J/A+A/364/455 ubvy photometry of LMC/SMC B stars (Larsen+, 2000)
Reddenings and metallicities in the LMC and SMC from Stroemgren CCD photometry.
Larsen S.S., Clausen J.V., Storm J.
<Astron. Astrophys. 364, 455 (2000)>
=2000A&A...364..455L 2000A&A...364..455L
ADC_Keywords: Magellanic Clouds ; Stars, B-type ; Photometry, CCD ;
Photometry, uvby
Keywords: galaxies: abundances - galaxies: ISM - galaxies: Magellanic Clouds -
galaxies: photometry
Abstract:
The individual reddenings for B stars in two fields in the Small
Magellanic Cloud (SMC) and two fields in the Large Magellanic Cloud
(LMC) are determined by means of Stroemgren uvby CCD photometry. In
both LMC fields we find a foreground reddening of E(B-V)=0.085±0.02,
and for the SMC fields we find E(B-V)=0.070±0.02. In addition to the
foreground reddening we find contributions from reddening
intrinsically in the Clouds up to E(B-V)∼0.21. The intrinsic
contribution is not correlated with position within our ∼6'x4.5' CCD
fields but varies in an essentially random way. Unless the reddening
is measured for a particular object, it will be uncertain by ±0.035
(best case, far from the central bars) to more than ±0.10 (close to
the central bars). The Stroemgren uvby photometry has been used to
derive metallicities for GK giant stars in the observed fields.
Adopting average reddenings we obtain mean metallicities which are
consistent with those found from spectroscopic studies of F and G
supergiants (Westerlund, 1997, The Magellanic Clouds, Cambridge
University Press), but with a considerable scatter in the derived
metallicities, from [Fe/H]≃-2.0 to [Fe/H]>0. A significant fraction
of the scatter is, however, due to reddening variations rather than
being intrinsic. The possible existence of high metallicity stars
should be investigated further using spectroscopic methods.
Description:
These tables list Stroemgren uvby photometry for 2 CCD fields in the
Large Magellanic Cloud and 2 CCD fields in the Small Magellanic Cloud.
The data were obtained with the Danish 1.54 meter telescope at ESO, La
Silla.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tab982.dat 127 8888 Data for HV 982 field (LMC)
tab1433.dat 127 11838 Data for HV 1433 field (SMC)
tab11284.dat 127 12646 Data for HV 11284 field (SMC)
tab12578.dat 127 5367 Data for HV 12578 field (LMC)
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Byte-by-byte Description of file: tab*.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq Stars sequential number
7- 12 F6.1 pix xpos CCD X coordinate
14- 19 F6.1 pix ypos CCD Y coordinate
21- 22 I2 h RAh Right ascension (J2000)
24- 25 I2 min RAm Right ascension (J2000)
27- 31 F5.2 s RAs Right ascension (J2000)
33 A1 --- DE- Declination sign (J2000)
34- 35 I2 deg DEd Declination (J2000)
37- 38 I2 arcmin DEm Declination (J2000)
40- 43 F4.1 arcsec DEs Declination (J2000)
45- 49 F5.2 mag Vmag V magnitude from Stroemgren y band
51- 56 F6.3 mag b-y (b-y) colour index
58- 63 F6.3 mag m1 ?=-9.990 m1 colour index (1)
65- 70 F6.3 mag c1 ?=-9.990 c1 colour index (1)
72- 77 F6.3 mag e_Vmag Vmag error
79- 84 F6.3 mag e_b-y (b-y) error
86- 91 F6.3 mag e_m1 ?=-9.990 (m1) error (1)
93- 98 F6.3 mag e_c1 ?=-9.990 (c1) error (1)
101-105 F5.2 --- 2_ymag Chi-Square (y)
108-112 F5.2 --- 2_bmag Chi-Square (b)
114-119 F6.2 --- 2_vmag ?=-99.99 Chi-Square (v) (1)
121-126 F6.2 --- 2_umag ?=-99.99 Chi-Square (u) (1)
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Note (1):
The values -9.99 (Stroemgren indices, errors) or -99.99 (chi-square)
indicate that the corresponding quantity could not be measured.
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Acknowledgements: Soeren Larsen
(End) Patricia Bauer [CDS] 26-Feb-2001