J/AJ/159/200 Young stellar objects in Lupus star-forming region (Melton, 2020)
A Random Forest approach to identifying young stellar object candidates in the
Lupus star-forming region.
Melton E.
<Astron. J., 159, 200 (2020)>
=2020AJ....159..200M 2020AJ....159..200M
ADC_Keywords: Star Forming Region; Spectral types; Proper motions;
Parallaxes, trigonometric; Photometry, infrared; YSOs
Keywords: T associations ; Moving clusters ; Young star clusters ;
Random Forests
Abstract:
The identification and characterization of stellar members within a
star-forming region are critical to many aspects of star formation,
including formalization of the initial mass function, circumstellar
disk evolution, and star formation history. Previous surveys of the
Lupus star-forming region have identified members through infrared
excess and accretion signatures. We use machine learning to identify
new candidate members of Lupus based on surveys from two space-based
observatories: ESA's Gaia and NASA's Spitzer. Astrometric measurements
from Gaia's Data Release 2 and astrometric and photometric data from
the Infrared Array Camera on the Spitzer Space Telescope, as well as
from other surveys, are compiled into a catalog for the random forest
(RF) classifier. The RF classifiers are tested to find the best
features, membership list, non-membership identification scheme,
imputation method, training set class weighting, and method of dealing
with class imbalance within the data. We list 27 candidate members of
the Lupus star-forming region for spectroscopic follow-up. Most of the
candidates lie in Clouds V and VI, where only one confirmed member of
Lupus was previously known. These clouds likely represent a slightly
older population of star formation.
Description:
A source list of objects toward the Lupus star-forming region is
constructed from archived Infrared Array Camera (IRAC) images in the
Spitzer Heritage Archive. These images span a range of over 10yr and
cover five distinct regions of the Lupus star-forming region,
providing coverage over Lupus Clouds I, III-VI. Between 2004 and 2014,
the IRAC instrument on Spitzer imaged the Lupus star-forming region.
Forty-four observing runs were performed in 2004, one observing run in
2006, 12 in 2007, four in 2008, and two in 2011 (see Table 2).
We include Gaia data in our analysis to further refine candidate
selection. The Gaia mission second data release contains proper motion
measurements of sources, parallax measurements, and optical broadband
photometry (G), covering 0.330-1.050µm (see I/345).
J, H, and Ks band photometry from the Two Micron All Sky Survey
(2MASS) and i, J, and Ks band photometry from the Deep Near-Infrared
Survey of the southern sky (DENIS) are incorporated by matching the
source list to the photometric catalogs. The J filters from 2MASS and
DENIS are treated as the same bandpass and combined, as are the Ks
filters. We remove 2MASS and DENIS photometry data from the on-cloud
catalog with errors above 0.1mag.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 42 97 IRAC epochs of Lupus
table4.dat 127 173 Literature search results for previously identified
spectroscopic members
table5.dat 171 173 Previously identified member catalog information
table9.dat 106 27 Astrometry information for the candidates
identified by the highest ranked Random Forest
classifier with a probability threshold of 0.4180
table10.dat 83 27 Photometry information for the candidates
identified by the highest ranked Random Forest
classifier with a probability threshold of 0.4180
table13.dat 167 404 Extended candidate catalog information
--------------------------------------------------------------------------------
See also:
II/240 : The DENIS database first release (Epchtein+, 1999)
