J/ApJS/207/5 YSOs in LDN 1641 with Hectochelle spectra (Fang+, 2013)
Young stellar objects in Lynds 1641: disks, accretion, and star formation
history.
Fang M., Kim J.S., van Boekel R., Sicilia-Aguilar A., Henning T.,
Flaherty K.
<Astrophys. J. Suppl. Ser., 207, 5 (2013)>
=2013ApJS..207....5F 2013ApJS..207....5F
ADC_Keywords: Accretion ; Photometry, SDSS ; Photometry, infrared ; YSOs ;
Equivalent widths ; Spectral types ; Stars, ages ; Stars, masses
Keywords: accretion, accretion disks - protoplanetary disks -
stars: pre-main sequence
Abstract:
We investigate the young stellar objects (YSOs) in the Lynds 1641
(L1641) cloud using multi-wavelength data including Spitzer, WISE, the
Two Micron All Sky Survey, and XMM covering ∼1390 YSOs across a range
of evolutionary stages. In addition, we targeted a sub-sample of YSOs
for optical spectroscopy with the MMT/Hectospec and the
MMT/Hectochelle. We use these data, along with archival photometric
data, to derive spectral types, extinction values, masses, ages, and
accretion rates. We obtain a disk fraction of ∼50% in L1641. The disk
frequency is almost constant as a function of stellar mass with a
slight peak at log (M*/M☉)~-0.25. The analysis of
multi-epoch spectroscopic data indicates that the accretion
variability of YSOs cannot explain the two orders of magnitude of
scatter for YSOs with similar masses. Forty-six new transition disk
(TD) objects are confirmed in this work, and we find that the fraction
of accreting TDs is lower than for optically thick disks (40%-45%
versus 77%-79%, respectively). We confirm our previous result that the
accreting TDs have a median accretion rate similar to normal optically
thick disks. We confirm that two star formation modes (isolated versus
clustered) exist in L1641. We find that the diskless YSOs are
statistically older than the YSOs with optically thick disks and the
TD objects have a median age that is intermediate between those of the
other two populations. We tentatively study the star formation history
in L1641 based on the age distribution and find that star formation
started to be active 2-3 Myr ago.
Description:
We combine newly obtained spectroscopic data from Hectospec and
Hectochelle with photometric data from Paper I (Fang et al., 2009,
Cat. J/A+A/504/461).
The intermediate-resolution spectra of sources were taken with the
Hectospec multi-object spectrograph in the range 3700-9000Å with a
resolution of ∼5Å. The observational data were taken on the nights
of 2011 January 23, 24, and 25.
The high-resolution Hα spectroscopy of sources was obtained with
the Hectochelle multi-object spectrograph which can take a maximum of
240 spectra simultaneously with a spectral resolution of 34000. We
used the OB 26 filter which simultaneously covers Hα emission
line and the Li I(6708) absorption line. The observational data were
taken on the night of 2010 February 5 with two pointings.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 140 1388 The optical and near-infrared photometric
magnitudes of the YSOs in L1641
