J/A+A/663/A133 YSOs toward IRAS 22147+5948 in outer Galaxy (Karska+, 2022)
A census of young stellar objects in two line-of-sight star-forming regions
toward IRAS 22147+5948 in the outer Galaxy.
Karska A., Koprowski M., Solarz A., Szczerba R., Sewilo M., Siodmiak N.,
Elia D., Gawronski M., Grzesiak K., Yung B.H.K., Fischer W.J.,
Kristensen L.E.
<Astron. Astrophys., 663, A133 (2022)>
=2022A&A...663A.133K 2022A&A...663A.133K (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Photometry, infrared ; Photometry, millimetric/submm
Keywords: stars: formation - ISM: molecules - ISM: individual: IRAS 22147+5948
Abstract:
Star formation in the outer Galaxy, namely, outside of the Solar
circle, has not been extensively studied in part due to the low CO
brightness of the molecular clouds linked with the negative
metallicity gradient. Recent infrared surveys provide an overview of
dust emission in large sections of the Galaxy, but they suffer from
cloud confusion and poor spatial resolution at far-infrared
wavelengths.
We aim to develop a methodology to identify and classify young stellar
objects (YSOs) in star-forming regions in the outer Galaxy and use it
to resolve a long-standing disparity in terms of the distance and
evolutionary status of IRAS 22147+5948.
We used a support vector machine learning algorithm to complement
standard color-color and color-magnitude diagrams in our search for
YSOs in the IRAS 22147+5948 region, based on publicly available data
from the Spitzer Mapping of the Outer Galaxy survey. The agglomerative
hierarchical clustering algorithm was used to identify clusters. Then
the physical properties of individual YSOs were calculated. The
distances were determined using CO 1-0 from the Five College Radio
Astronomy Observatory survey.
We identified 13 Class I and 13 Class II YSO candidates using the
color-color diagrams, along with an additional 2 and 21 sources,
respectively, using the applied machine learning techniques. The
spectral energy distributions of 23 sources were modeled with a star
and a passive disk, corresponding to Class II objects. The models of
three sources include envelopes that are typical for Class I objects.
The objects were grouped into two clusters located at a distance of
∼2.2 kpc and 5 clusters at ∼5.6 kpc. The spatial extent of CO, radio
continuum, and dust emission confirms the origin of YSOs in two
distinct star-forming regions along a similar line of sight.
The outer Galaxy may serve as a unique laboratory for exploring star
formation across environments, on the condition that complementary
methods and ancillary data are used to properly account for cloud
confusion and distance uncertainties.
Description:
The SMOG survey and complementary far-IR and CO data allow us to
identify and characterize a population of YSO candidates in the
IRAS 22147+5948 Outer Galaxy region. A combination of standard
color-color diagram method and the machine learning techniques, as
well as information on gas and dust spatial distribution and SED
modeling are necessary to avoid cloud confusion and properly determine
the census of YSOs in specific star forming regions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 72 26 Physical parameters for a subset of YSO Candidates
in the IRAS 22147+5948 region with at least five
photometry points, including one at a wavelength
longer than 12um
tablea1.dat 67 12 Distances to YSOs based on the CO emission and the
Gaia catalog (Bailer-Jones et al.,
2021AJ....161..147B 2021AJ....161..147B, Cat. I/352)
