J/AJ/168/278 Positions, plx, & phot. from Gaia for Berkeley 39 (Chand+, 2024)
Characterization of blue and yellow straggler stars of Berkeley 39.
Chand K., Rao K.K., Vaidya K., Panthi A.
<Astron. J., 168, 278 (2024)>
=2024AJ....168..278C 2024AJ....168..278C
ADC_Keywords: Stars, blue; Clusters, open; Photometry, ugriz; Stars, peculiar;
Ultraviolet
Keywords: Ultraviolet astronomy ; Blue straggler stars ;
Yellow straggler stars ; Open star clusters ; Stellar populations
Abstract:
We characterize blue straggler stars (BSSs) and yellow straggler stars
(YSSs) of the open cluster (OC) Berkeley 39 using multiwavelength
observations including the Swift/Ultraviolet and Optical Telescope
(UVOT). Our analysis also makes use of ultraviolet (UV) data from
Galaxy Evolution Explorer, optical data from Gaia DR3 and Panoramic
Survey Telescope and Rapid Response System, and infrared data from Two
Micron All Sky Survey, Spitzer/IRAC, and Wide-field Infrared Survey
Explorer. Berkeley 39 is a ∼6Gyr old Galactic OC located at a distance
of ∼4200pc. We identify 729 sources as cluster members utilizing a
machine-learning algorithm, ML-MOC, on Gaia DR3 data. Of these,
17 sources are classified as BSS candidates and four as YSS candidates.
We construct multiwavelength spectral energy distributions (SEDs) of
16 BSS and two YSS candidates, within the Swift/UVOT field, to analyze
their properties. Out of these, eight BSS candidates and both the YSS
candidates are successfully fitted with single-component SEDs.
Five BSS candidates show marginal excess in the near-UV (NUV;
fractional residual <0.3 in all but one UVOT filter), whereas three
BSS candidates show moderate to significant excess in the NUV
(fractional residual >0.3 in at least two UVOT filters). We present
the properties of the BSS and YSS candidates, estimated based on the
SED fits.
Description:
In order to characterize the BSS and YSS populations, we use
multiwavelength data, ranging from UV to infrared (IR).
UV data: The fluxes of sources in UV wavelengths are obtained from the
Ultraviolet and Optical Telescope (Swift/UVOT) and Galaxy Evolution
Explorer (GALEX). The Swift spacecraft is equipped with UVOT, a 30cm
telescope sensitive in the optical/UV band in the wavelength range of
170-650nm. We utilize near-UV (NUV) data (Siegel+2019, J/AJ/158/35)
from UVOT in this work. Berkeley 39 was observed by Swift/UVOT in
three UV filters, UVW2 (180-260nm), UVM2 (200-280nm), and UVW1
(220-400nm), in 2011. In addition to the Swift/UVOT data, we also use
data from GALEX, a 50cm aperture space-based telescope which observed
Berkeley 39 in its NUV band (1770-2730Å).
Optical data: Gaia data (DR3; Gaia Collab.+2022, I/355) provides
proper motions, parallaxes, and three-band photometry (G, GBP,
GRP) for over a billion sources observed between 25 July 2014 and
28 May 2017. The wavelength of filter G is centered at 673nm, GBP at
532nm, and GRP at 797nm. The Panoramic Survey Telescope and Rapid
Response System (Pan-STARRS) is a ground-based telescope which
observed from 2010 to 2015 for its first data release
(Chambers+2019, II/349). It utilizes five filters, g, r, i, z, and y,
with effective wavelengths 481, 617, 752, 866, and 962nm respectively.
