensity. The intensity of the lines drops in the soft-intermediate spectral state and the lines are more absorbed at the inferior conjunction of the star. Conclusions. Our results confirm that the He II emission comes from the focused wind rather than the stellar atmosphere and is produced from the re-scattering of the resonance line due to high-density clumps in the focused wind. The X-ray/optical anticorrelation shows a stronger wind in the low-hard state and the lines are stronger at the inferior conjunction of the star.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2025

Kód důvěrnosti údajů

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

Název periodika

Astronomy & Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Svazek periodika

695

Číslo periodika v rámci svazku

March

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

15

Strana od-do

A115

Kód UT WoS článku

001442985200012

EID výsledku v databázi Scopus

2-s2.0-86000780355