J/AJ/158/68 Short-period variables in young open cluster Stock 8 (Lata+, 2019)
Short-period variable stars in young open cluster Stock 8.
Lata S., Pandey A.K., Yadav R.K., Richichi A., Irawati P., Panwar N.,
Dhillon V.S., Marsh T.R.
<Astron. J., 158, 68 (2019)>
=2019AJ....158...68L 2019AJ....158...68L (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, variable ; Stars, pre-main sequence ;
Photometry, UBVRI ; Photometry, infrared ; Stars, masses ;
Stars, ages ; Effective temperatures
Keywords: open clusters and associations: general -
stars: variables: T-Tauri, Herbig Ae/Be
Abstract:
We present time-series photometry in the field of Stock 8 and
identified 130 short-period variable stars. Twenty-eight main-sequence
and 23 pre-main-sequence variables are found to be part of cluster Stock 8.
The main-sequence variables are classified as slow pulsators of the B-type,
β Cep, and δ Scuti stars. Fourteen main-sequence stars
could be new class variables as discussed by Mowlavi et al. (2013,
J/A+A/554/A108) and Lata et al. (2011MNRAS.418.1346L 2011MNRAS.418.1346L; 2012MNRAS.427.1449L 2012MNRAS.427.1449L;
2014, J/MNRAS/442/273; 2016MNRAS.456.2505L 2016MNRAS.456.2505L). The age and mass of
pre-main-sequence variables are found to be ~<5 Myr and in the mass range
of 0.5-2.8 M☉, respectively. These pre-main-sequence stars could
be T-Tauri variables. We have found 5 and 2 of 23 pre-main-sequence
variables as classical T-Tauri stars and Herbig Ae/Be stars, respectively,
whereas 16 pre-main-sequence stars are classified as weak-line T-Tauri
stars.
Description:
Photometric observations of young open cluster Stock 8 were carried out
on a total of 18 nights during 2014-2016 from four telescopes. The 0.5 m
telescope at Thai National Observatory (TNO) was used for observations
of field containing Stock 8. An Andor Tech 2048x2048 pixels CCD camera
attached to the 0.5 m Schmidt-Cassegrain Telescope of TNO was used. The
plate scale was about 0.684 arcsec/pixel. The resulting field of view
of each image was ∼23.9x23.9 arcmin2. The observations of Stock 8 were
taken in the V band from 2015 November 15 to 2015 December 9. V-band
photometric imaging of Stock 8 was obtained using the ARIES 1.04 m
telescope with a 2kx2k CCD. The plate scale of 0.37 arcsec/pixel provides
a field of view of about 13'x13'. In order to improve the signal-to-noise
ratio, a 2x2 binning mode was used. Further, optical observations of
the Stock 8 region in the V band have also been carried out using the 2 m
Himalayan Chandra Telescope (HCT) of the Indian Astronomical Observatory
(IAO) and Himalayan Faint Object Spectrograph Camera (HFOSC). The detector
used in the HFOSC is a 2kx4k SiTe chip with a pixel size of 15x15 µm.
It has plate scale of 0.296 arcsec/pixel, which gives a 10x10 arcmin2
field of view.
The UBVI data of Stock 8 have been taken from Jose et al. (2008,
J/MNRAS/384/1675; 2017, J/ApJ/836/98), whereas the NIR data have been
taken from the 2MASS Point Source Catalogs (PSC; Cutri et al. 2003,
Cat. II/246). The 2MASS counterparts of the variables were searched
using a match value of 3". The 2MASS magnitudes and colors were
transformed to the Caltech (CIT) photometric system using the
relations given on the 2MASS website. We have also used NASA's
Wide-field Infrared Survey Explorer (WISE) data (Cutri et al. 2012,
Cat. II/311) taken at wavelengths 3.4, 4.6, 12.0, and 22.0 µm.
