The Nature of Blue Stars with Mid-infrared Excesses in the Large Magellanic Cloud
We present low-resolution optical spectra and classifications of 92 blue objects with mid-infrared excesses in the Large Magellanic Cloud. The majority of these objects were selected with the criteria of U − B < 0 and V < 17 from the potential young stellar object (YSO) candidates in Gruendl &...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal Supplement Series |
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| Online Access: | https://doi.org/10.3847/1538-4365/acad06 |
| _version_ | 1797701377413087232 |
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| author | Ryoko Ishioka You-Hua Chu Austin Edmister Robert A. Gruendl Lizhong Zhang Ju Zhu |
| author_facet | Ryoko Ishioka You-Hua Chu Austin Edmister Robert A. Gruendl Lizhong Zhang Ju Zhu |
| author_sort | Ryoko Ishioka |
| collection | DOAJ |
| description | We present low-resolution optical spectra and classifications of 92 blue objects with mid-infrared excesses in the Large Magellanic Cloud. The majority of these objects were selected with the criteria of U − B < 0 and V < 17 from the potential young stellar object (YSO) candidates in Gruendl & Chu (GC09), which were identified based on Spitzer Infrared Array Camera and Multiband Imaging Photometer for Spitzer observations in conjunction with optical photometry from the Magellanic Clouds Photometric Survey. Many of the sample objects have ambiguous classifications. We examined the properties of these 92 objects using low-resolution optical spectra obtained with the SOAR 4.1 m Telescope at Cerro Pachon and the Blanco 4 m Telescope at Cerro Tololo Inter-American Observatory, supplemented by available photometric and imaging observations. We estimated the spectral types, temperatures, and luminosities of these objects from the optical to near-IR spectral energy distributions based on the photometric data, and further examined stellar absorption line features in the optical spectra to verify the spectral types. The interstellar/circumstellar environments, assessed from nebular line imaging observations and nebular lines detected in the stellar spectra, further helped constrain the nature of stars. Among these 92 objects, we confirm 42 stars as YSOs, and the remaining 50 objects as protoplanetary nebulae, post-AGB/RGB stars, blue evolved massive stars, stars with dust in vicinity, or uncertain classifications. Our results show that the photometric criteria in GC09 are generally effective in the initial selection of YSO candidates, and the low-resolution spectroscopy combined with environment assessment can be useful to better constrain the classifications and ameliorate most ambiguities. |
| first_indexed | 2024-03-12T04:35:46Z |
| format | Article |
| id | doaj.art-2b6e5994da794efe9d6b09288886ee02 |
| institution | Directory Open Access Journal |
| issn | 0067-0049 |
| language | English |
| last_indexed | 2024-03-12T04:35:46Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Supplement Series |
| spelling | doaj.art-2b6e5994da794efe9d6b09288886ee022023-09-03T09:56:16ZengIOP PublishingThe Astrophysical Journal Supplement Series0067-00492023-01-0126511810.3847/1538-4365/acad06The Nature of Blue Stars with Mid-infrared Excesses in the Large Magellanic CloudRyoko Ishioka0https://orcid.org/0000-0002-9902-0807You-Hua Chu1https://orcid.org/0000-0003-3667-574XAustin Edmister2Robert A. Gruendl3https://orcid.org/0000-0002-4588-6517Lizhong Zhang4https://orcid.org/0000-0003-0232-0879Ju Zhu5Institute of Astronomy and Astrophysics , Academia Sinica No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan ; ishioka@asiaa.sinica.edu.twInstitute of Astronomy and Astrophysics , Academia Sinica No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan ; ishioka@asiaa.sinica.edu.tw; Department of Astronomy, University of Illinois at Urbana-Champaign 1002 West Green Street, Urbana, IL 61801, USADetroit Observatory, University of Michigan 1398 East Ann Street, Ann Arbor, MI 48109, USADepartment of Astronomy, University of Illinois at Urbana-Champaign 1002 West Green Street, Urbana, IL 61801, USA; National Center for Supercomputing Applications 1205 West Clark Street, Urbana, IL 61801, USADepartment of Physics, University of California , Santa Barbara, CA 93106, USADepartment of Astronomy, University of Illinois at Urbana-Champaign 1002 West Green Street, Urbana, IL 61801, USAWe present low-resolution optical spectra and classifications of 92 blue objects with mid-infrared excesses in the Large Magellanic Cloud. The majority of these objects were selected with the criteria of U − B < 0 and V < 17 from the potential young stellar object (YSO) candidates in Gruendl & Chu (GC09), which were identified based on Spitzer Infrared Array Camera and Multiband Imaging Photometer for Spitzer observations in conjunction with optical photometry from the Magellanic Clouds Photometric Survey. Many of the sample objects have ambiguous classifications. We examined the properties of these 92 objects using low-resolution optical spectra obtained with the SOAR 4.1 m Telescope at Cerro Pachon and the Blanco 4 m Telescope at Cerro Tololo Inter-American Observatory, supplemented by available photometric and imaging observations. We estimated the spectral types, temperatures, and luminosities of these objects from the optical to near-IR spectral energy distributions based on the photometric data, and further examined stellar absorption line features in the optical spectra to verify the spectral types. The interstellar/circumstellar environments, assessed from nebular line imaging observations and nebular lines detected in the stellar spectra, further helped constrain the nature of stars. Among these 92 objects, we confirm 42 stars as YSOs, and the remaining 50 objects as protoplanetary nebulae, post-AGB/RGB stars, blue evolved massive stars, stars with dust in vicinity, or uncertain classifications. Our results show that the photometric criteria in GC09 are generally effective in the initial selection of YSO candidates, and the low-resolution spectroscopy combined with environment assessment can be useful to better constrain the classifications and ameliorate most ambiguities.https://doi.org/10.3847/1538-4365/acad06Large Magellanic CloudYoung stellar objectsStellar classification |
| spellingShingle | Ryoko Ishioka You-Hua Chu Austin Edmister Robert A. Gruendl Lizhong Zhang Ju Zhu The Nature of Blue Stars with Mid-infrared Excesses in the Large Magellanic Cloud The Astrophysical Journal Supplement Series Large Magellanic Cloud Young stellar objects Stellar classification |
| title | The Nature of Blue Stars with Mid-infrared Excesses in the Large Magellanic Cloud |
| title_full | The Nature of Blue Stars with Mid-infrared Excesses in the Large Magellanic Cloud |
| title_fullStr | The Nature of Blue Stars with Mid-infrared Excesses in the Large Magellanic Cloud |
| title_full_unstemmed | The Nature of Blue Stars with Mid-infrared Excesses in the Large Magellanic Cloud |
| title_short | The Nature of Blue Stars with Mid-infrared Excesses in the Large Magellanic Cloud |
| title_sort | nature of blue stars with mid infrared excesses in the large magellanic cloud |
| topic | Large Magellanic Cloud Young stellar objects Stellar classification |
| url | https://doi.org/10.3847/1538-4365/acad06 |
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