table3.dat 156 1388 The infrared photometric magnitudes of the YSOs
in L1641
table4.dat 84 623 Stellar and disk properties of the YSOs in L1641
table5.dat 178 617 Stellar masses and ages of the YSOs
table6.dat 71 452 Accretion properties of the YSOs in L1641 from
Hectochelle
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See also:
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/ApJ/746/154 : Sco-Cen members spectroscopy (Pecaut+, 2012)
J/A+A/533/A109 : Pisa pre-main sequence tracks and isochrones (Tognelli+, 2011)
J/A+A/504/461 : Paper I. YSOs in L1630N and L1641 (Fang+, 2009)
J/A+A/489/1409 : Infrared photometry and spectroscopy in L1641N (Galfalk+ 2008)
J/A+A/337/403 : Low-mass stars evolutionary models (Baraffe+ 1998)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq [1/1388] Running sequence number
6- 7 I2 h RAh [5] Hour of Right Ascension (J2000)
9- 10 I2 min RAm [34/43] Minute of Right Ascension (J2000)
12- 16 F5.2 s RAs Second of Right Ascension (J2000)
18 A1 --- DE- [-] Sign of the Declination (J2000)
19- 20 I2 deg DEd [6/9] Degree of Declination (J2000)
22- 23 I2 arcmin DEm Arcminute of Declination (J2000)
25- 28 F4.1 arcsec DEs Arcsecond of Declination (J2000)
30- 34 F5.2 mag u'mag ? SDSS u' band magnitude (1)
36- 39 F4.2 mag e_u'mag ? Uncertainty in u'mag
41- 45 F5.2 mag g'mag ? SDSS g' band magnitude (1)
47- 50 F4.2 mag e_g'mag ? Uncertainty in g'mag
52- 56 F5.2 mag r'mag ? SDSS r' band magnitude (1)
58- 61 F4.2 mag e_r'mag ? Uncertainty in r'mag
63- 67 F5.2 mag i'mag ? SDSS i' band magnitude (1)
69- 72 F4.2 mag e_i'mag ? Uncertainty in i'mag
74- 78 F5.2 mag z'mag ? SDSS z' band magnitude (1)
80- 83 F4.2 mag e_z'mag ? Uncertainty in z'mag
85- 89 A5 --- INS1 Instrument used to obtain ugriz photometry (1)
91- 95 F5.2 mag Jmag [8.08/17.51]? UKIDSS J band magnitude
97-100 F4.2 mag e_Jmag [0.01/0.32]? Uncertainty in Jmag
102-106 F5.2 mag Hmag ? UKIDSS H band magnitude
108-111 F4.2 mag e_Hmag ? Uncertainty in Hmag
113-117 F5.2 mag Ksmag [5.15/17.93]? UKIDSS Ks band magnitude
119-122 F4.2 mag e_Ksmag [0.01/0.29]? Uncertainty in Ksmag
124-129 A6 --- INS2 Instrument used to obtain JHK photometry (2)
131-134 F4.1 mag Av ? The V band extinction
136 A1 --- Sp? [N/Y] Observed with spectroscopy? (N=No)
138 A1 --- IR? [N/Y/?] Shows IR excess emission? (?=Unknown)
140 A1 --- X? [N/Y] Has X-ray emission? (Y=Yes)
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Note (1): the SDSS survey does not cover the south-east helf of the L1641
cloud; CCD imaging was done with the Sloan filters in this region.
SDSS = Sloan Digital Sky Survey;
LAICA = Large Area Imager for Calar Alto (Calar Alto 3.5m telescope).
Note (2): JHKs photometry obtained from:
2MASS = Two-Micron All Sky Survey;
UKIDSS = UKIRT infrared deep sky survey.
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq [1/1388] Running sequence number
6- 7 I2 h RAh Hour of Right Ascension (J2000)
9- 10 I2 min RAm Minute of Right Ascension (J2000)
12- 16 F5.2 s RAs Second of Right Ascension (J2000)