II/332 : c2d Spitzer final data release (DR4) (Evans+, 2003)
VII/244 : Atlas and Catalog of Dark Clouds (Dobashi+, 2005)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/360 : Gaia DR2 x AllWISE catalogue (Marton+, 2019)
J/A+AS/85/915 : Walraven Photo. of southern OB associations (de Geus+, 1990)
J/A+AS/123/329 : New weak-line T Tauri stars in Lupus (Krautter+ 1997)
J/MNRAS/313/43 : OB association members in ACT+TRC Catalogs (Hoogerwerf,2000)
J/A+A/356/541 : T Tauri stars in the Sco-Cen OB association (Koehler+, 2000)
J/AJ/124/1670 : Post-T Tauri Stars in Sco-Cen Association (Mamajek+, 2002)
J/A+A/454/595 : X-ray emission of T Tau stars in Lupus 3 (Gondoin, 2006)
J/ApJ/662/413 : 2MASS survey wide multiplicity 3 associations (Kraus+, 2007)
J/ApJ/658/480 : Pre-main-sequence stars in Lupus association (Makarov+,2007)
J/ApJS/177/551 : Spitzer c2d survey of Lupus dark clouds (Merin+, 2008)
J/A+A/500/1045 : Cool stars and brown dwarfs in Lupus clouds (Comeron+, 2009)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/A+A/529/A108 : Lupus clouds proper motion study with VO (Lopez Marti+,2011)
J/ApJ/756/133 : ScoCen debris disks around B- and A-type stars (Chen+, 2012)
J/MNRAS/427/3280 : Ultra-cool dwarfs at low Galactic latitudes (Folkes+, 2012)
J/AJ/144/8 : Spectro. of ∼100 G/K/M-type Sco-Cen members (Song+, 2012)
J/A+A/561/A2 : 36 acreting YSOs emission lines (Alcala+, 2014)
J/ApJ/785/159 : SONYC census of substellar objects in Lupus 3 (Muzic+, 2014)
J/ApJS/220/11 : SEDs of Spitzer YSOs in the Gould Belt (Dunham+, 2015)
J/MNRAS/461/794 : Scorpius-Centaurus K-Type Stars (Pecaut+, 2016)
J/A+A/600/A20 : Lupus YSOs X-shooter spectroscopy (Alcala+, 2017)
J/AJ/154/134 : Planetary-mass brown dwarfs in the Taurus SFR (Esplin+,2017)
J/AJ/154/46 : Proper motions & photo. for members of Cha I (Esplin+, 2017)
J/ApJ/838/150 : The Taurus-Auriga ecosystem. I. (Kraus+, 2017)
J/A+A/619/A52 : Dense cores and YSOs in Lupus complex (Benedettini+, 2018)
J/AJ/156/271 : The stellar membership of the Taurus SFR (Luhman, 2018)
J/A+A/609/A116 : Low extinction TGAS HR Catalogue (Ruiz-Dern+, 2018)
http://sha.ipac.caltech.edu/applications/Spitzer/SHA/ : Spitzer Herit. Archive
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- AOR [3652608/51016704] Spitzer/IRAC
Astronomical Observing Request ID
10- 14 I5 --- PID [6/90071] Program ID
16- 29 A14 --- PI Principal Investigator
31- 42 F12.7 yr Epoch [2004/2015] Mean Observation Date in decimal years
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- ID Number ID of the previously confirmed member
6- 29 A24 --- SName Identifier for source from a match to
the SIMBAD database
31- 45 A15 --- SpType Spectral Type from literature search
47- 58 A12 --- r_SpType References for spectral type (1)
60-127 A68 --- Class Lada Class and reference(s) in parenthesis (codes
are the same as SpType references)
--------------------------------------------------------------------------------
Note (1): References as follows:
1 = Hughes+, 1994AJ....108.1071H 1994AJ....108.1071H
2 = Krautter+, 1997, J/A+AS/123/329
3 = Comeron+, 2003A&A...406.1001C 2003A&A...406.1001C
4 = Allen+, 2007ApJ...655.1095A 2007ApJ...655.1095A
5 = Merin+, 2008, J/ApJS/177/551
6 = Mortier+, 2011MNRAS.418.1194M 2011MNRAS.418.1194M
7 = Comeron+, 2013A&A...554A..86C 2013A&A...554A..86C
8 = Alcala+, 2014, J/A+A/561/A2
9 = Muzic+, 2014, J/ApJ/785/159
10 = Dunham+, 2015, J/ApJS/220/11
11 = Alcala+, 2017, J/A+A/600/A20
12 = This work
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- ID Number ID of the previously confirmed member
6- 7 I2 h RAh [15/16] 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- 18 A1 --- DE- [-] Sign of Declination (J2000)
19- 20 I2 deg DEd [33/42] Degree of Declination (J2000)
