J/MNRAS/447/3973 UKIRT M33 monitoring project. IV. WFCAM obs. (Javadi+, 2015)
The UK Infrared Telescope M33 monitoring project
IV. Variable red giant stars across the Galactic disc.
Javadi A., Saberi M., Van Loon J.TH., Khosroshahi H., Golabatooni N.,
Mirtorabi M.T.
<Mon. Not. R. Astron. Soc. 447, 3973 (2015)>
=2015MNRAS.447.3973J 2015MNRAS.447.3973J (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby; Photometry, infrared; Stars, variable
Keywords: stars: evolution; stars: luminosity function, mass function;
stars: mass-loss; stars: oscillations; galaxies: individual: M33;
galaxies: stellar content
Abstract:
We have conducted a near-infrared monitoring campaign at the UK
InfraRed Telescope, of the Local Group spiral galaxy M33 (Triangulum).
The main aim was to identify stars in the very final stage of their
evolution, and for which the luminosity is more directly related to
the birth mass than the more numerous less-evolved giant stars that
continue to increase in luminosity. In this fourth paper of the
series, we present a search for variable red giant stars in an almost
square degree region comprising most of the galaxy's disc, carried out
with the WFCAM (Wide Field CAMera) instrument in the K band. These
data, taken during the period 2005-2007, were complemented by J- and
H-band images. Photometry was obtained for 403 734 stars in this
region; of these, 4643 stars were found to be variable, most of which
are asymptotic giant branch (AGB) stars. The variable stars are
concentrated towards the centre of M33, more so than low-mass,
less-evolved red giants. Our data were matched to optical catalogues
of variable stars and carbon stars and to mid-infrared photometry from
the Spitzer Space Telescope. Most dusty AGB stars had not been
previously identified in optical variability surveys, and our survey
is also more complete for these types of stars than the Spitzer
survey.
Description:
Observations were made with three of UK InfraRed Telescope (UKIRT)'s
imagers: UIST, UFTI, and Wide Field CAMera (WFCAM). UIST and UFTI
cover the central part (∼1kpc2) and the photometry, star formation
history, and mass return in this region was explained in Papers I
(Javadi+ 2011, J/MNRAS/411/263), II (Javadi+ 2011MNRAS.414.3394J 2011MNRAS.414.3394J), and
III (Javadi+ 2013MNRAS.432.2824J 2013MNRAS.432.2824J). In this sequel, we focus on the
data from WFCAM, which cover a much larger part of M33.
The monitoring campaign comprises observations with the WFCAM such
that four separately pointed observations ("tiles", viz. M33-1, M33-2,
M33-3, and M33-4) may be combined to cover a filled square area of sky
covering 0.89deg2 (13kpcx13kpc) at a pixel size of 0.4".
Observations were made in the K band (UKIRT filter K98) over the
period 2005 September-2007 October. On some occasions, observations
were made also in the J band and/or H band (UKIRT filters J98 and H98,
respectively). The number of epochs varies per tile between five and
eight, but overlapping regions will have been observed more frequently.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
01 33 50.89 +30 39 36.6 M33 = NAME Triangulum Galaxy
----------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
wfcam.dat 126 403733 The UKIRT/WFCAM photometric catalog
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See also:
VII/233 : 2MASS All-Sky Extended Source Catalog (XSC) (IPAC/UMass, 2003-2006)
J/AJ/121/861 : BVI photometry of central part of M33 (Macri+, 2001)
