Candidate LBV stars in galaxy NGC 7793 found via HST photometry + MUSE spectroscopy

• Verfasst von: Wofford, Aida [VerfasserIn]
• Verfasst von: Ramírez, Vanesa [VerfasserIn]
• Verfasst von: Lee, Janice C [VerfasserIn]
• Verfasst von: Thilker, David A [VerfasserIn]
• Verfasst von: Della Bruna, Lorenza [VerfasserIn]
• Verfasst von: Adamo, Angela [VerfasserIn]
• Verfasst von: Van Dyk, Schuyler D [VerfasserIn]
• Verfasst von: Herrero, Artemio [VerfasserIn]
• Verfasst von: Kim, Hwihyun [VerfasserIn]
• Verfasst von: Aloisi, Alessandra [VerfasserIn]
• Verfasst von: Calzetti, Daniela [VerfasserIn]
• Verfasst von: Chandar, Rupali [VerfasserIn]
• Verfasst von: Dale, Daniel A [VerfasserIn]
• Verfasst von: de Mink, Selma E [VerfasserIn]
• Verfasst von: Gallagher, John S [VerfasserIn]
• Verfasst von: Gouliermis, Dimitrios A. [VerfasserIn]
• Verfasst von: Grasha, Kathryn [VerfasserIn]
• Verfasst von: Grebel, Eva K. [VerfasserIn]
• Verfasst von: Sacchi, E [VerfasserIn]
• Verfasst von: Smith, Linda J [VerfasserIn]
• Verfasst von: Úbeda, Leonardo [VerfasserIn]
• Verfasst von: Walterbos, Rene A M [VerfasserIn]
• Verfasst von: Hannon, Stephen [VerfasserIn]
• Verfasst von: Messa, Matteo [VerfasserIn]
• Titel: Candidate LBV stars in galaxy NGC 7793 found via HST photometry + MUSE spectroscopy
• Verf.angabe: Aida Wofford, Vanesa Ramírez, Janice C Lee, David A Thilker, Lorenza Della Bruna, Angela Adamo, Schuyler D Van Dyk, Artemio Herrero, Hwihyun Kim, Alessandra Aloisi, Daniela Calzetti, Rupali Chandar, Daniel A Dale, Selma E de Mink, John S Gallagher, Dimitrios A Gouliermis, Kathryn Grasha, Eva K Grebel, E Sacchi, Linda J Smith, Leonardo Úbeda, Rene A M Walterbos, Stephen Hannon and Matteo Messa
• E-Jahr: 2020
• Jahr: 2020 February 3
• Umfang: 19 S.
• Fussnoten: Gesehen am 15.04.2020
• Titel Quelle: Enthalten in: Royal Astronomical SocietyMonthly notices of the Royal Astronomical Society
• Ort Quelle: Oxford : Oxford Univ. Press, 1827
• Jahr Quelle: 2020
• Band/Heft Quelle: 493(2020), 2 vom: Apr., Seite 2410-2428
• ISSN Quelle: 1365-2966
• DOI: doi:10.1093/mnras/staa290
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1754993567

Abstract

Only about 19 Galactic and 25 extragalactic bonafide luminous blue variables (LBVs) are known to date. This incomplete census prevents our understanding of this crucial phase of massive star evolution which leads to the formation of heavy binary black holes via the classical channel. With large samples of LBVs one could better determine the duration and maximum stellar luminosity which characterize this phase. We search for candidate LBVs (cLBVs) in a new galaxy, NGC 7793. For this purpose, we combine high spatial resolution images from two Hubble Space Telescope (HST) programs with optical spectroscopy from the Multi Unit Spectroscopic Explorer (MUSE). By combining PSF-fitting photometry measured on F547M, F657N, and F814W images, with restrictions on point-like appearance (at HST resolution) and H α luminosity, we find 100 potential cLBVs, 36 of which fall in the MUSE fields. Five of the latter 36 sources are promising cLBVs which have MV ≤ −7 and a combination of: H α with a P-Cygni profile; no [O i]$\, \lambda 6300$ emission; weak or no [O iii]$\, \lambda 5007$ emission; large [N ii]/H α relative to H ii regions; and [S ii]$\, \lambda 6716$/[S ii]$\, \lambda 6731\sim 1$. It is not clear if these five cLBVs are isolated from O-type stars, which would favour the binary formation scenario of LBVs. Our study, which approximately covers one fourth of the optical disc of NGC 7793, demonstrates how by combining the above HST surveys with multi-object spectroscopy from 8-m class telescopes, one can efficiently find large samples of cLBVs in nearby galaxies.