J/AJ/168/63 Candidate YSOs from JWST ERO obs. of NGC 3324 (Crompvoets+, 2024)
Climbing the Cliffs: classifying young stellar objects in the Cosmic Cliffs JWST
data using a probabilistic random forest.
Crompvoets B.L., Di Francesco J., Teimoorinia H., Preibisch T.
<Astron. J., 168, 63 (2024)>
=2024AJ....168...63C 2024AJ....168...63C
ADC_Keywords: Photometry, infrared; YSOs; Star Forming Region
Keywords: Star formation ; Star forming regions ; Random Forests ;
Classification ; Young stellar objects
Abstract:
Among the first observations released to the public from the JWST was
a section of the star-forming region NGC 3324 known colloquially as
the "Cosmic Cliffs." We build a photometric catalog of the region and
test the ability of using the probabilistic random forest
machine-learning method to identify its young stellar objects (YSOs).
We find 450 candidate YSOs (cYSOs) out of 19497 total objects within
the field, 413 of which are cYSOs not found in previous works. These
classifications are verified with several different metrics, including
recall and precision. Using the obtained probabilities of objects
being YSOs, we employ a Monte Carlo approach to determine the surface
density of cYSOs in the Cosmic Cliffs, which we find to be largely
coincident with column densities derived from Herschel data, up to a
column density of 1.37x1022cm-2. The newly determined number and
spatial distribution of YSOs in the Cosmic Cliffs demonstrate that
JWST is far more capable of detecting YSOs in dusty regions than
Spitzer. Comparisons of the observed colors and brightness of faint
cYSOs with those of pre-main-sequence models suggest JWST has detected
a significant population of substellar YSOs in the Cosmic Cliffs. The
size of this population further suggests previous estimates of star
formation efficiencies in molecular clouds have been systematically
low.
Description:
The JWST Early Release Observations (ERO) of NGC 3324 focused on the
Cosmic Cliffs, a ∼7.4'x4.4' area with NIRCam, and a ∼6.4'x2.2' area
within the NIRCam field with MIRI, all located on the edge of the
Gum31 bubble. The data were collected in six NIRCam bands and four
MIRI bands. We will focus on the NIRCam data for this paper.
See Section 2.3.
We used pipeline-generated JWST images of the Cosmic Cliffs fields
that were made publicly available as FITS files by MAST. The specific
data analyzed in this work can be accessed via DOI:10.17909/bsbn-3m50.
We did not use the photometric data also provided by MAST.
See Section 3.2.
From our photometry of the JWST Cosmic Cliffs field, we retrieve a
total of 19497 objects. Of these, 450 are candidate YSOs (cYSOs),
i.e., have a probability greater than 50% of being so based on the PRF
model with all bands included, as well as in four out of six tests
where in each test the data from one filter are excluded.
See Section 4.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
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10 37 21.83 -58 36 54.0 NGC 3324 = OCl 819
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 470 19497 Fluxes, J2000 coordinates, and probabilities
for sources classified as candidate YSOs
table4.dat 66 36 Candidate YSOs from other works matched to
our candidate YSOs
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See also:
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/ApJS/194/4 : Classification of CCCP X-ray sources (Broos+, 2011)
J/A+A/539/A143 : Nearby B-stars stellar param. and abundances (Nieva+, 2012)
J/A+A/549/A67 : Embedded YSOs in Carina Nebula complex (Gaczkowski+, 2013)
J/ApJS/209/31 : The MYStIX IR-Excess Source catalog (MIRES) (Povich+, 2013)
J/A+A/564/A120 : Chandra X-ray observation of Gum 31 (Preibisch+, 2014)
J/ApJS/220/11 : SEDs of Spitzer YSOs in the Gould Belt (Dunham+, 2015)
J/A+A/647/A116 : YSO candidate catalog from ANN (Cornu+, 2021)
J/MNRAS/507/5106 : NGC 6822 massive young stellar objects (Kinson+, 2021)
J/ApJS/254/33 : Gal. midplane Spitzer/IRAC cand. YSOs (SPICY) (Kuhn+, 2021)
J/A+A/660/A11 : Gaia distances to the Carina Nebula Complex (Goeppl+, 2022)
J/MNRAS/517/140 : M33 massive young stellar objects (Kinson+, 2022)
J/AJ/165/3 : SPICY. II. Spectroscopic obs. of 26 YSOs (Kuhn+, 2023)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- Seq [0/19496] Sequential object index
7- 14 F8.4 deg RAdeg [159.1/159.31] Right Ascension (J2000)
16- 23 F8.4 deg DEdeg [-58.7/-58.5] Declination (J2000)
25- 33 F9.3 pix xpix [76/14179] X pixel on image (s)
35- 42 F8.3 pix ypix [65/8373] Y pixel on image (s)
44- 48 F5.2 mag F090W [12.9/28.55]? Flux density in JWST/NIRCam
F090W band, Vega magnitudes
50- 54 F5.2 mag F187N [10/25.01]? Flux density in JWST/NIRCam
F187N band, Vega magnitudes
56- 60 F5.2 mag F200W [10.5/26.16]? Flux density in JWST/NIRCam
F200W band, Vega magnitudes
62- 66 F5.2 mag F335M [8.15/22.1]? Flux density in JWST/NIRCam
F335M band, Vega magnitudes
68- 72 F5.2 mag F444W [7.7/22.75]? Flux density in JWST/NIRCam