IR data: Two Micron All Sky Survey (2MASS; Cutri+2003, II/246)
contains near-IR photometric measurements in the J (1.24um),
H (1.66um), and Ks (2.16um) bands taken between 1997 June and
2001 February. Spitzer/IRAC is a space-based observatory containing a
four-channel camera that provides mid-IR wavelength fluxes and
simultaneous broadband images at I1 (3.6um), I2 (4.5um), I3 (5.8um),
and I4 (8.0um). In 2006, spitzer/IRAC observed Berkeley 39 in all four
IRAC channels with an exposure time of 26.8s. The Wide-field Infrared
Survey Explorer (WISE) is a mid-IR full sky survey which took place
between 29 September 2010 and 1 February 2011. It includes a 40cm
diameter telescope and four IR detectors, namely, W1, W2, W3, and W4,
with wavelengths centered at 3.35um, 4.60um, 11.56um, and 22.09um,
respectively. Since the Spitzer/IRAC filters have better resolution
than WISE, we use WISE W1, W2 fluxes only when Spitzer/IRAC fluxes are
unavailable.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
figs.dat 136 729 The spatial distribution, proper motion distribution
and parallax distribution of cluster members using
ML-MOC algorithm on Gaia DR3 data
table3.dat 410 18 *Coordinates & fluxes of BSS and YSS candidates
across all utilized filters
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Note on table3.dat: All fluxes (in erg/s/cm/Å) are newly added from Gaia,
GALEX, Pan-STARRS, 2MASS, and WISE surveys, except:
- Swift/UVOT UVW2, UVM2, and UVW1 fluxes for all objects
- 2MASS J flux for BSS14
- Pan-STARRS1 i, z, and y fluxes for BSS13
- Pan-STARRS1 z flux for BSS6
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
II/312 : GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)
II/335 : Revised cat. of GALEX UV sources (GUVcat_AIS GR6+7) (Bianchi+ 2017)
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)
J/AJ/113/1723 : UBVI photometry in 4 open clusters (Kassis+, 1997)
J/A+A/463/789 : Blue stragglers in open clusters (Ahumada+, 2007)
J/A+A/523/A48 : Gaia photometry (Jordi+, 2010)
J/ApJ/730/67 : Radial velocities of low-mass white dwarfs (Brown+, 2011)
J/A+A/548/A122 : Berkeley 39 stars photometry & abundances (Bragaglia+, 2012)
J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)
J/AJ/158/35 : Swift UVOT Stars. III. Gal. open clusters (Siegel+, 2019)
J/MNRAS/503/236 : UVIT catalog & membership of 6 open clusters (Jadhav+, 2021)
J/A+A/650/A67 : Blue & yellow straggler stars in open clusters (Rain+, 2021)
Byte-by-byte Description of file: figs.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR3 Gaia DR3 (I/355) identifier
21- 31 F11.7 deg RAdeg [116.4/117] Right ascension (ICRS) at Ep=2016
33- 42 F10.7 deg DEdeg [-4.9/-4.4] Declination (ICRS) at Ep=2016
44- 48 F5.3 mas plx [0.1/0.41] Gaia DR3 parallax
50- 54 F5.3 mas e_plx [0.01/0.51] Standard error in plx
56- 61 F6.3 mas/yr pmRA [-2.1/-1.4] Gaia DR3 proper motion in right
ascension
63- 67 F5.3 mas/yr e_pmRA [0.01/0.43] Standard error in pmRA
69- 74 F6.3 mas/yr pmDE [-1.9/-1.3] Gaia DR3 proper motion in
declination
76- 80 F5.3 mas/yr e_pmDE [0.009/0.32] Standard error in pmDE
82- 89 F8.5 mag Gmag [12.3/20] Gaia DR3 G-band (673nm) mean
magnitude
91- 97 F7.5 mag e_Gmag [0.002/0.005] Error in Gmag
99- 106 F8.5 mag BPmag [13.2/20.7] Integrated Gaia DR3 BP (532nm)
mean magnitude
108- 114 F7.5 mag e_BPmag [0.002/0.12] Error in BPmag
116- 123 F8.5 mag RPmag [11.4/19.3] Gaia DR3 RP (797nm) mean
magnitude