Objects:
--------------------------------------------------
RA (ICRS) DE Designation(s)
--------------------------------------------------
05 28 07.5 +34 25 42 Stock 8 = C 0524+343
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 130 130 The photometric data, period, amplitude, time
of maximum brightness and classification of
130 variables in the region of Stock 8
table2.dat 32 242813 Data for the variable stars
table4.dat 47 23 Mass and age of probable PMS stars
table5.dat 34 24 The effective temperature (Teff), bolometric
correction (BC), bolometric magnitude (Mbol),
and luminosity (L)
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
J/MNRAS/384/1675 : BVRIc photometry of Stock 8 (Jose+, 2008)
J/A+A/554/A108 : Periodic variables in NGC 3766 (Mowlavi+, 2013)
J/ApJ/836/98 : YSOs search in Stock 8 with opt. to IR photom. (Jose+, 2017)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- ID Variable identifier (VNNN)
6- 14 F9.6 deg RAdeg Right Ascension in decimal degrees (J2000)
16- 24 F9.6 deg DEdeg Declination in decimal degrees (J2000)
26- 31 F6.3 mag Vmag [8.953/18.877]? Apparent V band magnitude (1)
33- 38 F6.3 mag (U-B) [-0.67/0.929]? The (U-B) color (1)
40- 44 F5.3 mag (B-V) [0.19/6.442]? The (B-V) color (1)
46- 50 F5.3 mag (V-I) [0.282/3.604]? The (V-I) color (1)
52- 57 F6.3 mag Jmag [7.124/16.052]? Apparent 2MASS J band magnitude (2)
59- 64 F6.3 mag Hmag [5.671/15.706]? Apparent 2MASS H band magnitude (2)
66- 71 F6.3 mag Ksmag [4.75/15.065]? Apparent 2MASS Ks band magnitude
(2)
73- 80 F8.6 d Per [0.050593/0.64886] Probable period
82- 86 F5.3 mag Amp [0.008/0.456] The V band amplitude
88- 97 F10.6 d T0 [15.28156/450.124711] Date of maximum brightness;
JD-2457000
99-102 F4.2 --- Prob [0/1] Variability probability
104-112 A9 --- c1 Classification of star from Jose et al. (2017,
J/ApJ/836/98)
114-130 A17 --- c2 Present classification of variable (3)
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Note (1): From Jose et al. (2008, J/MNRAS/384/1675) and Jose et al. (2017,
J/ApJ/836/98).
Note (2): 2MASS Point Source Catalog (Cutri et al. 2003, Cat. II/246).
Note (3): Classification as follows:
BP = Blue plume of the Norma-Cygnus arm;
MS = Main-sequence star;
PMS = Pre-main-sequence star;
SPB = Slowly pulsating B star;
CTTS = Classical T-Tauri star;
WTTS = Weak-line T-Tauri star;
HAeBe = Herbig Ae/Be star.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- ID Variable identifier (VNNN)
6- 19 F14.6 d JD Julian Date of observation
21- 26 F6.3 mag Vmag [9.305/20.927] Apparent V band magnitude
28- 32 F5.3 mag e_Vmag [0.001/0.533] Uncertainty in Vmag
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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- 4 A4 --- ID Variable identifier (VNNN)
6- 9 F4.2 Msun MassCMD [0.55/2.75]? Mass estimated from V/(V-I)
color-magnitude diagram (CMD)
11- 14 F4.2 Msun e_MassCMD [0.01/0.15]? Uncertainty in MassCMD
16- 17 A2 --- l_AgeCMD [>≤ ] Limit flag on AgeCMD
18- 22 F5.2 Myr AgeCMD [0.01/10]? Age estimated from V/(V-I) CMD
24- 27 F4.2 Myr e_AgeCMD [0.01/1.01]? Uncertainty in AgeCMD
29- 32 F4.2 Msun MassSED [1.01/5.68]? Mass estimated from the spectral
energy distribution (SED) analysis
34- 37 F4.2 Msun e_MassSED [0.14/1.37]? Uncertainty in MassSED
39- 42 F4.2 Myr AgeSED [0.28/6.39]? Age estimated from the SED analysis
44- 47 F4.2 Myr e_AgeSED [0.12/3.3]? Uncertainty in AgeSED
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- ID Variable identifier (VNNN)
6- 10 F5.3 [K] logTeff [3.95/4.411] Log effective temperature
12- 19 F8.5 mag BC [-2.25/0.1406] Bolometric correction
21- 28 F8.5 mag Mbol [-6.097/1.55] Bolometric magnitude
30- 34 F5.3 [Lsun] logL [1.273/4.332] Log luminosity (logL/L☉)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 25-Sep-2019