J/AJ/121/2032 : Direct variables in M33A field (Mochejska+, 2001)
J/AJ/122/2477 : DIRECT variables in M33B field (Mochejska+, 2001)
J/ApJS/149/343 : Giant molecular clouds in M33 (Engargiola+, 2003)
J/A+A/426/11 : XMM-Newton survey of M33 (Pietsch+, 2004)
J/AJ/129/729 : CCD photometry of luminous stars in M33 (Rowe+, 2005)
J/AJ/131/2478 : M31 and M33 UBVRI photometry (Massey+, 2006)
J/AJ/132/1361 : RR Lyrae variables in M33 (Sarajedini+, 2006)
J/MNRAS/370/1429 : V photometry of bright stars of M33 (Shporer+, 2006)
J/MNRAS/371/1405 : Variables in M33 (Hartman+, 2006)
J/A+A/458/225 : Phot. standard stars in the field of GR 290 (Viotti+, 2006)
J/ApJ/652/313 : BV phot. of a detached EB in M 33 (Bonanos+, 2006)
J/ApJ/664/850 : Spitzer observations of stars in M33 (McQuinn+, 2007)
J/MNRAS/382/1353 : Spectral atlas of omega Cen post-MS stars (van Loon+, 2007)
J/A+A/487/131 : JHKs photometry of LPVs in M33 (Cioni+, 2008)
J/ApJ/705/1364 : MIR catalog of point sources in M33 (Thompson+, 2009)
J/MNRAS/411/263 : Paper I - JHK variable stars in M33 (Javadi+ 2011)
J/ApJ/750/97 : The yellow and red supergiants of M33 (Drout+, 2012)
J/ApJ/790/48 : Variable stars in M31 & M33. II. LBVs (Humphreys+, 2014)
J/AJ/154/81 : BVRI phot. of luminous stars in M31 and M33 (Martin+, 2017)
J/ApJS/253/53 : PHATTER. I. 22million stars in M33 with HST (Williams+, 2021)
J/AJ/165/137 : Light curve and observed properties in M33 (Ou+, 2023)
Byte-by-byte Description of file: wfcam.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- ID [1/417719] Star number
8- 13 I6 --- ID-J [1/276973]?=0 Star id in J
15- 20 I6 --- ID-H [1/301064]?=0 Star id in H
22- 27 I6 --- ID-K [1/369248]?=0 Star id in K
29- 30 I2 --- Nj [0/10] Number of J-band measurements
32 I1 --- Nh [0/8] Number of H-band measurements
34- 35 I2 --- Nk [0/24] Number of K-band measurements
37- 44 F8.6 deg RAdeg [0.4/0.42] Right ascension (J2000)
46- 53 F8.6 deg DEdeg [0.5/0.55] Declination (J2000)
55- 60 F6.3 mag Jmag [9.6/22.6]?=99.999 Mean UKIRT/WFCAM J-band
magnitude
62- 67 F6.4 mag e_Jmag [0.008/0.7]?=9.9999 Uncertainty in Jmag
69- 74 F6.3 mag Hmag [10/22.1]?=99.999 Mean UKIRT/WFCAM H-band
magnitude
76- 81 F6.4 mag e_Hmag [0.003/0.8]?=9.9999 Uncertainty in Hmag
83- 88 F6.3 mag Kmag [9/22]?=99.999 Mean UKIRT/WFCAM K band
magnitude
90- 95 F6.4 mag e_Kmag [0.005/0.8]?=9.9999 Uncertainty in Kmag
97- 103 F7.3 --- Var-J [-53.8/130.2] Variability index, J
105- 109 F5.3 --- Kurt-K [0/1] Kurtosis index, K
111- 116 F6.3 --- Var-L [-2.4/29.4] Variability index, L (1)
118- 121 F4.1 --- Weight [0/22] Weight
123- 126 F4.1 --- TWeight [7/24] Total weight
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Note (1): The variability index L (Stetson 1996PASP..108..851S 1996PASP..108..851S):
L=(JxK)/0.798x(Σw/wall) -- Equation (4)
where Σw is the total weight assigned to a given star and
wall is the total weight a star would have if observed in every
single observation. See Equation (2) for the J index and (3) for the
Kurtosis index K.
The long period variables have index L>1.5
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Acknowledgements:
Atefeh Javadi [atefeh at ipm.ir]
References:
Javadi et al. Paper I. 2011MNRAS.411..263J 2011MNRAS.411..263J Cat. J/MNRAS/411/263
Javadi et al. Paper II. 2011MNRAS.414.3394J 2011MNRAS.414.3394J
Javadi et al. Paper III. 2013MNRAS.432.2824J 2013MNRAS.432.2824J
Javadi et al. Paper IV. 2015MNRAS.447.3973J 2015MNRAS.447.3973J This catalog
(End) Emmanuelle Perret [CDS] 09-Sep-2025