18 A1 --- DE- Sign of the Declination (J2000)
19- 20 I2 deg DEd Degree of Declination (J2000)
22- 23 I2 arcmin DEm Arcminute of Declination (J2000)
25- 28 F4.1 arcsec DEs Arcsecond of Declination (J2000)
30- 34 F5.2 mag W1mag [3.66/18.11]? WISE 3.4 micron band magnitude
36- 39 F4.2 mag e_W1mag [0.02/0.45]? Uncertainty in W1mag
41- 45 F5.2 mag W2mag ? WISE 4.6 micron band magnitude
47- 50 F4.2 mag e_W2mag ? Uncertainty in W2mag
52- 56 F5.2 mag W3mag ? WISE 12 micron band magnitude
58- 61 F4.2 mag e_W3mag ? Uncertainty in W3mag
63- 67 F5.2 mag W4mag [-2.49/9.18]? WISE 22 micron band magnitude
69- 72 F4.2 mag e_W4mag [0.01/0.54]? Uncertainty in W4mag
74- 78 F5.2 mag [3.6] [5.43/18.46]? Spitzer/IRAC 3.6um band magnitude
80- 83 F4.2 mag e_[3.6] [0.06/0.5]? Uncertainty in [3.6]
85- 89 F5.2 mag [4.5] ? Spitzer/IRAC 4.5 micron band magnitude
91- 94 F4.2 mag e_[4.5] ? Uncertainty in [4.5]
96-100 F5.2 mag [5.8] ? Spitzer/IRAC 5.8 micron band magnitude
102-105 F4.2 mag e_[5.8] ? Uncertainty in [5.8]
107-111 F5.2 mag [8.0] [2.73/14.25]? Spitzer/IRAC 8.0um band magnitude
113-116 F4.2 mag e_[8.0] [0.06/0.65]? Uncertainty in [8.0]
118-122 F5.2 mag [24] [-2.13/9.96]? Spitzer/MIPS 24um band magnitude
124-127 F4.2 mag e_[24] [0.06/0.34]? Uncertainty in [24]
129-133 F5.2 --- a2-8 [-2.87/4.39]? Spectral slope 2/8um (3)
135-139 F5.2 --- a2-24 [-3.16/2.02]? Spectral slope 2/24um (3)
141-145 F5.2 --- a3.6-8 [-3.36/3.35]? Spectral slope 3.6/8um (3)
147-151 F5.2 --- a3.6-24 [-3.31/2.83]? Spectral slope 3.6/24um (3)
153-156 A4 --- Class Classification: DD(=debris disk candidate),
Flat, I, II, III, TD(=Transition Disk), or TD?
--------------------------------------------------------------------------------
Note (3): the spectral slope is defined as
α=dlog(λFλ)/dlog(λ)
computed from the dereddened photometry.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq [1/1388] Running sequence number
6- 7 I2 h RAh Hour of Right Ascension (J2000)
9- 10 I2 min RAm Minute of Right Ascension (J2000)
12- 16 F5.2 s RAs Second of Right Ascension (J2000)
18 A1 --- DE- Sign of the Declination (J2000)
19- 20 I2 deg DEd Degree of Declination (J2000)
22- 23 I2 arcmin DEm Arcminute of Declination (J2000)
25- 28 F4.1 arcsec DEs Arcsecond of Declination (J2000)
30- 33 A4 --- SpT MK spectral type
35- 41 F7.3 Lsun L [0.005/448.72] Luminosity
43- 45 F3.1 mag Av [0/9.8] The V band extinction
47- 52 F6.1 0.1nm EWHa [-407/2.6]? Hα equivalent width in Å
54- 58 F5.1 0.1nm EWHb [-87/69]? Hβ equivalent width in Å
60 A1 --- l_logMHa Limit flag on logMHa
62- 67 F6.1 [Msun/yr] logMHa [-12/-5]? Log mass accretion rate from Hα
69 A1 --- l_logMHb Limit flag on logMHb
71- 76 F6.1 [Msun/yr] logMHb ? Log mass accretion rate from Hβ
78 A1 --- TTS [C/W] T Tauri star type (C=Classical, or W=Weak)
80- 84 A5 --- Disk Disk type (1)
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Note (1): Disk type as follows:
N = diskless star;
Thick = optically-thick disk (α3.6-8 ≥ -1.8);
Thin = optically-thin disk (-2.5 ≤ α3.6-8 < -1.8);
TD = transition disk;
DD = debris disk candidate.
