Opt. spectra of blue MIR objects in LMC


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; 2009, J/ApJS/184/172), 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 4.1m Telescope at Cerro Pachon and the Blanco 4m 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.

Cone search capability for table J/ApJS/265/18/blue (Blue stars with IR excesses (Table 1), estimates from photometric data (Table 3), environments & classification (Table 4) and classifications from literature (Table 5))

Cone search capability for table J/ApJS/265/18/tablea1 (List of 13 additional targets without U-B<0)

Cone search capability for table J/ApJS/265/18/tablea2 (List of 19 targets which were not observed)

DOI http://doi.org/10.26093/cds/vizier.22650018
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/ApJS/265/18
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/265/18
Related Identifier http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/265/18
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/J/ApJS/265/18
Creator Ishioka R.; Chu Y.-H.; Edmister A.; Gruendl R.A.; Zhang L.; Zhu J.
Publisher CDS
Publication Year 2023
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Galactic and extragalactic Astronomy; Interdisciplinary Astronomy; Interstellar medium; Natural Sciences; Observational Astronomy; Physics; Stellar Astronomy