J/MNRAS/487/3505 Variable stars in NGC 2244 (Michalska, 2019)
Variable stars in young open cluster NGC 2244.
Michalska G.
<Mon. Not. R. Astron. Soc. 487, 3505-3522 (2019)>
=2019MNRAS.487.3505M 2019MNRAS.487.3505M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, variable ; Stars, pre-main sequence ;
Photometry, UBVRI ; Photometry, infrared
Keywords: stars: variable: delta Scuti -
stars: variables: T Tauri, Herbig Ae/Be -
open clusters and associations: individual: NGC 2244 - infrared: stars
Abstract:
We present results of the UBVIc variability search for variable stars
in the young open cluster NGC 2244. In total, we found 245 variable
stars. Most of them, are pre-main sequence variables with irregular
variations typical for classical T Tauri stars (CTTSs). We found also
23 periodic variables, probably weak-lined T Tauri stars (WTTSs). We
detected also four candidates for δ Scuti stars and 7 eclipsing
binaries.
Based on the mid-infrared Spitzer and WISE photometry and near
infrared JHKS 2MASS photometry, we classified 104 young stellar
sources among our variables: 1 Class I object, 1 Class I/flat spectrum
object, 4 flat spectrum objects, 91 Class II objects, and 7 transition
disc objects. This classification, together with r'i'Hα IPHAS
photometry and JHK UKIDSS photometry, were used for identification of
pre-main sequence stars among irregular and periodic variables. In
this way, 97 CTTS candidates (96 irregular and one periodic variable),
68 WTTS candidates (54 irregular and 14 periodic variables), and 6
Herbig Ae/Be stars were found. For 223 variable stars we calculated
membership probability based on proper motions from Gaia DR2
catalogue. Majority of them, 143 stars, are cluster members with
probability greater than 70 per cent. For only 36 variable stars the
membership probability is smaller than 20 per cent.
Description:
The photometric observations of NGC 2244 were carried out with the
Yale SMARTS 1-m telescope at Cerro Tololo Inter-American Observatory
in Chile. Based on the mid-infrared Spitzer and WISE photometry and
near infrared JHKs 2MASS photometry we classified 104 young stellar
sources among our variables: 1 Class I object, 1 Class I/flat spectrum
object, 4 flat spectrum objects, 91 Class II objects and 7 transition
disk objects. Applying r'i'Hα IPHAS photometry and JHK UKIDSS
photometry we found 97 candidates to CTTSs and 68 stars which appear
to be WTTSs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 108 245 The variable stars in NGC 2244, coordinates,
UBVIc photometry and properties
table2.dat 117 245 The 2MASS, UKIDSS, Spitzer IRAC/MIPS, and IPHAS
photometry of variable stars in NGC 2244
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/316 : UKIDSS-DR6 Galactic Plane Survey (Lucas+ 2012)
II/328 : AllWISE Data Release (Cutri+ 2013)
II/321 : IPHAS DR2 Source Catalogue (Barentsen+, 2014)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJ/660/1532 : Spitzer/IRAC-MIPS survey of NGC 2244 (Balog+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Name [1/245] Star designation
5 I1 h RAh Right ascension (J2000)
7- 8 I2 min RAm Right ascension (J2000)
10- 14 F5.2 s RAs Right ascension (J2000)
16 A1 --- DE- Declination sign (J2000)
17 I1 deg DEd Declination (J2000)
19- 20 I2 arcmin DEm Declination (J2000)
22- 25 F4.1 arcsec DEs Declination (J2000)
27- 32 F6.3 mag Vmag Johnson V magnitude
34- 38 F5.3 mag V-Ic Johnson-Cousins V-Ic colour index
40- 44 F5.3 mag B-V ? Johnson B-V colour index
46- 51 F6.3 mag U-B ? Johnson U-B colour index
53 A1 --- XVar [abc-] X-ray variability characterization (1)
55- 62 A8 --- HaVar Hα excess (2)
64- 67 A4 --- MIRVar Classification based on MIR photometry (3)
69 A1 --- --- [(]
70- 74 F5.2 --- alpha ? SED slope (4)
75 A1 --- n_alpha [)] Note on alpha (4)
77- 82 A6 --- Var Variability type (5)
84 A1 --- Reg [FTP] The area in (J-H)-(H-K) diagram (6)
86- 89 F4.1 % Prob ? Memberdhip probability (7)
91-100 A10 --- CName The catalogue name (8)
102-108 A7 --- Notes Additional notes (9)
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Note (1): X-ray variability taken from Wang et al. (2008, Cat. J/ApJ/675/464)
as follows:
a = no evidence for variability
b = possibly variable
c = definitely variable
Note (2): Hα emission code as follows:
IA = stars with Hα photometric eq. width, EW(Hα), above the
empirical threshold in (r'-Hα)-(r'-i') diagram at 3σ
confidence level based on IPHAS photometry (Barentsen et al., 2014,
Cat. II/321; see Sect. 6.1)
Ia = stars with EW(Hα)>10 Angstroem (Å) based on IPHAS photometry
(see Sect. 6.1)
Ib = stars with EW(Ha) between 0 and 10Å based on IPHAS photometry
(see Sect. 6.1)
BC = stars with Hα excess (Berghoefer & Christian, 2002A&A...384..890B 2002A&A...384..890B)
PS = stars with Hα excess (Park & Sung, 2002AJ....123..892P 2002AJ....123..892P)
Note (3): Classification based on Spitzer photometry (see Sect. 3) as follows:
I = Class I objects
II = Class II objects
TD = transition discs objects
FS = flat spectrum objects with alpha index between -0.3 and 0.3
FS? = flat spectrum objects with (Ks-[24]) colour between 6.75 and 8.31
(Sect. 3.1.3)
III = field stars and/or diskless YSOs (Class III)
(II) = Class II objects found based on WISE photometry in case of lack
Spitzer photometry (see Sect. 3.3)
Note (4): Spectral index alpha calculated from the slope of the linear fit
to the fluxes between the Ks and IRAC 8um band (Lada et al.,
2006AJ....131.1574L 2006AJ....131.1574L).