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq [1/1388] Running sequence number
6- 7 I2 h RAh Hour of Right Ascension (J2000)
9- 10 I2 min RAm Minute of Right Ascension (J2000)
12- 16 F5.2 s RAs Second of Right Ascension (J2000)
18 A1 --- DE- Sign of the Declination (J2000)
19- 20 I2 deg DEd Degree of Declination (J2000)
22- 23 I2 arcmin DEm Arcminute of Declination (J2000)
25- 28 F4.1 arcsec DEs Arcsecond of Declination (J2000)
30- 33 F4.2 Msun M1 [0.1/4.5]? Mass from D08 (1)
35- 38 F4.2 Msun e_M1 [0/0.83]? Lower limit uncertainty in M1
40- 43 F4.2 Msun E_M1 [0/0.63]? Upper limit uncertainty in M1
45- 48 F4.1 Myr Age1 [0/66]? Age from D08 (1)
50- 53 F4.1 Myr e_Age1 [0/49.6]? Lower limit uncertainty in Age1
55- 58 F4.1 Myr E_Age1 [0/36.9]? Upper limit uncertainty in Age1
60- 63 F4.2 Msun M2 [0.1/3.7]? Mass from S00 (1)
65- 68 F4.2 Msun e_M2 ? Lower limit uncertainty in M2
70- 73 F4.2 Msun E_M2 ? Upper limit uncertainty in M2
75- 78 F4.1 Myr Age2 [0.1/72]? Age from S00 (1)
80- 83 F4.1 Myr e_Age2 ? Lower limit uncertainty in Age2
85- 88 F4.1 Myr E_Age2 ? Upper limit uncertainty in Age2
90- 93 F4.2 Msun M3 [0.05/1.4]? Mass from B98 (1)
95- 98 F4.2 Msun e_M3 ? Lower limit uncertainty in M3
100-103 F4.2 Msun E_M3 ? Upper limit uncertainty in M3
105-108 F4.1 Myr Age3 [1/43.1]? Age from B98 (1)
110-113 F4.1 Myr e_Age3 ? Lower limit uncertainty in Age3
115-118 F4.1 Myr E_Age3 ? Upper limit uncertainty in Age3
120-123 F4.2 Msun M4 [0.06/2.9]? Mass from DM97 (1)
125-128 F4.2 Msun e_M4 ? Lower limit uncertainty in M4
130-133 F4.2 Msun E_M4 ? Upper limit uncertainty in M4
135-138 F4.1 Myr Age4 [0/74.8]? Age from DM97 (1)
140-143 F4.1 Myr e_Age4 ? Lower limit uncertainty in Age4
145-148 F4.1 Myr E_Age4 ? Upper limit uncertainty in Age4
150-153 F4.2 Msun M5 [0.2/4.7]? Mass from Pisa11 (1)
155-158 F4.2 Msun e_M5 ? Lower limit uncertainty in M5
160-163 F4.2 Msun E_M5 ? Upper limit uncertainty in M5
165-168 F4.1 Myr Age5 [0.2/56.1]? Age from Pisa11 (1)
170-173 F4.1 Myr e_Age5 ? Lower limit uncertainty in Age5
175-178 F4.1 Myr E_Age5 ? Upper limit uncertainty in Age5
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Note (1): References as below:
D08 = Dotter et al. 2008ApJS..178...89D 2008ApJS..178...89D
S00 = Siess et al. 2000A&A...358..593S 2000A&A...358..593S
B98 = Baraffe et al., 1998, Cat. J/A+A/337/403
DM97 = D'Antona & Mazzitelli 1997MmSAI..68..807D 1997MmSAI..68..807D
Pisa11 = Tognelli et al., 2011, Cat. J/A+A/533/A109
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Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq [1/1211] Running sequence number
6- 7 I2 h RAh Hour of Right Ascension (J2000)
9- 10 I2 min RAm Minute of Right Ascension (J2000)
12- 16 F5.2 s RAs Second of Right Ascension (J2000)
18 A1 --- DE- Sign of the Declination (J2000)
19- 20 I2 deg DEd Degree of Declination (J2000)
22- 23 I2 arcmin DEm Arcminute of Declination (J2000)
25- 28 F4.1 arcsec DEs Arcsecond of Declination (J2000)
30- 33 F4.2 0.1nm EWLi [0.18/0.8]? Li I equivalent width in Å
35- 40 F6.1 0.1nm EWHa [-228.7/0.4]? Hα equivalent width;
in units of Angstroms
42- 44 I3 km/s FWHa.1 [27/612]? Hα full width at 10% peak
intensity
46 A1 --- TTS [C/W] T Tauri type (C=classical or W=weak)
48- 50 I3 % Prob [0/100]? Accretor probability
52 A1 --- l_logMac Limit flag on logMac
54- 59 F6.1 [Msun/yr] logMac [-12.2/-7]? Log of mass accretion rate
61- 71 A11 "YYYY/MMM/DD" Date Date of the observation
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History:
From electronic version of the journal
References:
Fang et al. Paper I. 2009A&A...504..461F 2009A&A...504..461F Cat. J/A+A/504/461
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 08-Aug-2013