{"_id":"13451","doi":"10.3847/1538-4357/aca295","intvolume":"       941","scopus_import":"1","publisher":"American Astronomical Society","author":[{"last_name":"Gull","first_name":"Maude","full_name":"Gull, Maude"},{"last_name":"Weisz","first_name":"Daniel R.","full_name":"Weisz, Daniel R."},{"last_name":"Senchyna","full_name":"Senchyna, Peter","first_name":"Peter"},{"full_name":"Sandford, Nathan R.","first_name":"Nathan R.","last_name":"Sandford"},{"full_name":"Choi, Yumi","first_name":"Yumi","last_name":"Choi"},{"first_name":"Anna F.","full_name":"McLeod, Anna F.","last_name":"McLeod"},{"first_name":"Kareem","full_name":"El-Badry, Kareem","last_name":"El-Badry"},{"last_name":"Götberg","orcid":"0000-0002-6960-6911","full_name":"Götberg, Ylva Louise Linsdotter","first_name":"Ylva Louise Linsdotter","id":"d0648d0c-0f64-11ee-a2e0-dd0faa2e4f7d"},{"full_name":"Gilbert, Karoline M.","first_name":"Karoline M.","last_name":"Gilbert"},{"full_name":"Boyer, Martha","first_name":"Martha","last_name":"Boyer"},{"last_name":"Dalcanton","full_name":"Dalcanton, Julianne J.","first_name":"Julianne J."},{"full_name":"GuhaThakurta, Puragra","first_name":"Puragra","last_name":"GuhaThakurta"},{"last_name":"Goldman","first_name":"Steven","full_name":"Goldman, Steven"},{"full_name":"Marigo, Paola","first_name":"Paola","last_name":"Marigo"},{"full_name":"McQuinn, Kristen B. W.","first_name":"Kristen B. W.","last_name":"McQuinn"},{"last_name":"Pastorelli","full_name":"Pastorelli, Giada","first_name":"Giada"},{"last_name":"Stark","first_name":"Daniel P.","full_name":"Stark, Daniel P."},{"last_name":"Skillman","first_name":"Evan","full_name":"Skillman, Evan"},{"last_name":"Ting","first_name":"Yuan-sen","full_name":"Ting, Yuan-sen"},{"last_name":"Williams","full_name":"Williams, Benjamin F.","first_name":"Benjamin F."}],"language":[{"iso":"eng"}],"date_updated":"2023-08-21T12:04:58Z","article_number":"206","abstract":[{"lang":"eng","text":"We characterize massive stars (M > 8 M⊙) in the nearby (D ∼ 0.8 Mpc) extremely metal-poor (Z ∼ 5% Z⊙) galaxy Leo A using Hubble Space Telescope ultraviolet (UV), optical, and near-infrared (NIR) imaging along with Keck/Low-Resolution Imaging Spectrograph and MMT/Binospec optical spectroscopy for 18 main-sequence OB stars. We find that: (a) 12 of our 18 stars show emission lines, despite not being associated with an H ii region, suggestive of stellar activity (e.g., mass loss, accretion, binary star interaction), which is consistent with previous predictions of enhanced activity at low metallicity; (b) six are Be stars, which are the first to be spectroscopically studied at such low metallicity—these Be stars have unusual panchromatic SEDs; (c) for stars well fit by the TLUSTY nonlocal thermodynamic equilibrium models, the photometric and spectroscopic values of $\\mathrm{log}({T}_{\\mathrm{eff}})$ and $\\mathrm{log}(g)$ agree to within ∼0.01 dex and ∼0.18 dex, respectively, indicating that near-UV/optical/NIR imaging can be used to reliably characterize massive (M ∼ 8–30 M⊙) main-sequence star properties relative to optical spectroscopy; (d) the properties of the most-massive stars in H II regions are consistent with constraints from previous nebular emission line studies; and (e) 13 stars with M > 8M⊙ are >40 pc from a known star cluster or H II region. Our sample comprises ∼50% of all known massive stars at Z ≲ 10% Z⊙with derived stellar parameters, high-quality optical spectra, and panchromatic photometry."