22- 23 I2 arcmin DEm Arcminute of Declination (J2000)
25- 28 F4.1 arcsec DEs Arcsecond of Declination (J2000)
30- 35 F6.2 mas/yr pmRA-I [-22/8]? Proper motion in the right ascension
measured with IRAC
37- 40 F4.2 mas/yr e_pmRA-I [0.04/6.3]? Error in pmRA-I
42- 47 F6.2 mas/yr pmDE-I [-34/2]? Proper motion in the declination
measured with IRAC
49- 53 F5.2 mas/yr e_pmDE-I [0.01/11.3]? Error in pmDE-I
55- 60 F6.2 mas/yr pmRA-G [-31/3]? Proper motion in the right ascension
from Gaia
62- 65 F4.2 mas/yr e_pmRA-G [0.06/4]? Error in pmRA-G
67- 72 F6.2 mas/yr pmDE-G [-38/3]? Proper motion in the declination from
Gaia
74- 77 F4.2 mas/yr e_pmDE-G [0.04/1.8]? Error in pmDE-G
79- 82 F4.2 mas plx [1.5/9.1]? Gaia DR2 Parallax measurement
84- 87 F4.2 mas e_plx [0.03/0.61]? Error in plx
89- 93 F5.2 mag Gmag [6.61/19.22]? Gaia DR2 G magnitude
95- 99 F5.2 mag imag [8.58/16.47]? DENIS i magnitude
101-104 F4.2 mag e_imag [0.02/0.1]? Error in the DENIS i magnitude
106-110 F5.2 mag Jmag [5.88/15.6]? Combined J magnitude from DENIS
and 2MASS
112-115 F4.2 mag e_Jmag [0.02/0.1]? Error in Jmag
117-121 F5.2 mag Hmag [5.2/14.87]? 2MASS H magnitude
123-126 F4.2 mag e_Hmag [0.02/0.09]? Error in Hmag
128-132 F5.2 mag Ksmag [4.33/14.38]? Combined Ks magnitude from DENIS
and 2MASS
134-137 F4.2 mag e_Ksmag [0.01/0.08]? Error in Ksmag
139-143 F5.2 mag [3.6] [8.68/14.03]? Spitzer/IRAC [3.6] magnitude
145-148 F4.2 mag e_[3.6] [0.13/0.13]? Error in [3.6] magnitude
150-154 F5.2 mag [4.5] [6.24/13.95]? Spitzer/IRAC [4.5] magnitude
156-159 F4.2 mag e_[4.5] [0.13/0.17]? Error in [4.5] magnitude
161-166 F6.4 --- Memb [0/0.885] Probability of Membership to the
Lupus star-forming region from the Random
Forest classifier
168-171 A4 --- Notes ? Notes indicating if the member was removed
from the member list or not included in the
constrained member list (2)
--------------------------------------------------------------------------------
Note (2): Notes as follows:
rm. = sources that were not included in the training set;
con. = sources not included in the constrained member training set.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table9.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 -- Seq [1/27] Number ID of the candidate member
4- 5 I2 h RAh [15/16] Hour of Right Ascension (J2000)
7- 8 I2 min RAm Minute of Right Ascension (J2000)
10- 14 F5.2 s RAs Second of Right Ascension (J2000)
16- 16 A1 --- DE- [-] Sign of Declination (J2000)
17- 18 I2 deg DEd [33/42] Degree of Declination (J2000)
20- 21 I2 arcmin DEm Arcminute of Declination (J2000)
23- 27 F5.2 arcsec DEs Arcsecond of Declination (J2000)
29- 33 F5.1 mas/yr pmRA-I [-47/-2]? Proper motion in the right ascension
measured with IRAC
35- 37 F3.1 mas/yr e_pmRA-I [0.4/7]? Error in pmRA-I
39- 43 F5.1 mas/yr pmDE-I [-58/-14]? Proper motion in the declination
measured with IRAC
45- 48 F4.1 mas/yr e_pmDE-I [0.2/12]? Error in pmDE-I
50- 55 F6.2 mas/yr pmRA-G [-50/-8.7] Proper motion in the right ascension
measured with Gaia
57- 60 F4.2 mas/yr e_pmRA-G [0.08/1.1] Error in pmRA-G
62- 67 F6.2 mas/yr pmDE-G [-61/-19] Proper motion in the declination
measured with Gaia
69- 72 F4.2 mas/yr e_pmDE-G [0.05/0.7] Error in pmDE-G
74- 77 F4.2 mas plx [4.37/9.24] Gaia DR2 parallax measurement
79- 82 F4.2 mas e_plx [0.04/0.5] Error in the parallax
84-106 A23 -- SName ? SIMBAD Name
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table10.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/27] Number ID of the candidate member
4- 8 F5.2 mag Gmag [12.9/19.3] Gaia DR2 G magnitude
10- 14 F5.2 mag imag [12.26/16.27]? DENIS i magnitude
16- 19 F4.2 mag e_imag [0.02/0.07]? Error in the DENIS i magnitude
21- 25 F5.2 mag Jmag [10.33/15.57] Combined J magnitude from DENIS and
2MASS
27- 30 F4.2 mag e_Jmag [0.02/0.06] Error in the combined J magnitude from
