Photometric Determination of the Mass Accretion Rates of Pre-main-sequence Stars. VI. The Case of LH 95 in the Large Magellanic Cloud
Journal
Date Issued
2019
Author(s)
Abstract
We report on the accretion properties of low-mass stars in the LH 95 association within the Large Magellanic Cloud. Using noncontemporaneous wideband optical and narrowband Hα photometry obtained with the Hubble Space Telescope, we identify 245 low-mass pre-main-sequence (PMS) candidates showing Hα excess emission above the 4σ level. We derive their physical parameters, including effective temperatures, luminosities, masses (M ⋆), ages, accretion luminosities, and mass accretion rates ({\dot{M}}acc}). We identify two different stellar populations: younger than ∼8 Myr with median {\dot{M}}acc}∼ 5.4× {10}-8 {M}☉ yr-1 (and M ⋆ ∼ 0.15-1.8 M ☉) and older than ∼8 Myr with median {\dot{M}}acc}∼ 4.8× {10}-9 {M}☉ yr-1 (and M ⋆ ∼ 0.6-1.2 M ☉). We find that the younger PMS candidates are assembled in groups around Be stars, while older PMS candidates are uniformly distributed within the region without evidence of clustering. We find that {\dot{M}}acc} in LH 95 decreases with time more slowly than what is observed in Galactic star-forming regions (SFRs). This agrees with the recent interpretation, according to which higher metallicity limits the accretion process in both rate and duration due to higher radiation pressure. The {\dot{M}}acc}-M ⋆ relationship shows different behavior at different ages, becoming progressively steeper at older ages, indicating that the effects of mass and age on {\dot{M}}acc} cannot be treated independently. With the aim to identify reliable correlations between mass, age, and {\dot{M}}acc}, we used a multivariate linear regression fit between these parameters for our PMS candidates. The comparison between our results and those obtained in other SFRs of our Galaxy and the Magellanic Clouds confirms the importance of the metallicity for the study of the {\dot{M}}acc} evolution in clusters with different environmental conditions.
Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
Volume
875
Issue
1
Start page
51
Issn Identifier
0004-637X
Ads BibCode
2019ApJ...875...51B
Rights
open.access
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