J/A+A/459/871 Chemically peculiar stars in the LMC (Paunzen+, 2006)
Chemically peculiar stars in the Large Magellanic Cloud
Paunzen E., Maitzen H.M., Pintado O.I., Claret A., Iliev I.K., Netopil M.
<Astron. Astrophys. 459, 871 (2006)>
=2006A&A...459..871P 2006A&A...459..871P
ADC_Keywords: Magellanic Clouds ; Stars, peculiar ; Stars, early-type ;
Photometry, UBVRI ; Photometry, narrow-band
Keywords: galaxies: Magellanic Clouds - stars: chemically peculiar -
stars: early-type - techniques: photometric
Abstract:
We present high precision photometric Delta a observations of 417
objects in NGC 2136/7 and its surrounding field, of which five turned
out to be bona fide magnetic CP stars. In addition, we discovered two
Be/Ae stars. This intermediate band photometric system samples the
depth of the 520nm flux depression by comparing the flux at the
center with the adjacent regions with bandwidths of 11nm to 23nm.
The Delta a photometric system is most suitable for detecting CP2
stars with high efficiency, but is also capable of detecting a small
percentage of non-magnetic CP objects. From our investigations
of NGC 1711, NGC 1866, NGC 2136/7, their surroundings, and one
independent field of the LMC population, we derive an occurrence
of classical chemically peculiar stars of 2.2(6)% in the LMC, which
is only half the value found in the Milky Way. The mass and age
distribution of the photometrically detected CP stars is not different
from that of similar objects in galactic open clusters.
Description:
Photometric CCD Delta a measurements of objects within the LMC cluster
NGC 2136/7 and its surrounding were obtained at CASLEO and ESO-La Silla.
Object:
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RA (2000) DE Designation(s)
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05 53 17 -69 31.7 NGC 2136/7 = NGC 2136
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 132 417 Observed program stars in NGC 2136/7 and
its surrounding
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1,417] Stars number sorted after X and Y
5- 13 F9.6 h RAhr Right Ascension (J2000.0)
15- 23 F9.5 deg DEdeg Declination (J2000.0)
25- 30 F6.1 pix Xpos X coordinate
32- 34 F3.1 pix e_Xpos rms uncertainty on X coordinate
36- 41 F6.1 pix Ypos Y coordinate
43- 45 F3.1 pix e_Ypos rms uncertainty on Y coordinate
47- 52 F6.3 mag g1-y Mean (g1-y) index
54- 58 F5.3 mag e_g1-y rms uncertainty on (g1-y)
60- 65 F6.3 mag Da ? Deviation from cluster line (Delta a)
67- 71 F5.3 mag a ? Mean a index (a=g2-[(g1+y)/2])
73- 77 F5.3 mag e_a ? rms uncertainty on a
79- 84 F6.3 mag Umag ? Johnson U magnitude (1)
86- 90 F5.3 mag e_Umag ? rms uncertainty on U magnitude
92- 97 F6.3 mag Bmag ? Johnson B magnitude (1)
99-103 F5.3 mag e_Bmag ? rms uncertainty on B magnitude
105-110 F6.3 mag Vmag ? Johnson V magnitude (1)
112-116 F5.3 mag e_Vmag ? rms uncertainty on V magnitude
118-123 F6.3 mag Imag ? Johnson I magnitude (1)
125-129 F5.3 mag e_Imag ? rms uncertainty on I magnitude
131-132 I2 --- N [10,69] Number of measurements
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Note (1): Magnitudes from Zaritsky et al., 2004AJ....128.1606Z 2004AJ....128.1606Z.
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Acknowledgements:
Ernst Paunzen, ernst.paunzen(at)univie.ac.at
(End) Ernst Paunzen [Vienna, Austria], Patricia Vannier [CDS] 05-Mar-2007