tablea2.dat 54 4 Physical Parameters for a Subset of YSO Candidates
in the IRAS 22147+5948 region with distances from
the Gaia DR3 catalog
tablec1.dat 125 35 Near- and mid-infrared photometry of YSO
candidates in the IRAS 22147+5948 field
tablec2.dat 151 35 Photometry of YSO candidates in the
IRAS 22147+5948 field from mid-infrared to
submillimeter wavelengths
tablec3.dat 130 14 Multi-wavelength photometry of YSO candidates in
the IRAS 22147+5948 field with unknown distances
tablec4.dat 40 24 YSO classification obtained in this work and in
Winston et al. (2019ApJ...880....9W 2019ApJ...880....9W,
Cat. J/ApJ/880/9)
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See also:
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+ 2021)
J/ApJ/880/9 : Spitzer obs. of YSOs in the SMOG field (Winston+, 2019)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1 A1 --- Group [AB] Group (1)
3- 4 I2 --- Seq Sequential number, within the group
6- 22 A17 --- SSTSMOGA IRAC designation SSTSMOGA (GLLL.llll+BB.bbbb)
24 A1 --- n_SSTSMOGA [g] Note on SSTSMOGA (2)
26- 32 A7 --- ModelSet Model set name (G1)
34- 35 A2 --- Classinit YSO class as initially determined using
color-color diagrams and machine learning
algorithms (Sects. 3.2 and 3.3, respectively)
37- 42 A6 --- ClassSED YSO class as determined from the SED fitting
(see Sect. 3.7)
45- 46 A2 --- Select Initial Selection method used in this work are
the color-color/color-magnitude diagrams
(CC; Sect. 3.2) and machine learning
algorithms (ML; Sect. 3.3)
48- 51 F4.1 Rsun R* Stellar radius
53- 57 I5 K T* Stellar temperature
59- 64 F6.1 Lsun L* Stellar luminosity (3)
66- 68 F3.1 Msun M* ?=- Stellar mass (4)
70- 72 F3.1 Myr Age ?=- Stellar age (4)
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Note (1): Group as follows:
A = YSO candidates at ∼5.6kpc
B = YSO candidates at ∼2.2 kpc
Note (2): Note as follows:
g = A more reliable distance for this source is provided by Gaia; see
Appendix A for the SED model adopting the Gaia DR3 distance from
Bailer-Jones et al. (2021AJ....161..147B 2021AJ....161..147B).
Note (3): Stellar luminosities are calculated using the formula
L*=4πR*2σSBT*4, where σSB is the Stefan-Boltzmann
constant.
Note (4): We provide stellar masses (M*) and ages (Age) only for sources with
the most reliable estimates of these parameters (see Sect. 3.7).
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq Sequnetial number
4- 20 A17 --- SSTSMOGA IRAC designation SSTSMOGA (GLLL.llll+BB.bbbb)
22- 31 F10.6 deg RAdeg Right ascension (J2000)
33- 41 F9.6 deg DEdeg Declination (J2000)
43- 46 F4.2 arcsec Sep Separation between the YSO and the closest
Gaia target from the Bailer-Jones et al.
(2021AJ....161..147B 2021AJ....161..147B, Cat. I/352) catalog
48- 51 I4 pc Dkin Kinematic distance from the CO emission
(Section 3.1)
53- 56 I4 pc Dgaia50 50th quantile of a distance distribution from
Bailer-Jones et al.
(2021AJ....161..147B 2021AJ....161..147B, Cat. I/352)
58- 61 I4 pc Dgaia14 14th quantile of a distance distribution from
Bailer-Jones et al.
(2021AJ....161..147B 2021AJ....161..147B, Cat. I/352)
63- 67 I5 pc Dgaia86 86th quantile of a distance distribution from
Bailer-Jones et al.
(2021AJ....161..147B 2021AJ....161..147B, Cat. I/352)
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 I1 --- Seq Sequential number
3- 19 A17 --- SSTSMOGA IRAC designation SSTSMOGA (GLLL.llll+BB.bbbb)
21- 27 A7 --- ModelSet Model set name (G1)
29- 31 F3.1 kpc Dist Distance taken from Bailer-Jones et al.
