J/MNRAS/411/263 JHK variable stars in M33 (Javadi+ 2011)
The UK Infrared Telescope M 33 monitoring project.
I. Variable red giant stars in the central square kiloparsec.
Javadi A., van Loon J.T., Mirtorabi M.T.
<Mon. Not. R. Astron. Soc. 411, 263 (2011)>
=2011MNRAS.411..263J 2011MNRAS.411..263J
ADC_Keywords: Stars, variable ; Galaxies, nearby ; Photometry, infrared
Keywords: stars: evolution - stars: luminosity function, mass function -
stars: mass-loss - stars: oscillations - galaxies: individual: M 33 -
galaxies: stellar content
Abstract:
We have conducted a near-infrared monitoring campaign at the UK
InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M 33
(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. The most
extensive dataset was obtained in the K-band with the UIST instrument
for the central 4'x4' (1kpc2) --- this contains the nuclear star
cluster and inner disc. These data, taken during the period
2003-2007, were complemented by J- and H-band images. Photometry was
obtained for 18,398 stars in this region; of these, 812 stars were
found to be variable, most of which are Asymptotic Giant Branch (AGB)
stars. Our data were matched to optical catalogues of variable stars
and carbon stars, and to mid-infrared photometry from the Spitzer
Space Telescope.
In this first of a series of papers, we present the methodology of
the variability survey and the photometric catalogue, which is made
publicly available at the Centre de Donnees astronomiques de
Strasbourg (CDS), and discuss the properties of the variable
stars. 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 WFCAM. The WFCAM observations cover a much
larger part of M33 and are discussed in Paper IV of this series.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
m33p1.dat 128 18398 Photometric catalog.
Part I: stellar mean properties
m33p2.dat 52 356303 Photometric catalog. Part II: multi-epoch data
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See also:
J/A+A/373/438 : X-ray view of M33 after ROSAT (Haberl+, 2001)
J/A+A/426/11 : XMM-Newton survey of M33 (Pietsch+, 2004)
J/A+A/448/1247 : XMM-Newton survey of M33 (Misanovic+, 2006)
J/AJ/131/2478 : M31 and M33 UBVRI photometry (Massey+, 2006)
J/A+A/472/785 : Radio continuum survey of M33 (Tabatabaei+, 2007)
J/A+A/476/1161 : Spitzer photometry of M33 (Verley+, 2007)
J/ApJ/664/850 : Spitzer observations of stars in M33 (McQuinn+, 2007)
J/ApJS/174/366 : Chandra ACIS survey of M33 (ChaSeM33) (Plucinsky+, 2008)
Byte-by-byte Description of file: m33p1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq [3/19600] Star number
6- 7 I2 h RAh Right Ascension J2000 (hours)
8 A1 --- --- [:]
9- 10 I2 min RAm Right Ascension J2000 (minutes)
11 A1 --- --- [:]
12- 17 F6.3 s RAs Right Ascension J2000 (seconds)
18 A1 --- DE- Declination J2000 (sign)
19- 20 I2 deg DEd Declination J2000 (degrees)
21 A1 --- --- [:]
22- 23 I2 arcmin DEm Declination J2000 (minutes)
24 A1 --- --- [:]
25- 29 F5.2 arcsec DEs Declination J2000 (seconds)
31- 36 F6.3 mag Jmag ?=99.999 Mean J-band magnitude (UKIRT J[98])
38- 43 F6.4 mag e_Jmag ?=9.9999 Error in Jmag
45- 50 F6.3 mag Hmag ?=99.999 Mean H-band magnitude (UKIRT H[98])
52- 57 F6.4 mag e_Hmag ?=9.9999 Error in Hmag
59- 64 F6.3 mag Kmag Mean K-band magnitude (UKIRT K[98])
66- 71 F6.4 mag e_Kmag Error in Kmag
75- 76 I2 --- o_Jmag Number of J-band measurements
80- 81 I2 --- o_Hmag Number of H-band measurements
85- 86 I2 --- o_Kmag Number of K-band measurements
89- 93 F5.3 --- chi Mean χ value from DAOphot
95-100 F6.3 --- sharp Mean sharpness value from DAOphot (G1)
102-107 F6.3 --- Jvar Variability index J (2)
109-114 F6.3 --- Kvar [0/1] Kurtosis index K (2)
116-121 F6.3 --- Lvar Variability index L (2)
123-128 F6.3 mag Kamp ?=99.999 Estimated K-band amplitude
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Note (2): see section 4 of the paper.
* Jvar is close to zero for data containing random noise only
* Kvar depends on the shape of the light curve (K=0.9 for sinusoidal
light variation; K=0.798 for a Gaussian distribution (i.e. random
noise); and K->0 for data affected by a single outlier.
* Lvar is defined as J.K/0.798, i.e. is large for variable
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Byte-by-byte Description of file: m33p2.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq [3/19600] Star number
7- 15 F9.4 d Epoch Epoch (HJD-2450000)
20 A1 --- F [JHK] Filter (J, H or K)
23- 28 F6.3 mag mag Magnitude observed in filter F
31- 36 F6.4 mag e_mag Error in magnitude
40- 43 F4.2 --- chi χ value from DAOphot
44 A1 --- --- [0]
47- 52 F6.3 --- sharp Sharpness value from DAOphot (G1)
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Global Notes:
Note (G1): the "sharp" parameter is close to zero for isolated stars;
significantly negative for bad pixels and cosmic rays; significantly
positive for blended or non-stellar objects.
Acknowledgements:
Jacco van Loon, acco(at)astro.keele.ac.uk
(End) Patricia Vannier [CDS] 21-Sep-2010