F444W band, Vega magnitudes
74- 78 F5.2 mag F470N [6.7/22.56]? Flux density in JWST/NIRCam
F470N band, Vega magnitudes
80- 83 F4.2 mag e_F090W [0.01/0.6]? Uncertainty in F090W
85- 88 F4.2 mag e_F187N [0.01/0.6]? Uncertainty in F187N
90- 93 F4.2 mag e_F200W [0/0.4]? Uncertainty in F200W
95- 98 F4.2 mag e_F335M [0.01/0.6]? Uncertainty in F335M
100- 103 F4.2 mag e_F444W [0/0.6]? Uncertainty in F444W
105- 108 F4.2 mag e_F470N [0/0.6]? Uncertainty in F470N
110- 135 A26 --- Survey Prior Survey detection (1)
137- 140 I4 --- SPICY [7423/7481]? SPICY identifier if detected
in Kuhn+ 2021, J/ApJS/254/33
142 I1 --- ClInit [0/1]? Initial YSO classification
(0=YSO; or 1=contaminant)
144- 165 A22 --- PPRFf090w Probability of being a YSO based on the PRF
model, when the F090W band data are
excluded
167- 186 F20.16 --- PRFf090w [0/1]?=-99.999 Probability of being a YSO
based on the RF model, when the F090W band
data are excluded
188- 205 F18.16 --- PPRFf187n [0.0001/1] Probability of being a YSO based
on the PRF model, when the F187N band data
are excluded
207- 226 F20.16 --- PRFf187n [0/1]?=-99.999 Probability of being a YSO
based on the RF model, when the F187N band
data are excluded
228- 249 A22 --- PPRFf200w Probability of being a YSO based on the PRF
model, when the F200W band data are
excluded
251- 270 F20.16 --- PRFf200w [0/1]?=-99.999 Probability of being a YSO
based on the RF model, when the F200W band
data are excluded
272- 293 A22 --- PPRFf335m Probability of being a YSO based on the PRF
model, when the F335M band data are
excluded
295- 314 F20.16 --- PRFf335m [0/1]?=-99.999 Probability of being a YSO
based on the RF model, when the F335M band
data are excluded
316- 337 A22 --- PPRFf444w Probability of being a YSO based on the PRF
model, when the F444W band data are
excluded
339- 358 F20.16 --- PRFf444w [0/1]?=-99.999 Probability of being a YSO
based on the RF model, when the F444W band
data are excluded
360- 381 A22 --- PPRFf470n Probability of being a YSO based on the PRF
model, when the F470N band data are
excluded
383- 402 F20.16 --- PRFf470n [0/1]?=-99.999 Probability of being a YSO
based on the RF model, when the F470N band
data are excluded
404- 421 F18.16 --- PRFruns [0/1] Fraction of runs where the object is
identified as a YSO based on the PRF method
(2)
423 I1 --- ClPRF [0/1] Final Probabilistic Random Forest YSO
classification (0=YSO; or 1=contaminant)
425- 428 F4.2 --- ProbPRF [0/1] PRF Probability of Class
430- 448 F19.17 --- RFruns [0/1] Fraction of runs where the object is
identified as a YSO based on the RF method
(2)
450- 456 F7.3 --- ClRF [0/1]?=-99.999 Final Regular Random Forest
YSO classification
(0=YSO; or 1=contaminant)
458- 464 F7.3 --- ProbRF [0/1]?=-99.999 RF Probability of Class
466- 470 A5 --- Secure Security of classification as YSO or
contaminant (3)
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Note (1): Prior survey identifications as follows:
IR (Ohlendorf et al. 2013) = Ohlendorf et al. 2013A&A...552A..14O 2013A&A...552A..14O
SPICY (Kuhn et al. 2021) = Kuhn et al. 2021, J/ApJS/254/33
Note (2): A "run" is a set of 100 trials using one model, where the data from
one band are removed. Thus, if RFruns reads 0.166667, then that means
that in only one of the six cases (no data from the F090W band is one
case, no data from the F187N band is another case) was the object
identified as YSO by the RF model.
Note (3): Secure (Section 4) means the source has a probability greater
than 50% of being so based on both the PRF and the RF model with all
bands included, as well as in 4 out of 6 tests where in each test the
data from one filter are excluded, or is otherwise identified as a
contaminant with both the RF and PRF.
"True" = 19420 occurrences.
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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 --- cYSO cYSO position-based name (JHHMMSS.s+DDMMSS)
18- 56 A39 --- Prior Previous Works (1)
58- 61 F4.2 --- Prob [0.01/1]? Probability of the object originally
selected as the cYSO (within 0.0001° of the
position specified in previous works or
matched by eye)
63- 66 F4.2 --- Nearby [0.64/1]? Nearby Probability (2)
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Note (1): The different catalog matches:
OHL*, Ohlendorf et al. 2013A&A...552A..14O 2013A&A...552A..14O;
CXOU, Preibisch et al. 2014, J/A+A/564/A120;
SPICY, Kuhn et al. 2021, J/ApJS/254/33 and
outflow (MHO ####, Reiter et al. 2022MNRAS.517.5382R 2022MNRAS.517.5382R) numbers or
other HH object designations associated with each object are labelled.
Note (2): If "Prob" is less than 50% or not found in at least 4 of 6 runs,
we also check for nearby (within FWHM of original detector) sources of
higher probability due to resolution differences in previous surveys.
The J-2000 designation is marked as the object with greater
probability in these cases.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 25-Sep-2024