J/AJ/168/255 U-SMAC II. FUV catalog of sources detected in SMC (Hota+, 2024)
UVIT Study of the MAgellanic Clouds (U-SMAC).
II. A far-UV catalog of the Small Magellanic Cloud: morphology and kinematics
of young stellar population.
Hota S., Subramaniam A., Nayak P.K., Subramanian S.
<Astron. J., 168, 255 (2024)>
=2024AJ....168..255H 2024AJ....168..255H
ADC_Keywords: Ultraviolet; Galaxies, photometry; Galaxies, dwarf;
Magellanic Clouds; Surveys; Optical; Infrared
Keywords: Magellanic Clouds ; Galaxy photometry ; Ultraviolet astronomy ;
Galaxy evolution
Abstract:
The Small Magellanic Cloud (SMC) is an irregular dwarf galaxy that has
recently undergone an interaction with the Large Magellanic Cloud. The
young massive stars in the SMC formed in the disturbed low-metallicity
environment are important targets in astrophysics. We present a
catalog of ∼76,800 far-ultraviolet (FUV) sources toward the SMC
detected using the Ultra Violet Imaging Telescope onboard AstroSat. We
created an FUV catalog with ∼62,900 probable SMC members which
predominantly comprise main-sequence, giant, and subgiant stars. We
selected four young populations (Young 1, Young 2, Young 3, and Blue
Loop (BL) stars) identified from the Gaia optical color-magnitude
diagram to study the morphology and kinematics of the young SMC using
this catalog. We detect a clumpy morphology with a broken bar, a
shell-like structure, and the inner SMC Wing for the four stellar
populations. The eastern region and the northeastern regions are
mainly populated by Young 1, 2, and 3 stars. The central region
predominantly has the Young 2 and 3 populations, whereas the SW has BL
stars, and Young 2 and 3 stars. The 2D kinematic study using proper
motion (PM) reveals that Young 2 and 3 populations show two
kinematically distinct subpopulations with low and high PM dispersion,
whereas the Young 1 and BL stars show two kinematically distinct
populations with low dispersion. Our analysis points to a kinematic
disturbance along the R.A. direction for stars younger than ∼150Myr
located in the eastern region, with no significant disturbance along
the decl.
Description:
The Ultra Violet Imaging Telescope (UVIT), an instrument on AstroSat,
comprises two distinct telescopes of 38cm in diameter; one is
dedicated to the FUV (130-180nm) channel, while the other one is for
NUV (200-300nm) and visible (VIS: 350-550nm) channels. The FUV and NUV
channels are used to obtain the photometric data, and the VIS channel
is used for drift correction due to the spacecraft. UVIT has a field
of view of ∼28' with a spatial resolution of ∼1.4".
In this work, we utilized FUV images of 39 UVIT pointings in the
medium passband filter; F172M (silica: 1717±125Å). The
observations took place from August to November 2020 for 36 pointings,
in February 2022 for two more pointings, and October 2023 for one
last. Out of 39 SMC fields, 25 SMC fields have exposure time >900s,
nine fields have exposure time between 400 and 830s, while three
fields have exposure time between 300 and 400s. Two SMC fields, SMC-02
and SMC-42, exhibit shorter exposure time (<200s). SMC-02 is situated
on the periphery of the SMC's main body, whereas SMC-42 is located
within the inner region of the SMC Wing. We note that this study does
not include the regions of the SMC covered by Hota+ (2024MNRAS.532..322H 2024MNRAS.532..322H)
and Devaraj+2023 (J/ApJ/946/65).
To produce the FUV catalog, we combined the photometric data of all
the 39 UVIT observed fields. For the catalog, we selected FUV sources
with a magnitude error of ≤0.2mag (for signal-to-noise ratio; S/N≥5)
and an FUV magnitude >13.2mag.
