J/AJ/163/74 A census of the low accretors. I. The catalog (Thanathibodee+, 2022)
A census of the low accretors.
I. The catalog.
Thanathibodee T., Calvet N., Hernandez J., Mauco K., Briceno C.
<Astron. J., 163, 74-74 (2022)>
=2022AJ....163...74T 2022AJ....163...74T (SIMBAD/NED BibCode)
ADC_Keywords: Accretion; Stars, variable; Spectra, infrared; Stars, diameters;
Stars, masses; Effective temperatures; Extinction
Keywords: Accretion; Stellar accretion; Protoplanetary disks; T Tauri stars
Surveys
Abstract:
Observations have shown that the disk frequency and the fraction of
accreting pre-main-sequence stars decrease with the age of the
population and that some stars appear to have disks while their
accretion has stopped. Still, it is unclear how disk-bearing stars
stop their accretion. To provide insight into the last stages of
accretion in low-mass young stars, we conducted a survey of
disk-bearing stars that are thought to be non-accretors to identify
stars still accreting at very low rates. Here we present the first
catalog of the survey of 170 disk-bearing non-accreting stars in
Chamaeleon I, Orion OB1, Upper Scorpius, γ Velorum, and Upper
Centaurus-Lupus, using HeI λ10830 as a sensitive probe of
accretion. We classify the line profiles into six types and argue that
those showing redshifted and/or blueshifted absorption are still
accreting. Using these classifications, we found that, among
disk-bearing stars previously classified as non-accretors, at least
20%-30% are still accreting, with a larger fraction of those at
younger population ages. While the difference between the outer disk
signature and accretion status is unclear, we found a difference
between the inner disk excess and accretion status. There is no
preference in the mass of the newly identified accretors, suggesting
that the processes inhibiting accretion do not directly depend on mass
in the typical mass range of T Tauri stars. Lastly, we found that at a
low accretion level, the "Hα width at the 10% height" criterion
mischaracterizes a larger fraction of accretors than the line's
equivalent width.
Description:
We observed the targets during the 2018A, 2019A/B, and 2020A/B
semesters using the FIRE spectrograph at the Magellan Baade Telescope
at the Las Campanas Observatory in Chile. We used the 0.6" slit in the
echelle mode, which provided a spectral resolution of R∼6000 (∼50km/s)
for the wavelength range 0.9-2.4µm simultaneously.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 90 183 Log of observations
table4.dat 124 103 Line profile measurements
tablea1.dat 91 170 Properties of observed targets
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See also:
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 24 A24 --- ID The 2MASS or UGCS identifier
26- 36 A11 --- Name Alternative identifier
38- 39 I2 h RAh [05/16] Hour of Right Ascension (J2000)
41- 42 I2 min RAm Minute of Right Ascension (J2000)
44- 49 F6.3 s RAs Second of Right Ascension (J2000)
51- 51 A1 --- DE- [±] Sign of the Declination (J2000)
52- 53 I2 deg DEd Degree of Declination (J2000)
55- 56 I2 arcmin DEm Arcminute of Declination (J2000)
58- 62 F5.2 arcsec DEs Arcsecond of Declination (J2000)
64- 67 I4 yr Obs.Y [2018/2020] Year of the observation
69- 70 I2 "month" Obs.M Month of the observation
72- 73 I2 d Obs.D Day of the observation
75- 78 F4.2 --- Airmass [1.01/2.08] Airmass
80- 84 F5.1 s Texp [10/920] Exposure time
86- 90 F5.1 --- SNR [23.2/278] Signal-to-Noise
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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- 24 A24 --- ID The 2MASS or UGCS identifier
26- 36 A11 --- Name Alternate identifier
38- 41 I4 yr Obs.Y [2018/2020] Year of the observation
43- 44 I2 "month" Obs.M Month of the observation
46- 47 I2 d Obs.D Day of the observation
49- 50 A2 --- Type Profile type; see Section 3.2
52- 55 F4.1 0.1nm EWb [-2.7/1.5]? HeI(1.083um) blue equivalent width (1)
57- 60 F4.1 0.1nm EWc [-2.7/3.7]? HeI(1.083um) central equivalent width
(1)
62- 65 F4.1 0.1nm EWr [-4.7/1.2]? HeI(1.083um) red equivalent width (1)
67- 72 F6.1 km/s vbb [-344/-67.4]? Blue feature's blue velocity edge
74- 79 F6.1 km/s v0b [-182/-14.6]? Blue feature's velocity center
81- 86 F6.1 km/s vrb [-108/84.7]? Blue feature's red velocity edge
88- 93 F6.1 km/s vbc [-262/29.7]? Central feature's blue velocity edge
95- 99 F5.1 km/s v0c [-70.4/67.1]? Central feature's velocity center
101-105 F5.1 km/s vrc [8.8/229]? Central feature's red velocity edge
107-112 F6.1 km/s vbr [-118/148]? Red feature's blue velocity edge
114-118 F5.1 km/s v0r [15.8/220]? Red feature's velocity center
120-124 F5.1 km/s vrr [103/480]? Red feature's red velocity edge
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Note (1): A positive equivalent width refers to an emission feature, whereas
a negative one refers to absorption. In units of Angstroms.
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 24 A24 --- ID The 2MASS or UGCS identifier
26- 36 A11 --- Name Alternate identifier
38- 42 A5 --- SpType Spectral type
44- 45 I2 --- r_SpType Reference code for SpType (1)
47- 51 F5.2 0.1nm EW [-0.2/24.1]? Hα equivalent width
53- 54 I2 --- r_EW ? Reference code for EW (1)
56- 61 F6.2 km/s W10 [72/275]? Width at 10% Hα line peak
63- 64 I2 --- r_W10 ? Reference code for W10 (1)
66- 69 I4 K Teff [2860/5030] Effective temperature
71- 74 F4.2 mag AV [0/5.03] V band extinction
76- 77 I2 --- r_AV Reference code for AV (1)
79- 82 F4.2 solMass Mass [0.1/1.79] Mass
84- 87 F4.2 solRad Rad [0.45/3.23] Radius
89- 91 A3 --- Note Additional note (2)
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Note (1): References as follows:
1 = Briceno+, 2019, J/AJ/157/85
2 = Hernandez+, 2014, J/ApJ/794/36
3 = Ansdell+, 2017, J/AJ/153/240
4 = this study
5 = Frasca+, 2015, J/A+A/575/A4
6 = Hernandez+, 2008, J/ApJ/686/1195
7 = Esplin+, 2017, J/AJ/154/46
8 = Sacco+, 2017, J/A+A/601/A97
9 = Luhman, 2004, J/ApJ/602/816L
10 = Nguyen+, 2012, J/ApJ/745/119
11 = Pecaut & Mamajek, 2016, J/MNRAS/461/794
12 = Frasca+, 2017A&A...575A..33F 2017A&A...575A..33F
13 = Esplin+, 2018, J/AJ/156/75
Note (2): Stars marked with A are those with the equivalent width
larger than the threshold of White & Basri 2003ApJ...582.1109W 2003ApJ...582.1109W but are
included as they are classified as type CW by Briceno+, 2019,
J/AJ/157/85, weak accretor candidates by Hernandez+, 2014,
J/ApJ/794/36, or if their W10 are smaller than 200 km/s
(Jayawardhana+, 2006ApJ...648.1206J 2006ApJ...648.1206J). Those marked with B are stars
that are classified as non-accretors using the 270km/s criterion of
White & Basri, 2003ApJ...582.1109W 2003ApJ...582.1109W but are classified as accretors
using the 200km/s of Jayawardhana+, 2006.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 12-Apr-2022