alpha > 0.3 ⟹ Class I YSOs
-0.3 < alpha < 0.3 ==> flat spectrum objects
-1.8 < alpha < -0.3 ==> Class II YSOs
alpha < -1.8 ==> Class III objects
alpha in brackets - spectral index found based on WISE photometry
in case of lack Spitzer photometry (see Sect. 3.3).
Note (5): Variability type as follows:
CTTS = the best candidates for CTTSs: Class II stars with
EW(Hα)>10Å lying above CTTS line in (J-H)-(H-K)
diagram (Fig. 21)
CTTS* = candidates for CTTSs lying above CTTS line (Class III stars with
EW(Hα)>10Å and Class II objects having spectral index
alpha>-1.8 with photometric EW(Hα)< 0Å) or
without EW(Hα)
WTTS = candidates for WTTSs: objects with spectral index alpha←1.8
which are Class II with photometric EW(Hα)<10Å or Class III
objects with photometric 0<EW(Hα)<10Å
WTTS* = remaining objects lying above CTTS line
DSCT = candidates for delta Scuti
ECL = candidates for eclipsing binary
HAeBe = Herbig Ae/Be
HAeBe* = Herbig Ae/Be
MS = main-sequence
Note (6): The area in (J-H)-(H-K) colour-colour diagram in Fig. 21.
Note (7): Membership probability determined based on proper motions
from Gaia (cat. I/345; see Sect.4).
Note (8): Other name: the other name of the star (from GCVS, HD catalogues
or WEBDA number). The names from UKIDSS-DR6 catalogue
(Lucas et al. 2012, Cat. II/316) are shown in table2.dat.
Note (9): Spectral type or
nm: non-member (the membership determined from V-(V-Ic) diagram).
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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- 3 I3 --- Name [1/245] Star designation
5- 23 A19 --- UGPS Name of source in survey (1)
25- 30 F6.3 mag Jmag ? 2MASS J magnitude (2)
32- 37 F6.3 mag Hmag ? 2MASS H magnitude (2)
39- 44 F6.3 mag Ksmag ? 2MASS Ks magnitude (2)
46- 51 F6.3 mag JmagU ? UKIDSS J magnitude (1)
53- 58 F6.3 mag HmagU UKIDSS H magnitude (1)
60- 65 F6.3 mag KmagU UKIDSS K magnitude (1)
67- 72 F6.3 mag 3.6mag ? Spitzer/IRAC 3.6 micron band magnitude (3)
74- 79 F6.3 mag 4.5mag ? Spitzer/IRAC 4.5 micron band magnitude (3)
81- 86 F6.3 mag 5.8mag ? Spitzer/IRAC 5.8 micron band magnitude (3)
88- 93 F6.3 mag 8.0mag ? Spitzer/IRAC 8.0 micron band magnitude (3)
95- 99 F5.3 mag 24mag ? Spitzer/MIPS 24 micron band magnitude (3)
101-105 F5.2 mag r'mag ? IPHAS r' magnitude (4)
107-111 F5.2 mag i'mag ? IPHAS i' magnitude (4)
113-117 F5.2 mag Hamag ? IPHAS Hα magnitude (4)
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Note (1): UKIDSS JHK magnitudes and names of sources were taken
from Lucas et al. 2012 (Cat. II/316).
Note (2): 2MASS JHKs magnitudes were taken
from Curti et al. 2003 (Cat. II/246).
Note (3): Spitzer magnitudes were taken
from Balog et al. 2007 (Cat. J/ApJ/660/1532).
Note (4): IPHAS r'i'Hα magnitudes were taken
from Barentsen et al. 2014 (Cat. II/321).
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Acknowledgements:
Gabriela Michalska, michalska(at)astro.uni.wroc.pl
(End) Patricia Vannier [CDS] 31-May-2019