J/MNRAS/465/784 Berkeley 90. III. Cluster parameters (Marco+, 2017)
The little-studied cluster Berkeley 90. III. Cluster parameters.
Marco A., Negueruela I.
<Mon. Not. R. Astron. Soc. 465, 784 (2017)>
=2017MNRAS.465..784M 2017MNRAS.465..784M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Photometry, UBVRI ; Photometry, infrared
Keywords: stars: early-type - stars: evolution -
Hertzsprung-Russell and colour-magnitude diagrams -
open clusters and associations: individual: Berkeley 90
Abstract:
The open cluster Berkeley 90 is the home to one of the most massive
binary systems in the Galaxy, LS III +46 11, formed by two identical,
very massive stars (O3.5 If* + O3.5 If*), and a second early-O system
(LS III +46 12 with an O4.5 IV((f)) component at least). Stars with
spectral types earlier than O4 are very scarce in the Milky Way, with
no more than 20 examples. The formation of such massive stars is still
an open question today, and thus the study of the environments where
the most massive stars are found can shed some light on this topic. To
this aim, we determine the properties and characterize the population
of Berkeley 90 using optical, near-infrared and WISE photometry and
optical spectroscopy. This is the first determination of these
parameters with accuracy. We find a distance of 3.5±0.5kpc and a
maximum age of 3Ma. The cluster mass is around 1000M☉ (perhaps
reaching 1500M☉ if the surrounding population is added), and we
do not detect candidate runaway stars in the area. There is a second
population of young stars to the Southeast of the cluster that may
have formed at the same time or slightly later, with some evidence for
low-activity ongoing star formation.
Description:
We present tables with coordinates in J2000, Johnson photometry and
near-IR photometry for stars in the open cluster Berkeley 90 and a
field to the southeast of this region.
We used the imager and spectrograph Andalucia Faint Object
Spectrograph and Camera (ALFOSC) on the Nordic Optical Telescope (NOT)
at the La Palma observatory to obtain UBVR photometry on the night of
2007 July 9, and spectroscopy of 20 selected stars on the nights of
2004 October 4, 2005 October 2-4 and 2007 July 10. We also
downloaded UKIDSS (https://www.ukidss.org/archive/archive.html) images
in the JHKS filters to perform deep near-IR photometry.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 79 314 Coordinates in J2000 and UBVR photometry for all
stars in the field of Berkeley 90
tablea2.dat 62 2365 Coordinates in J2000 and near-IR photometry for
stars in the field of Berkeley 90
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 11 F5.2 s RAs Right ascension (J2000)
13 A1 --- DE- Declination sign (J2000)
14- 15 I2 deg DEd Declination (J2000)
17- 18 I2 arcmin DEm Declination (J2000)
20- 23 F4.1 arcsec DEs Declination (J2000)
25- 27 I3 --- Star The identification of the star with optical
photometry in the field of Berkeley 90
29- 34 F6.3 mag Vmag Johnson V-band magnitude
36- 40 F5.3 mag e_Vmag rms uncertainty on Vmag
42- 46 F5.3 mag B-V Johnson (B-V) colour index
48- 52 F5.3 mag e_B-V rms uncertainty on (B-V) (1)
54- 59 F6.3 mag U-B Johnson (U-B) colour index
61- 65 F5.3 mag e_U-B rms uncertainty on (U-B) (1)
67- 71 F5.3 mag V-R Johnson (V-R) colour index
73- 77 F5.3 mag e_V-R rms uncertainty on (V-R) (1)
79 I1 --- N Number of measurements for each star
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Note (1): The error assigned is the standard deviation for stars with more than
one measurement and the photometric errors from DAOPHOT for stars with only
one measurement, with the errors in the colour indices calculated through
error propagation.
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 11 F5.2 s RAs Right ascension (J2000)
13 A1 --- DE- Declination sign (J2000)
14- 15 I2 deg DEd Declination (J2000)
17- 18 I2 arcmin DEm Declination (J2000)
20- 23 F4.1 arcsec DEs Declination (J2000)
25- 30 F6.3 mag Jmag UKIDSS J magnitude in 2MASS photometric system
32- 36 F5.3 mag e_Jmag rms uncertainty on Jmag (1)
38- 43 F6.3 mag Hmag UKIDSS H magnitude in 2MASS photometric system
45- 49 F5.3 mag e_Hmag rms uncertainty on Hmag (1)
51- 56 F6.3 mag Ksmag UKIDSS Ks magnitude in 2MASS photometric system
58- 62 F5.3 mag e_Ksmag rms uncertainty on Ksmag (1)
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Note (1): The error assigned is the the photometric errors from DAOPHOT,
because the number of measurements is only one for each filter.
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Acknowledgements:
Amparo Marco, amparo.marco(at)ua.es
References:
Maiz Apellaniz et al., Paper I 2015A&A...579A.108M 2015A&A...579A.108M
Maiz Apellaniz et al., Paper II 2015A&A...583A.132M 2015A&A...583A.132M
(End) Patricia Vannier [CDS] 11-Jan-2017