125- 131 F7.5 mag e_RPmag [0.003/0.05] Error in RPmag
133- 136 F4.2 --- Mm [0.21/0.98] Membership probability
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- ID Name of the source
7- 25 I19 --- GaiaDR3 Gaia DR3 identifier (I/355)
27- 35 F9.5 deg RAdeg [116.6/116.8] Right ascension (ICRS)
at Ep=2016.0
37- 44 F8.5 deg DEdeg [-4.8/-4.5] Declination (ICRS) at Ep=2016.0
46- 53 E8.3 cW/m2/nm F(UVW2) [1.4e-17/9.9e-16] Swift/UVOT UVW2
(180-260nm) flux (J/AJ/158/35)
55- 62 E8.3 cW/m2/nm e_F(UVW2) [2.4e-18/1.9e-17] F(UVW2) uncertainty
64- 71 E8.3 cW/m2/nm F(UVM2) [1.1e-17/7.8e-16] Swift/UVOT UVM2
(200-280nm) flux (J/AJ/158/35)
73- 80 E8.3 cW/m2/nm e_F(UVM2) [2.4e-18/1.91e-17] F(UVM2) uncertainty
82- 89 E8.3 cW/m2/nm F(UVW1) [5.3e-17/7.5e-16] Swift/UVOT UVW1
(220-400nm) flux (J/AJ/158/35)
91- 99 E9.4 cW/m2/nm e_F(UVW1) [4.5e-18/1.4e-17] F(UVW1) uncertainty
101- 108 E8.3 cW/m2/nm F(NUV) [4.6e-17/1.3e-15]? GALEX NUV (177-273nm)
flux (II/335)
110- 117 E8.3 cW/m2/nm e_F(NUV) [8.7e-19/2.9e-18]? F(NUV) uncertainty
119- 126 E8.3 cW/m2/nm F(BP) [5.4e-16/4.3e-15] Gaia BP (532nm) flux
(I/355)
128- 135 E8.3 cW/m2/nm e_F(BP) [3.0e-18/1.5e-17] F(BP) uncertainty
137- 144 E8.3 cW/m2/nm F(G) [4.4e-16/3.2e-15] Gaia G (673nm) flux
(I/355)
146- 153 E8.3 cW/m2/nm e_F(G) [1.1e-18/8.4e-18] F(G) uncertainty
155- 162 E8.3 cW/m2/nm F(RP) [3.4e-16/2.2e-15] Gaia RP (797nm) flux
(I/355)
164- 171 E8.3 cW/m2/nm e_F(RP) [1.8e-18/8.4e-18] F(RP) uncertainty
173- 180 E8.3 cW/m2/nm F(g) [6.0e-16/4.97e-15] Pan-STARRS1 g (481nm)
flux (II/349)
182- 190 E9.4 cW/m2/nm e_F(g) [1.3e-18/2.6e-16] F(g) uncertainty
192- 199 E8.3 cW/m2/nm F(r) [5.0e-16/3.5e-15] Pan-STARRS1 r (617nm)
flux (II/349)
201- 208 E8.3 cW/m2/nm e_F(r) [6.4e-19/1.4e-16] F(r) uncertainty
210- 217 E8.3 cW/m2/nm F(i) [3.7e-16/2.4e-15] Pan-STARRS1 i (752nm)
flux (II/349)
219- 226 E8.3 cW/m2/nm e_F(i) [9.2e-19/7.7e-18] F(i) uncertainty
228- 235 E8.3 cW/m2/nm F(z) [2.8e-16/1.7e-15] Pan-STARRS1 z (866nm)
flux (II/349)
237- 244 E8.3 cW/m2/nm e_F(z) [8.2e-19/7.97e-18] F(z) uncertainty
246- 253 E8.3 cW/m2/nm F(y) [2.4e-16/1.5e-15] Pan-STARRS1 y (962nm)
flux (II/349)
255- 262 E8.3 cW/m2/nm e_F(y) [1.2e-18/8.7e-18] F(y) uncertainty
264- 271 E8.3 cW/m2/nm F(J) [1.2e-16/7.6e-16] 2MASS J (1.24um) flux
(II/246)
273- 280 E8.3 cW/m2/nm e_F(J) [7.8e-18/2.2e-17] F(J) uncertainty
282- 290 E9.4 cW/m2/nm F(H) [5.7e-17/3.5e-16] 2MASS H (1.66um) flux
(II/246)
292- 300 E9.4 cW/m2/nm e_F(H) [6.4e-18/1.2e-17] F(H) uncertainty
302- 309 E8.3 cW/m2/nm F(Ks) [1.0e-17/1.4e-16] 2MASS Ks (2.16um) flux
(II/246
311- 318 E8.3 cW/m2/nm e_F(Ks) [1.7e-18/6.4e-18] F(Ks) uncertainty
320- 327 E8.3 cW/m2/nm F(I1) [3.3e-18/1.95e-17]? Spitzer/IRAC I1
(3.6um) flux (
329- 336 E8.3 cW/m2/nm e_F(I1) [2.1e-20/4.6e-20]? F(I1) uncertainty
338- 345 E8.3 cW/m2/nm F(I2) [1.5e-18/9.1e-18]? Spitzer/IRAC I2
(4.5um) flux
347- 355 E9.4 cW/m2/nm e_F(I2) [2.0e-20/3.8e-20]? F(I2) uncertainty
357- 364 E8.3 cW/m2/nm F(I3) [1.2e-18/3.5e-18]? Spitzer/IRAC I3 (5.8um)
flux
366- 373 E8.3 cW/m2/nm e_F(I3) [4.1e-20/5.3e-20]? F(I3) uncertainty
375- 382 E8.3 cW/m2/nm F(W1) [4.1e-18/2.9e-17]? WISE W1 (3.35um) flux
(II/311)
384- 392 E9.4 cW/m2/nm e_F(W1) [1.8e-19/1.6e-18]? F(W1) uncertainty
394- 401 E8.3 cW/m2/nm F(W2) [1.1e-18/7.3e-18]? WISE W2 (4.60um) flux
(II/311)
403- 410 E8.3 cW/m2/nm e_F(W2) [1.3e-19/4.6e-19]? F(W2) uncertainty
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History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 05-Sep-2025