J/MNRAS/435/429 Berkeley 94 and Berkeley 96 UBVRcIcJHKs (Delgado+, 2013)
Berkeley 94 and Berkeley 96:
two young clusters with different dynamical evolution.
Delgado A.J., Djupvik A.A, Costado M.T., Alfaro E.J.
<Mon. Not. R. Astron. Soc. 435, 429 (2013)>
=2013MNRAS.435..429D 2013MNRAS.435..429D
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Photometry, UBVRI ;
Photometry, infrared
Keywords: open clusters and associations: individual: Berkeley 94 -
open clusters and associations: individual: Berkeley 96 -
stars: pre-main sequence
Abstract:
We have performed multiband UBVRcIcJHKs photometry of two young
clusters located at large Galactocentric distances in the direction of
the Perseus spiral arm. The obtained distances and colour excesses
amount to 3.9±0.11kpc, E(B-V)=0.62±0.05 for Berkeley 94, and
4.3±0.15kpc, E(B-V)=0.58±0.06 for Berkeley 96. The respective
ages, as measured from the comparison of the upper colour-magnitude
diagrams to model isochrones, amount to log10Age(yr)=7.5±0.07 and
7.0±0.07, respectively. A sequence of optical pre-main-sequence
(PMS) members is proposed in both clusters. In addition, samples of
objects showing (H-Ks) excess are found. Part of these are suggested
to be PMS cluster members of lower mass than the optical candidates.
The spatial distribution of these sources, the comparison to Galactic
models and to the expected number of contaminating distant red
galaxies, and the spectral energy distribution in particular cases
support this suggestion. The spatial distributions shown by members in
different mass ranges can be interpreted in terms of the results from
numerical simulations. According to these, different initial
conditions and evolutionary dynamical paths are suggested for the
clusters. Berkeley 94 would have formed under supervirial conditions,
and followed the so-called warm collapse model in its evolution,
whereas Berkeley 96 would have formed with a subvirial structure, and
would have evolved following a cold collapse path. Both processes
would be able to reproduce the suggested degree of mass segregation
and their spatial distribution by mass range. Finally, the mass
distributions of the clusters, from the most massive stars down to PMS
stars around 1.3M☉, are calculated. An acceptable general
agreement with the Salpeter initial mass function slope is found.
Description:
Photometry in the UBVRcIcJHKs bands is presented for 5908 stars in the
fields of the two Galactic young open clusters Berkeley 94 and
Berkeley 96. The 2MASS identity is included for those stars with
detected 2MASS counterpart. MS, post-MS and PMS candidate members are
identified in the forelast column. Sources with detected NIR excess
are also indicated in the last column.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 171 5908 UBVRcIcJHKs photometric indices
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Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [Be]
3- 4 I2 --- Be [94/96] Berkeley cluster number (94 or 96)
7- 10 I4 --- N Identification number within the cluster
(this work)
13- 28 A16 --- 2MASS Identification in 2MASS (blank if not in 2MASS)
31- 40 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
43- 51 F9.6 deg DEdeg Declination in decimal degrees (J2000)
54- 58 F5.2 mag Vmag ?=99.99 Johnson V magnitude (2)
61- 65 F5.2 mag e_Vmag ?=99.99 Error in V (2)
68- 72 F5.2 mag U-B ?=99.99 Johnson U-B colour index (2)
75- 79 F5.2 mag e_U-B ?=99.99 Error in U-B (2)
82- 86 F5.2 mag B-V ?=99.99 Johnson B-V colour index (2)
89- 93 F5.2 mag e_B-V ?=99.99 Error in B-V (2)
96-100 F5.2 mag V-Rc ?=99.99 Johnson-Cousins V-Rc colour index (2)
103-107 F5.2 mag e_V-Rc ?=99.99 Error in V-Rc (2)
110-114 F5.2 mag V-Ic ?=99.99 Johnson-Cousins V-Ic colour index (2)
117-121 F5.2 mag e_V-Ic ?=99.99 Error in V-Ic (2)
124-128 F5.2 mag Ksmag ?=99.99 2MASS Ks magnitude (2)
131-135 F5.2 mag e_Ksmag ?=99.99 Error in Ks (2)
138-142 F5.2 mag J-H ?=99.99 2MASS J-H colour index (2)
145-149 F5.2 mag e_J-H ?=99.99 Error in J-H (2)
152-156 F5.2 mag H-Ks ?=99.99 H-Ks colour index (2)
159-163 F5.2 mag e_H-Ks ?=99.99 2MASS Error in H-Ks (2)
167 I1 --- Mm [0/3] Membership assignment, 0=non-member (3)
170-171 I2 --- IRe [-1/1] Near-IR excess status, 1 for excess (4)
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Note (2): A 99.99 entry indicates a non-detection.
Note (3): Membership assignment is numbered as follows:
0 = not member
1 = main-sequence (MS) and post-main-sequence (postMS) member
2 = optical pre-main sequence (PMS) members
3 = PMSR members, as defined in the article (reduced PMS members sample)
Note (4): NIR excess as follows:
-1 = no measurement
0 = no excess
1 = NIR excess source
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Acknowledgements:
Antonio Jesus Delgado, delgado(at)iaa.es
(End) Antonio Delgado [IAA-CSIC, Spain], Patricia Vannier [CDS] 24-Sep-2013