(2021AJ....161..147B 2021AJ....161..147B, Cat. I/352)
33- 35 F3.1 Rsun R* Stellar radius
37- 40 I4 K T* Stellar temperature
42- 46 F5.2 Lsun L* Stellar luminosity
48- 50 F3.1 Msun M* ?=- Stellar mass
52- 54 F3.1 Myr Age ?=- Stellar age
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Byte-by-byte Description of file: tablec1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq Sequential number
4- 20 A17 --- SSTSMOGA IRAC designation SSTSMOGA (GLLL.llll+BB.bbbb)
22- 27 F6.2 mJy FJ ?=- 2MASS J flux
29- 33 F5.2 mJy e_FJ ? 2MASS J flux error
35- 40 F6.2 mJy FH ?=- 2MASS H flux
42- 46 F5.2 mJy e_FH ? 2MASS H flux error
48- 53 F6.2 mJy FKs ?=- 2MASS Ks flux
55- 59 F5.2 mJy e_FKs ? 2MASS Ks flux error
61- 65 F5.2 mJy F3.6 ?=- IRAC 3.6um flux
67- 71 F5.2 mJy e_F3.6 ? IRAC 3.6um flux error
73- 78 F6.2 mJy F4.5 ?=- IRAC 4.5um flux
80- 84 F5.2 mJy e_F4.5 ? IRAC 4.5um flux error
86- 91 F6.2 mJy F5.8 ?=- IRAC 5.8um flux
93- 97 F5.2 mJy e_F5.8 ? IRAC 5.8um flux error
99-104 F6.2 mJy F8.0 ?=- IRAC 8.0um flux
106-110 F5.2 mJy e_F8.0 ? IRAC 8.0um flux error
112 A1 --- l_F12 3σ upper limit flag on F12
113-118 F6.2 mJy F12 ?=- AllWISE 12um flux
120-125 F6.2 mJy e_F12 ? AllWISE 12um flux error
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Byte-by-byte Description of file: tablec2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq Sequential number
4- 20 A17 --- SSTSMOGA IRAC designation SSTSMOGA (GLLL.llll+BB.bbbb)
22 A1 --- l_F22 3σ upper limit flag on F22
23- 29 F7.2 mJy F22 ?=- AllWISE 22um flux
31- 36 F6.2 mJy e_F22 ? AllWISE 22um flux error
38- 43 F6.2 mJy F24 ?=- MIPS 24um flux
45- 50 F6.2 mJy e_F24 ? MIPS 24um flux error
52 A1 --- l_F70 σ upper limit flag on F70
53- 59 F7.2 mJy F70 ?=- PACS 70um flux
61- 67 F7.2 mJy e_F70 ? PACS 70um flux error
69 A1 --- l_F100 3σ upper limit flag on F100
70- 76 F7.2 mJy F100 ?=- PACS 100um flux
78- 84 F7.2 mJy e_F100 ? PACS 100um flux error
86 A1 --- l_F160 3σ upper limit flag on F160
87- 94 F8.2 mJy F160 ?=- PACS 160um flux
96-102 F7.2 mJy e_F160 ? PACS 160um flux error
104 A1 --- l_F250 3σ upper limit flag on F250
105-111 F7.2 mJy F250 ?=- SPIRE 250um flux
113-119 F7.2 mJy e_F250 ? SPIRE 250um flux error
121 A1 --- l_F350 3σ upper limit flag on F350
122-128 F7.2 mJy F350 ?=- SPIRE 350um flux
130-135 F6.2 mJy e_F350 ? SPIRE 350um flux error
137 A1 --- l_F500 3σ upper limit flag on F500
138-144 F7.2 mJy F500 ?=- SPIRE 500um flux
146-151 F6.2 mJy e_F500 ? SPIRE 500um flux error
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Byte-by-byte Description of file: tablec3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq Sequential number, within the group
4- 20 A17 --- SSTSMOGA IRAC designation SSTSMOGA (GLLL.llll+BB.bbbb)
22- 25 F4.2 mJy FJ ?=- 2MASS J flux
27- 30 F4.2 mJy e_FJ ? 2MASS J flux error
32- 35 F4.2 mJy FH ?=- 2MASS H flux
37- 40 F4.2 mJy e_FH ? 2MASS H flux error
42- 45 F4.2 mJy FKs ?=- 2MASS Ks flux
47- 50 F4.2 mJy e_FKs ? 2MASS Ks flux error
52- 56 F5.2 mJy F3.6 IRAC 3.6um flux
58- 61 F4.2 mJy e_F3.6 IRAC 3.6um flux error
63- 67 F5.2 mJy F4.5 IRAC 4.5um flux
69- 72 F4.2 mJy e_F4.5 IRAC 4.5um flux error