DENIS and 2MASS
32- 36 F5.2 mag Hmag [9.73/15.07] 2MASS H magnitude
38- 41 F4.2 mag e_Hmag [0.02/0.09] Error in the 2MASS H magnitude
43- 47 F5.2 mag Ksmag [9.48/14.7] Combined Ks magnitude from DENIS and
2MASS
49- 52 F4.2 mag e_Ksmag [0.02/0.08] Error in Ksmag
54- 58 F5.2 mag [3.6] [9.2/14.3] Spitzer/IRAC [3.6] magnitude
60- 63 F4.2 mag e_[3.6] [0.13/0.14] Error in the IRAC [3.6] magnitude
65- 69 F5.2 mag [4.5] [9.2/14.2] Spitzer/IRAC [4.5] magnitude
71- 74 F4.2 mag e_[4.5] [0.1/0.3] Error in the IRAC [4.5] magnitude
76- 81 F6.4 --- Memb [0.4/0.7] Probability of Membership to the
Lupus star-forming region from the Random Forest
classifier
83- 83 A1 --- Disk? Indicator of the presence of a disk (Y=Yes
--4 occurrences) or not (N) as determined by
the analysis in Section 7.3 of the paper
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table13.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- ID Number ID of the previously confirmed member
8- 9 I2 h RAh [15/16] Hour of Right Ascension (J2000)
11- 12 I2 min RAm Minute of Right Ascension (J2000)
14- 18 F5.2 s RAs Second of Right Ascension (J2000)
20- 20 A1 --- DE- [-] Sign of Declination (J2000)
21- 22 I2 deg DEd [32/42] Degree of Declination (J2000)
24- 25 I2 arcmin DEm Arcminute of Declination (J2000)
27- 30 F4.1 arcsec DEs Arcsecond of Declination (J2000)
32- 38 F7.2 mas/yr pmRA-G [-160/67] Proper motion in the right ascension
from Gaia
40- 43 F4.2 mas/yr e_pmRA-G [0.05/1.5] Error in pmRA-G
45- 51 F7.2 mas/yr pmDE-G [-277/46] Proper motion in the declination from
Gaia
53- 56 F4.2 mas/yr e_pmDE-G [0.03/1] Error in pmDE-G
58- 61 F4.2 mas plx [5.5/7.5] Gaia DR2 parallax measurement
63- 66 F4.2 mas e_plx [0.02/0.7] Error in parallax
68- 72 F5.2 mag Gmag [6.73/19.93] Gaia DR2 G magnitude
74- 78 F5.2 mag imag [8.42/17.01]? DENIS i magnitude from DENIS
80- 83 F4.2 mag e_imag [0.02/0.09]? Error in the DENIS i magnitude
85- 89 F5.2 mag Jmag [5.29/16.13]? Combined J magnitude from DENIS
and 2MASS
91- 94 F4.2 mag e_Jmag [0.02/0.08]? Error in Jmag
96-100 F5.2 mag Hmag [5.01/15.39]? 2MASS H magnitude
102-105 F4.2 mag e_Hmag [0.02/0.09]? Error in the 2MASS H magnitude
107-111 F5.2 mag Ksmag [4.55/14.64]? Combined Ks magnitude from DENIS
and 2MASS
113-116 F4.2 mag e_Ksmag [0.02/0.1]? Error in Ksmag
118-123 F6.4 --- Memb [0.44/0.84] Probability of Membership to the
Lupus star-forming region from the Random
Forest classifier
125-125 A1 --- Label Label indicating Extended Candidate Group (1)
127-143 A17 --- Flag Quality(s) for which the source is discrepant
with members (2)
145-167 A23 --- SName Simbad Identifier
--------------------------------------------------------------------------------
Note (1): Labels as follows:
u = candidate with a RF-Prob above our upper threshold of 0.5025
l = candidate with a RF-Prob above our lower threshold of 0.4475 and
below 0.5025
Note (2): Indicates any qualities that may lie outside those of the previously
identified members of Lupus. Flags as follows:
pm = proper motion is greater than 3σ outside the multi-variate
gaussian fits to the member proper motions
G.K = the position is below and to the left of the lower boundary of the
members in the K vs G-K color-magnitude diagram
i.K = the position is below and to the left of the lower boundary of the
members in the K vs i-K color-magnitude diagram
H.K = the position is below and to the left of the lower boundary of the
members in the K vs H-K color-magnitude diagram
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History:
From electronic version of the journal
29-Jun-2020: Insert into VizieR
30-Sep-2022: Multiple issues in coordinates of table5. Replaced by
coordinates from SIMBAD
(End) Prepared by [AAS], Coralie Fix [CDS], 29-May-2020