Young stellar objects in the Large Magellanic Cloud: N63 and N180HIIregions

We used Spitzer infrared observations to find the young stars of two H II regions in the Large Magellanic Cloud, N63 and N180. The young stellar object ( YSO) candidates were identified in each nebula by means of color- color, color- magnitude diagrams, and the shapes of their spectral energy distributions ( SEDs). The most luminous YSOs are found near the ionization fronts within strong 8 mu m emission clumps. Most YSOs, less luminous, are seen in projection inside the H II regions. HST images show several Class I stars that have emerged along the borders of the H II regions; other YSOs are embedded in cometary clouds. The most luminous YSO of N63 is connected to a string of pointlike sources. Its SED can be modeled by a central source of stellar mass M star between 7 and 11M(circle dot), with a circumstellar disk of outer radius R-d of similar to 55 AU, and an envelope of moderate accretion rate,. M-env of similar to 2x 10(-5) M-circle dot yr(-1). N180 is experiencing a phase of star formation more intense than N63, attested by the properties of its most luminous YSO: M star of 25 M-circle dot, R-d of similar to 200 AU, and. Menv of similar to 1: 5; 10(-3) M-circle dot yr(-1). The modes of triggered star formation in N63 and N180 appear similar to those seen in Galactic H II regions.