74- 78 F5.2 mJy F5.8 ?=- IRAC 5.8um flux
80- 83 F4.2 mJy e_F5.8 ? IRAC 5.8um flux error
85- 89 F5.2 mJy F8.0 ?=- IRAC 8.0um flux
91- 94 F4.2 mJy e_F8.0 ? IRAC 8.0um flux error
96-101 F6.2 mJy F12 AllWISE 12um flux
103-106 F4.2 mJy e_F12 AllWISE 12um flux error
108-114 F7.2 mJy F22 AllWISE 22um flux
116-120 F5.2 mJy e_F22 AllWISE 22um flux error
122-125 F4.2 mJy F24 ?=- MIPS 24um flux
127-130 F4.2 mJy e_F24 ? MIPS 24um flux error
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Byte-by-byte Description of file: tablec4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq Sequential number
4- 20 A17 --- SSTSMOGA IRAC designation SSTSMOGA (GLLL.llll+BB.bbbb)
21 A1 --- n_SSTSMOGA [*] * for sources with different
classifications obtained here and in Winston
et al. (2019ApJ...880....9W 2019ApJ...880....9W, J/ApJ/880/9)
23- 24 A2 --- ClassML Classification obtained using machine learning
(Section 3.3)
26 A1 --- n_ClassML [t] Note on ClassML (1)
30- 31 A2 --- ClassCC Classification obtained using color-color
diagrams when the kinematic distance was also
available (Section 3.2)
33- 34 A2 --- ClassCCnd Classification obtained using color-color
diagrams created using the criteria which did
not require distance (see text)
36- 37 A2 --- ClassIRAC Classification obtained in Winston et al.
(2019ApJ...880....9W 2019ApJ...880....9W, J/ApJ/880/9)
using only IRAC bands
39- 40 A2 --- ClassMPIS Classification obtained in Winston et al.
(2019ApJ...880....9W 2019ApJ...880....9W, J/ApJ/880/9)
using IRAC and MIPS bands
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Note (1): Note as follows:
t = For sources which belonged to the training or test samples in the ML
calculations, the class is adopted from the CC method
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Global notes:
Note (G1): Model set names:
----------------------------------------------------------------------------
Model Nb Compoments Group
sources
----------------------------------------------------------------------------
sp--s-i 12 star + passive disk; Rinner = Rsub d
sp--h-i 4 star + passive disk; variable Rinner d
sp--smi 5 star + passive disk + medium; Rinner = Rsub d
sp--hmi 2 star + passive disk + medium; variable Rinner d
s-ubsmi 1 star + Ulrich envelope + cavity + medium; Rinner =Rsub e
spu-hmi 1 star + passive disk + Ulrich envelope +
medium; variable Rinner d+e
spubsmi 1 star + passive disk + Ulrich envelope + cavity + medium;
Rinner = Rsub d+e
----------------------------------------------------------------------------
The model set names are from Robitaille (2017A&A...600A..11R 2017A&A...600A..11R).
Seven characters in the model set names indicate which component is present;
they are (in order): s: star; p: passive disk,
p or u: power-law or Ulrich envelope; b: bipolar cavities; h: inner hole;
m: ambient medium; and i: interstellar dust.
A dash (-) is used when a component is absent. Rinner is the inner radius
for the disk, envelope, and the ambient medium - when one or more of these
components are present. Rsub is the dust sublimation radius.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 22-Sep-2022