Opt. spectra of blue MIR objects in LMC

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.