J/MNRAS/477/2976 Berkeley 51 UBV photometry (Negueruela+, 2018)
Berkeley 51, a young open cluster with four yellow supergiants.
Negueruela I., Monguio M., Marco A., Tabernero H.M., Gonzalez-fernandez C.,
Dorda R.
<Mon. Not. R. Astron. Soc., 477, 2976-2990 (2018)>
=2018MNRAS.477.2976N 2018MNRAS.477.2976N (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Populations, stellar ; Photometry, UBV ;
MK spectral classification
Keywords: stars: evolution; supergiants -
open clusters and associations: individual: Berkeley 51
Abstract:
The heavily obscured open cluster Berkeley 51 shows characteristics
typical of young massive clusters, even though the few previous
studies have suggested older ages. We combine optical (UBV) and 2MASS
photometry of the cluster field with multi-object and long-slit
optical spectroscopy for a large sample of stars. We apply classical
photometric analysis techniques to determine the reddening to the
cluster, and then derive cluster parameters via isochrone fitting. We
find a large population of B-type stars, with a main-sequence turn-off
at B3 V, as well as a large number of supergiants with spectral types
ranging from F to M. We use intermediate-resolution spectra of the
evolved cool stars to derive their stellar parameters and find an
essentially solar iron abundance. Under the plausible assumption that
our photometry reaches stars still close to the zero-age main
sequence, the cluster is located at d≃5.5kpc and has an age
of ∼60Ma, though a slightly younger and more distant cluster
cannot be ruled out. Despite the apparent good fit of isochrones,
evolved stars seem to reside in positions of the colour-magnitude
diagram far away from the locations where stellar tracks predict
helium burning to occur. Of particular interest is the presence of
four yellow supergiants, two on the ascending branch and two others
close to or inside the instability strip.
Description:
UBV photometry of Be 51 was obtained in service mode using Andalucia
Faint Object Spectrograph and Camera (ALFOSC) on the Nordic Optical
Telescope (NOT) at the Roque de los Muchachos Observatory (La Palma,
Spain) on the night of 2008 September 19.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 127 240 Coordinates, UBV photometry, 2MASS identification
and 2MASS JHKS photometry for all stars in the
field of Berkeley 51
table3.dat 63 12 *Stellar parameters for cool stars in the field
of Be 51.
table4.dat 27 32 Intrinsic parameters for all very likely
photometric members, ordered by dereddened
magnitude
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Note on table3.dat: The top panel lists stars in the central condensation that
are considered likely members. The bottom panel presents two other stars at
higher distances.
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Byte-by-byte Description of file: tableb1.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 --- Name [1/285] Star identification number
29- 34 F6.3 mag Vmag V magnitude
36- 40 F5.3 mag e_Vmag rms uncertainty on Vmag
42- 46 F5.3 mag B-V B-V colour index
48- 52 F5.3 mag e_B-V rms uncertainty on B-V
54- 59 F6.3 mag U-B U-B colour index
61- 65 F5.3 mag e_U-B rms uncertainty on U-B
67 I1 --- n Number of measurements in UBV
69- 84 A16 --- 2MASS 2MASS designation (HHMMSSss+DDMMSSs)
86- 91 F6.3 mag Jmag ?=- 2MASS J magnitude
93- 97 F5.3 mag e_Jmag ?=- rms uncertainty on Jmag
99-104 F6.3 mag Hmag ?=- 2MASS H magnitude
106-110 F5.3 mag e_Hmag ?=- rms uncertainty on Hmag
112-117 F6.3 mag Ksmag ?=- 2MASS Ks magnitude
119-123 F5.3 mag e_Ksmag ?=- rms uncertainty on Ksmag
125-127 A3 --- Flag 2MASS quality flags
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Name Star identification number
5- 12 A8 --- SpType Spectral type (1)
14- 24 A11 "date" Date Observation date
26- 29 I4 K Teff ?=- Effective temperature
31- 33 I3 K e_Teff ?=- rms uncertainty on Teff
35- 37 F3.1 [cm/s2] logg ?=- Surface gravity
39- 42 F4.2 [-] [M/H] ?=- Metallicity
44- 47 F4.2 [-] e_[M/H] ?=- rms uncertainty on [M/H]
49- 52 F4.2 km/s vt ?=- Microturbulent velocity
54- 55 I2 Msun MARCS ?=- MARCS grid
57- 59 I3 km/s vhel Heliocentric velocity
61- 63 I3 km/s vLSR LSR velocity
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Note (1): Spectral type in the spectrum analysed. It appears decidedly later
in the lower resolution spectrum taken in 2007.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Name Star identification number
5- 10 A6 ---- SpTypePh Photometric spectral type (1)
13- 21 A9 --- SpType Spectral type (when available) (2)
23- 26 F4.2 mag E(B-V) Reddening
27 A1 --- n_E(B-V) [bc] Note on E(B-V) (3)
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Note (1): Spectral types are derived from the photometry following the procedure
described in the text, under the assumption of µ=13.7.
Note (2): Spectral types are given for the 10 stars observed with GTC/OSIRIS
and also for Star No 103.
Note (3): Notes as follows:
b = Colour excess values for the confirmed Be star are not entirely
interstellar
c = Derived from the Z-band spectrum, and so less certain
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 09-Jun-2021