SIMBAD references

2015ApJ...800..113K - Astrophys. J., 800, 113 (2015/February-3)

Pre-main-sequence accretion in the low metallicity galactic star-forming region Sh 2-284.

KALARI V.M. and VINK J.S.

Abstract (from CDS):

We present optical spectra of pre-main-sequence (PMS) candidates around the Hα region taken with the Southern African Large Telescope in the low metallicity (Z) Galactic region Sh 2-284, which includes the open cluster Dolidze 25 with an atypical low metallicity of Z ∼ 1/5 Z. It has been suggested on the basis of both theory and observations that PMS mass-accretion rates, {dot}Macc, are a function of Z. We present the first sample of spectroscopic estimates of mass-accretion rates for PMS stars in any low-Z star-forming region. Our data set was enlarged with literature data of Hα emission in intermediate-resolution R-band spectroscopy. Our total sample includes 24 objects spanning a mass range between 1 and 2 M and with a median age of approximately 3.5 Myr. The vast majority (21 out of 24) show evidence for a circumstellar disk on the basis of Two Micron All Sky Survey and Spitzer infrared photometry. We find {dot}Macc in the 1-2 Minterval to depend quasi-quadratically on stellar mass, with {dot}Macc ∝ {dot}M* ^2.4 ± 0.35^, and inversely with stellar age, with {dot}Macc ∝ t* ^-0.7 ± 0.4^. Furthermore, we compare our spectroscopic {dot}Macc measurements with solar Z Galactic PMS stars in the same mass range, but, surprisingly find no evidence for a systematic change in {dot}Macc with Z. We show that literature accretion-rate studies are influenced by detection limits, and we suggest that {dot}Macc may be controlled by factors other than Z*, M*, and age.

Abstract Copyright:

Journal keyword(s): accretion, accretion disks - stars: formation - stars: fundamental parameters - stars: pre-main sequence - stars: variables: T Tauri, Herbig Ae/Be

Simbad objects: 49

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2019.12.11-14:43:05

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