J/ApJ/875/51 Mass accretion rates of PMS stars. VI. LH95 in LMC (Biazzo+, 2019)
Photometric determination of the mass accretion rates of pre-main-sequence
stars.
VI. The case of LH 95 in the Large Magellanic Cloud.
Biazzo K., Beccari G., De Marchi G., Panagia N.
<Astrophys. J., 875, 51 (2019)>
=2019ApJ...875...51B 2019ApJ...875...51B
ADC_Keywords: Magellanic Clouds; Accretion; Stars, pre-main sequence;
Photometry, HST; Photometry, VRI; Photometry, H-alpha;
Associations, stellar; Stars, masses; Stars, ages
Keywords: accretion, accretion disks ; Magellanic Clouds ;
open clusters and associations: individual (LH95) ; stars: formation ;
stars: pre-main sequence
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 (dM/dtacc). We
identify two different stellar populations: younger than ∼8Myr with
median dM/dtacc∼5.4x10-8M☉/yr (and M*∼0.15-1.8M☉)
and older than ∼8Myr with median dM/dtacc∼4.8x10-9M☉/yr (and
M*∼0.6-1.2M☉). 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 dM/dtacc 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 dM/dtacc-M* relationship shows
different behavior at different ages, becoming progressively steeper
at older ages, indicating that the effects of mass and age on
dM/dtacc cannot be treated independently. With the aim to identify
reliable correlations between mass, age, and dM/dtacc, 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 dM/dtacc
evolution in clusters with different environmental conditions.
Description:
The data were collected as part of HST programs 10566 (PI: Gouliermis;
2006 Mar 2 and 6), 12872 (PI: Da Rio; 2013 May 26, 28-30), and
13009 (PI: De Marchi; 2013 May 26). The LH 95 region was observed with
the Wide-Field Channel (WFC) of the Advanced Camera for Surveys (ACS)
in the narrowband filter F658N (centered on the Hα line) and the
wideband filters F555W and F814W, equivalent to the standard Johnson V
and I bands, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 114 245 Stellar parameters of our sample of low-mass
pre-main-sequence (PMS) accreting candidates
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+A/333/231 : O-M stars model atmospheres (Bessell+ 1998)
J/AJ/129/907 : New Ori OB1 members (Briceno+, 2005)
J/ApJ/661/1119 : Spectroscopy in the 25 Ori group (Briceno+, 2007)
J/ApJS/173/104 : Stellar population in Chamaeleon I (Luhman, 2007)
J/ApJ/710/597 : Accretion in disks in Cep OB2 (Sicilia-Aguilar+, 2010)
J/MNRAS/415/103 : IPHAS T Tauri candidates in IC 1396 (Barentsen+, 2011)
J/A+A/525/A47 : U-band photometry in sigma Orionis region (Rigliaco+, 2011)
J/A+A/533/A109 : Pisa pre-main sequence tracks & isochrones (Tognelli+, 2011)
J/ApJ/746/29 : High-resolution GC abundances. IV. 8 LMC GCs (Colucci+, 2012)
J/MNRAS/421/78 : LMC PMS stars mass accretion rates (Spezzi+, 2012)
J/MNRAS/429/1981 : NGC 2264 T Tauri star properties (Barentsen+, 2013)
J/ApJS/207/5 : YSOs in LDN 1641 with Hectochelle spectra (Fang+, 2013)
J/AJ/146/85 : Spectral types of 1576 opt. stars in ONC (Hillenbrand+, 2013)
J/ApJS/208/9 : Intrinsic colors & temperatures of PMS stars (Pecaut+, 2013)
J/A+A/561/A2 : 36 accreting YSOs emission lines (Alcala+, 2014)
J/MNRAS/442/1663 : Velocities of red giants in the SMC (Dobbie+, 2014)
J/A+A/580/A26 : T Tauri star population in Lupus (Galli+, 2015)
J/A+A/600/A20 : Lupus YSOs X-shooter spectroscopy (Alcala+, 2017)
J/ApJ/847/31 : Protoplanetary disk data in Cha I and Lupus (Mulders+, 2017)
J/AJ/157/85 : CIDA Variability Survey of Orion OB1. II. (Briceno+, 2019)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 1 I1 --- Set [1/2] Candidate subset population (1)
3- 8 I6 --- ID [100583/206419] Object ID within our catalog
10- 17 F8.5 deg RAdeg [84.19/84.34] Right Ascension (J2000)
19- 27 F9.5 deg DEdeg [-66.4/-66.3] Declination (J2000)
29- 34 F6.3 mag F555Wmag [21.87/26.55] Dereddened HST F555W magnitude
36- 40 F5.3 mag e_F555Wmag [0.01/0.1] Uncertainty in F555Wmag
42- 47 F6.3 mag F814Wmag [20.73/25.4] Dereddened HST F814W magnitude
49- 53 F5.3 mag e_F814Wmag [0.01/0.07] Uncertainty in F814Wmag
55- 60 F6.3 mag F658Nmag [20.72/25.11] Dereddened HST F658N magnitude
62- 66 F5.3 mag e_F658Nmag [0.003/0.3] Uncertainty in F658Nmag
68- 71 F4.1 0.1nm EWHa [12.7/66.5] Equivalent width, Hα,
in Angstroms
73- 75 F3.1 0.1nm e_EWHa [0.4/3.3] Uncertainty in EWHa
77- 80 I4 K Teff [3135/7323] Stellar effective temperature
82- 84 I3 K e_Teff [10/183] Uncertainty in Teff
86- 89 F4.2 Lsun Lstar [0.08/5.83] Stellar luminosity
91- 94 F4.2 Lsun e_Lstar [0.01/0.2] Uncertainty in Lstar
96- 98 F3.1 Msun Mstar [0.2/1.8] Stellar mass
100-100 A1 --- l_logt [> ] Limit flag on logt
102-104 F3.1 [yr] logt [3.6/7.8] Log of age
106-109 F4.1 [Lsun] logLacc [-1.3/0.5] Log of accretion luminosity
111-114 F4.1 [Msun/yr] logMacc [-8.7/-5.7] Log of measured accretion rate
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Note (1): The sample of PMS accreting candidates are divided into two
populations as follows:
1 = Younger than 8Myr PMS candidates (85 occurrences);
2 = Older than 8Myr PMS candidates (160 occurrences).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Sep-2020