}],"oa":1,"article_type":"original","quality_controlled":"1","year":"2022","publication_status":"published","day":"27","citation":{"ieee":"M. Gull <i>et al.</i>, “A panchromatic study of massive stars in the extremely metal-poor local group dwarf galaxy Leo A,” <i>The Astrophysical Journal</i>, vol. 941, no. 2. American Astronomical Society, 2022.","ista":"Gull M, Weisz DR, Senchyna P, Sandford NR, Choi Y, McLeod AF, El-Badry K, Götberg YLL, Gilbert KM, Boyer M, Dalcanton JJ, GuhaThakurta P, Goldman S, Marigo P, McQuinn KBW, Pastorelli G, Stark DP, Skillman E, Ting Y, Williams BF. 2022. A panchromatic study of massive stars in the extremely metal-poor local group dwarf galaxy Leo A. The Astrophysical Journal. 941(2), 206.","mla":"Gull, Maude, et al. “A Panchromatic Study of Massive Stars in the Extremely Metal-Poor Local Group Dwarf Galaxy Leo A.” <i>The Astrophysical Journal</i>, vol. 941, no. 2, 206, American Astronomical Society, 2022, doi:<a href=\"https://doi.org/10.3847/1538-4357/aca295\">10.3847/1538-4357/aca295</a>.","chicago":"Gull, Maude, Daniel R. Weisz, Peter Senchyna, Nathan R. Sandford, Yumi Choi, Anna F. McLeod, Kareem El-Badry, et al. “A Panchromatic Study of Massive Stars in the Extremely Metal-Poor Local Group Dwarf Galaxy Leo A.” <i>The Astrophysical Journal</i>. American Astronomical Society, 2022. <a href=\"https://doi.org/10.3847/1538-4357/aca295\">https://doi.org/10.3847/1538-4357/aca295</a>.","short":"M. Gull, D.R. Weisz, P. Senchyna, N.R. Sandford, Y. Choi, A.F. McLeod, K. El-Badry, Y.L.L. Götberg, K.M. Gilbert, M. Boyer, J.J. Dalcanton, P. GuhaThakurta, S. Goldman, P. Marigo, K.B.W. McQuinn, G. Pastorelli, D.P. Stark, E. Skillman, Y. Ting, B.F. Williams, The Astrophysical Journal 941 (2022).","ama":"Gull M, Weisz DR, Senchyna P, et al. A panchromatic study of massive stars in the extremely metal-poor local group dwarf galaxy Leo A. <i>The Astrophysical Journal</i>. 2022;941(2). doi:<a href=\"https://doi.org/10.3847/1538-4357/aca295\">10.3847/1538-4357/aca295</a>","apa":"Gull, M., Weisz, D. R., Senchyna, P., Sandford, N. R., Choi, Y., McLeod, A. F., … Williams, B. F. (2022). A panchromatic study of massive stars in the extremely metal-poor local group dwarf galaxy Leo A. <i>The Astrophysical Journal</i>. American Astronomical Society. <a href=\"https://doi.org/10.3847/1538-4357/aca295\">https://doi.org/10.3847/1538-4357/aca295</a>"},"status":"public","date_created":"2023-08-03T10:10:25Z","external_id":{"arxiv":["2211.14349"]},"publication":"The Astrophysical Journal","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","month":"12","keyword":["Space and Planetary Science","Astronomy and Astrophysics"],"issue":"2","volume":941,"oa_version":"Published Version","publication_identifier":{"eissn":["1538-4357"],"issn":["0004-637X"]},"title":"A panchromatic study of massive stars in the extremely metal-poor local group dwarf galaxy Leo A","article_processing_charge":"No","date_published":"2022-12-27T00:00:00Z","main_file_link":[{"url":"https://doi.org/10.3847/1538-4357/aca295","open_access":"1"}],"type":"journal_article","extern":"1"}