J/MNRAS/453/1026 Lagoon Nebula M8 T tauri accretion rates (Kalari+, 2015)
Classical T Tauri stars with VPHAS+.
I. Hα and u-band accretion rates in the Lagoon Nebula M8.
Kalari V.M., Vink J.S., Drew J.E., Barentsen G., Drake J.J., Eisloffel J.,
Martin E.L., Parker Q.A., Unruh Y.C., Walton N.A., Wright N.J.
<Mon. Not. R. Astron. Soc., 453, 1026-1046 (2015)>
=2015MNRAS.453.1026K 2015MNRAS.453.1026K (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Accretion ;
Photometry, ugriz ; Photometry, H-alpha
Keywords: accretion, accretion discs - stars: pre-main-sequence -
stars: variables: T Tauri, Herbig Ae/Be -
open clusters and associations: individual: NGC 6530
Abstract:
We estimate the accretion rates of 235 Classical T Tauri star (CTTS)
candidates in the Lagoon Nebula using ugri Hα photometry
from the VST Photometric Hα survey+. Our sample consists of
stars displaying Hα excess, the intensity of which is used to
derive accretion rates. For a subset of 87 stars, the intensity of the
u-band excess is also used to estimate accretion rates. We find
the mean variation in accretion rates measured using Hα and
u-band intensities to be ∼0.17dex, agreeing with previous
estimates (0.04-0.4dex) but for a much larger sample. The spatial
distribution of CTTS align with the location of protostars and
molecular gas suggesting that they retain an imprint of the natal gas
fragmentation process. Strong accretors are concentrated spatially,
while weak accretors are more distributed. Our results do not support
the sequential star-forming processes suggested in the literature.
Description:
VPHAS+ imaging is obtained by the OmegaCAM CCD imager mounted on the
2.6m VLT Survey Telescope (VST) on Cerro Paranal, Chile. The imager
captures a 1° square field of view at a resolution of
0.21arcsec/pix. Each pointing is supplemented by at least one offset
exposure to minimize CCD gaps. Imaging is carried out through
broad-band ugri filters and a purpose-built Hα filter. The
central wavelength and bandpass of the Hα filter are 6588 and
107Å, respectively. Exposure times are 150, 30, 25, 25, and 120s,
respectively. VPHAS+ reaches a 5σ depth at Hα=20.5-21.0mag
and g=22.2-22.7mag. Practical constraints have meant that the blue
(ug) and red (riHα) observations are carried out separately. An
additional r observation is carried out with every blue observation to
serve as a linking reference.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 99 235 VPHAS+ photometry of candidate CTTS in the
Lagoon Nebula
table4.dat 69 235 Derived properties of candidate CTTS in the
Lagoon Nebula
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See also:
J/A+A/395/499 : XMM observations in M8 and NGC6530 (Rauw+, 2002)
J/ApJ/747/51 : Lagoon Nebula stars. I. Rotation periods (Henderson+, 2012)
J/MNRAS/440/2036 : VPHAS+ survey synthetic colours (Drew+, 2014)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Name Name (HHMMSsss+DDMMSSs)
19- 27 F9.5 deg RAdeg Right ascension (J2000)
29- 37 F9.5 deg DEdeg Declination (J2000)
40- 44 F5.2 mag rmag r magnitude
46- 50 F5.3 mag e_rmag rms uncertainty on rmag
52- 56 F5.2 mag r-i r-i colour index
58- 62 F5.3 mag e_r-i rms uncertainty on r-i
64- 68 F5.2 mag r-Ha r-Hα colour index
70- 74 F5.3 mag e_r-Ha rms uncertainty on r-Hα
76- 80 F5.2 mag g-r ?=- g-r colour index
82- 87 F6.4 mag e_g-r ? rms uncertainty on g-r
88- 92 F5.2 mag u-g ?=- u-g colour index
94- 99 F6.4 mag e_u-g ? rms uncertainty on u-g
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Name Name (HHMMSsss+DDMMSSs)
18- 24 F7.2 0.1nm EWHa Equivalent width of Hα
26- 30 F5.2 0.1nm e_EWHa rms uncertainty on EWHα
32- 34 F3.1 Msun Mass Mass
36- 39 F4.2 Msun e_Mass rms uncertainty on Mass
42- 44 F3.1 [yr] logAge Age
46- 49 F4.2 [yr] e_logAge rms uncertainty on logAge
52- 55 F4.1 Msun/yr (dMac/dt)Ha Accretion rate derived from Hα
57- 59 F3.1 Msun/yr e_(dMac/dt)Ha rms uncertainty on (dMac/dt)Ha
62- 65 F4.1 Msun/yr (dMac/dt)u ? Accretion rate derived from u-band
67- 69 F3.1 Msun/yr e_(dMac/dt)u ? rms uncertainty on (dMac/dt)u
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 15-Mar-2016