To better characterize the detected FUV sources in the SMC, we
cross-matched these FUV sources with IR (the VISTA Magellanic survey
(VMC DR6), see II/375, from the European Southern Observatory (ESO)
archive) and optical (Gaia DR3, see I/355) data. See Section 2.4.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 89 76838 FUV catalog of the sources detected in the direction
of the SMC
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See also:
II/375 : VISTA Magellanic Survey (VMC) cat. (YJKs) DR6 (Cioni+, 2011)
II/351 : VISTA Magellanic Survey (VMC) catalog (Cioni+, 2011)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)
J/AJ/113/1011 : UV Observations of the SMC (Cornett+ 1997)
J/AJ/127/1531 : Star formation history of SMC (Harris+, 2004)
J/AJ/140/416 : IR photometry of massive stars in the SMC (Bonanos+, 2010)
J/A+A/517/A50 : Ages & lum. of young SMC/LMC star clusters (Glatt+, 2010)
J/other/Sci/337.444 : RV curves of Galactic massive O stars (Sana+, 2012)
J/ApJS/213/34 : Veloc. of Cygnus OB2 massive binaries (Kobulnicky+, 2014)
J/ApJS/215/15 : SMaSH+: observations and companion detection (Sana+, 2014)
J/MNRAS/449/639 : VMC survey. XIV. SFR in SMC (Rubele+, 2015)
J/A+A/591/A11 : SMC BV photometry of 9 star cluster fields (Dias+, 2016)
J/ApJ/816/49 : Spitzer/IRAC observations of SMC Cepheids (Scowcroft+, 2016)
J/AJ/154/199 : SMASH: Survey of MAgellanic Stellar History (Nidever+, 2017)
J/MNRAS/472/808 : YJKs light curves of SMC Classical Cepheids (Ripepi+, 2017)
J/A+A/616/A187 : SMC clusters age-dating & classification (Nayak+, 2018)
J/A+A/628/A51 : Magellanic Clouds reddening map (Joshi+, 2019)
J/ApJ/887/267 : OB stars embedded in the HI gas of SMC (Murray+, 2019)
J/MNRAS/495/98 : Tidal scars of the Small Magellanic Cloud (De Leo+, 2020)
J/ApJ/904/13 : RVel for 10 giant eclipsing binaries (Graczyk+, 2020)
J/ApJS/247/47 : UV survey of M31 with UVIT on AstroSat (Leahy+, 2020)
J/A+A/649/A7 : MC structure and properties (Gaia Collaboration+, 2021)
J/AJ/161/74 : SMASH DR2. 197 SMASH fields (Nidever+, 2021)
J/MNRAS/502/2859 : The VMC survey XLI - PMs within the SMC (Niederhofer+, 2021)
J/MNRAS/504/2983 : Reddening of SMC red clump stars (Tatton+, 2021)
J/MNRAS/513/5847 : Red supergiants in binary systems. I. SMC (Patrick+, 2022)
J/ApJ/946/65 : AstroSat/UVIT obs. SMC: point-source cat. (Devaraj+, 2023)
J/A+A/672/A65 : Clean SMC stellar samples (Jimenez-Arranz+, 2023)
J/A+A/690/A289 : Binarity at LOw Metallicity (BLOeM). I. (Shenar+, 2024)
J/ApJS/275/34 : UVIT DR1, comprehensive catalog of UVIT obs. (Piridi+, 2024)
http://astrobrowse.issdc.gov.in/astro_archive/archive/Home.jsp : ISRO Science
Data Archive AstroSat Archive
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq [0/76837] Sequential Index
7- 10 A4 --- --- [UVIT]
11- 15 I05 --- UVIT [0/76837] UVIT identification number
17- 28 F12.9 deg RAdeg [9.6/22.9] Right ascension from UVIT (ICRS)
30- 41 F12.8 deg DEdeg [-74/-71] Declination from UVIT (ICRS)
43- 48 F6.3 mag FUVmag [13.2/20.4] FUV (172nm) AB magnitude
50- 54 F5.3 mag e_FUVmag [0.01/0.2] Uncertainty in FUVmag
56- 67 I12 --- VMC [558345786944/558383763884]? VMC DR6 (II/375)
PSF source identifier (1)
69- 87 I19 --- GaiaDR3 ? Gaia DR3 (II/355) source identifier
(source_id) (1)
89 A1 --- Mm [NY] Probable SMC member? (2)
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Note (1): Null or black space in the rows of Gaia source ID and VMC
source ID columns means these UVIT sources do not have Gaia and
VMC cross-matched.
Note (2): Probable SMC member identified by the truncated-optimal NN
with RUWE<1.4 (62,901 sources) are presented in the last column of the
table where Y and N stand for "(Y)es" and "(N)o" respectively.
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History:
From electronic version of the journal
References:
Hota et al. Paper I. 2024MNRAS.532..322H 2024MNRAS.532..322H Cat. J/MNRAS/532/322
Hota et al. Paper II. 2024AJ....168..255H 2024AJ....168..255H This catalog
(End) Prepared by [AAS], Robin Leichtnam [CDS] 26-Aug-2025