Red Stellar Populations and Dust Extinction toward W3
We explore red stellar populations toward the W3 giant molecular cloud through the use of optical-to-infrared (IR) photometry and Gaia DR 3 data, simultaneously characterizing stellar content and properties of dust in the molecular medium. We use a Rayleigh–Jeans color excess method modified to de-r...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ad8ebb |
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| author | J. L. Campbell P. G. Martin S. Song M. Rahman L. Einstein |
| author_facet | J. L. Campbell P. G. Martin S. Song M. Rahman L. Einstein |
| author_sort | J. L. Campbell |
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| description | We explore red stellar populations toward the W3 giant molecular cloud through the use of optical-to-infrared (IR) photometry and Gaia DR 3 data, simultaneously characterizing stellar content and properties of dust in the molecular medium. We use a Rayleigh–Jeans color excess method modified to de-redden stellar observations of both red giants (RGs) and OB stars, and construct an IR Hertzsprung–Russell diagram validated against the Besançon Galactic model. Taking advantage of the near-universal IR interstellar extinction law and precise Gaia measurements, we develop a method for obtaining the spectral classification, foreground extinction, and distance moduli of stars, validated by spectroscopically confirmed OB stars. We constrain the observed parallax and proper motion of OB stars in W3, demonstrating the importance of considering systematic effects in the parallax bias, and assign parallax- and proper-motion-based cloud membership to our stellar samples. While it has been assumed that all spectroscopic OB stars are inside the W3 cloud, we find evidence of seven background B stars and three potential runaway OB stars. The methods developed here, which are based on known stellar populations, enable us to identify 82 new OB candidates that are confidently within the cloud. We quantify several dust-to-dust empirical correlations, in particular the IR color excess E ( H − [4.5]) and the optical depth τ _1 of submillimeter dust emission at 1 THz using RGs behind W3, measuring a best fit of $E(H-[4.5])=(1.07\pm 0.04)\times {10}^{3}\,{{\tau }_{1}}_{,{\rm{HOTT}}}+(0.00\pm 0.02)\,{\rm{mag}}$ . |
| format | Article |
| id | doaj-art-e3081f4c8ac14c2ab595505ac2fe3012 |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj-art-e3081f4c8ac14c2ab595505ac2fe30122025-01-15T15:04:44ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0197913310.3847/1538-4357/ad8ebbRed Stellar Populations and Dust Extinction toward W3J. L. Campbell0https://orcid.org/0000-0002-2511-5256P. G. Martin1https://orcid.org/0000-0002-5236-3896S. Song2https://orcid.org/0009-0001-0559-4392M. Rahman3https://orcid.org/0000-0003-1842-6096L. Einstein4https://orcid.org/0009-0005-6205-5810David A. Dunlap Department of Astronomy & Astrophysics, University of Toronto , 50 St. George Street, Toronto, ON M5S 3H4, Canada ; campbell@astro.utoronto.ca; Canadian Institute for Theoretical Astrophysics, University of Toronto , 60 St. George Street, Toronto, ON M5S 3H8, CanadaCanadian Institute for Theoretical Astrophysics, University of Toronto , 60 St. George Street, Toronto, ON M5S 3H8, CanadaDepartment of Information Technology and Electrical Engineering, ETH Zurich , Gloriastrasse 35, 8092 Zurich, SwitzerlandSidrat Research , 124 Merton Street, Suite 507, Toronto, ON M4S 2Z2, CanadaStanford Intelligent Systems Laboratory , Durand Building, 496 Lomita Mall, Stanford, CA 94305, USAWe explore red stellar populations toward the W3 giant molecular cloud through the use of optical-to-infrared (IR) photometry and Gaia DR 3 data, simultaneously characterizing stellar content and properties of dust in the molecular medium. We use a Rayleigh–Jeans color excess method modified to de-redden stellar observations of both red giants (RGs) and OB stars, and construct an IR Hertzsprung–Russell diagram validated against the Besançon Galactic model. Taking advantage of the near-universal IR interstellar extinction law and precise Gaia measurements, we develop a method for obtaining the spectral classification, foreground extinction, and distance moduli of stars, validated by spectroscopically confirmed OB stars. We constrain the observed parallax and proper motion of OB stars in W3, demonstrating the importance of considering systematic effects in the parallax bias, and assign parallax- and proper-motion-based cloud membership to our stellar samples. While it has been assumed that all spectroscopic OB stars are inside the W3 cloud, we find evidence of seven background B stars and three potential runaway OB stars. The methods developed here, which are based on known stellar populations, enable us to identify 82 new OB candidates that are confidently within the cloud. We quantify several dust-to-dust empirical correlations, in particular the IR color excess E ( H − [4.5]) and the optical depth τ _1 of submillimeter dust emission at 1 THz using RGs behind W3, measuring a best fit of $E(H-[4.5])=(1.07\pm 0.04)\times {10}^{3}\,{{\tau }_{1}}_{,{\rm{HOTT}}}+(0.00\pm 0.02)\,{\rm{mag}}$ .https://doi.org/10.3847/1538-4357/ad8ebbGiant molecular cloudsMolecular gasInterstellar dustInterstellar dust extinctionInfrared astronomyOptical astronomy |
| spellingShingle | J. L. Campbell P. G. Martin S. Song M. Rahman L. Einstein Red Stellar Populations and Dust Extinction toward W3 The Astrophysical Journal Giant molecular clouds Molecular gas Interstellar dust Interstellar dust extinction Infrared astronomy Optical astronomy |
| title | Red Stellar Populations and Dust Extinction toward W3 |
| title_full | Red Stellar Populations and Dust Extinction toward W3 |
| title_fullStr | Red Stellar Populations and Dust Extinction toward W3 |
| title_full_unstemmed | Red Stellar Populations and Dust Extinction toward W3 |
| title_short | Red Stellar Populations and Dust Extinction toward W3 |
| title_sort | red stellar populations and dust extinction toward w3 |
| topic | Giant molecular clouds Molecular gas Interstellar dust Interstellar dust extinction Infrared astronomy Optical astronomy |
| url | https://doi.org/10.3847/1538-4357/ad8ebb |
| work_keys_str_mv | AT jlcampbell redstellarpopulationsanddustextinctiontowardw3 AT pgmartin redstellarpopulationsanddustextinctiontowardw3 AT ssong redstellarpopulationsanddustextinctiontowardw3 AT mrahman redstellarpopulationsanddustextinctiontowardw3 AT leinstein redstellarpopulationsanddustextinctiontowardw3 |