J/A+A/631/A124 NGC 2345 Stroemgren photometry (Alonso-Santiago+, 2019)
A comprehensive study of NGC 2345, a young open cluster with a low metallicity.
Alonso-Santiago J., Negueruela I., Marco A., Tabernero H.M.,
Gonzalez-Fernandez C., Castro N.
<Astron. Astrophys. 631, A124 (2019)>
=2019A&A...631A.124A 2019A&A...631A.124A (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Photometry, uvby ; Photometry, infrared
Keywords: open clusters and associations: individual: NGC 2345 -
Hertzsprung-Russel and C-M diagrams - stars: abundances -
stars: fundamental parameters - stars: late-type -
stars: emission-line, Be
Abstract:
NGC 2345 is a young open cluster hosting seven blue and red
supergiants, low metallicity and a high fraction of Be stars which
makes it a privileged laboratory to study stellar evolution. We aim to
improve the determination of the cluster parameters and study the Be
phenomenon. Our objective is also to characterise its seven evolved
stars by deriving their atmospheric parameters and chemical
abundances. We performed a complete analysis combining for the first
time ubvy photometry with spectroscopy as well as Gaia Data Release 2.
We obtained spectra with classification purposes for 76 stars and
high-resolution spectroscopy for an in-depth analysis of the blue and
red evolved stars. We identify a new red supergiant and 145 B-type
likely members within a radius of 18.7±1.2arcmin, which implies an
initial mass, Mcl∼5,200M☉. We find a distance of 2.5±0.2kpc
for NGC 2345, placing it at RGC=10.2±0.2kpc. Isochrone fitting
supports an age of 56±13Ma, implying masses around 6.5M☉ for
the supergiants. A high fraction of Be stars (∼10%) is found. From the
spectral analysis we estimate for the cluster an average
vrad=+58.6±0.5km/1 and a low metallicity, [Fe/H]=-0.28±0.07. We
also have determined chemical abundances for Li, O, Na, Mg, Si, Ca,
Ti, Ni, Rb, Y, and Ba for the evolved stars. The chemical composition
of the cluster is consistent with that of the Galactic thin disc. One
of the K supergiants, S50, is a Li-rich star, presenting an A(Li)∼2.1.
An overabundance of Ba is found, supporting the enhanced s-process.
NGC 2345 has a low metallicity for its Galactocentric distance,
comparable to typical LMC stars. It is massive enough to serve as a
testbed for theoretical evolutionary models for massive
intermediate-mass stars.
Description:
The ubvy Stroemgren photometry for 2153 stars in the field of NGC 2345
was obtained using the Wide Field Camera (WFC) on the 2.5-m Isaac
Newton Telescope (INT) at the El Roque de los Muchachos Observatory,
located in the Canarian island of La Palma (Spain). The observations
were acquired during the nights of 2011 December 23-25.
Spectra for 76 stars in the field of NGC 2345 were obtained in several
runs, from 2010 to 2016, with different spectrographs (see Table A.2).
The sample consists of 32 photometric cluster members, according to
Moffat (1974), as well as early-type stars and supergiants in the
surroundings of the cluster in order to study its extent.
For the analysis, photometric and spectroscopic data were complemented
by Gaia DR2 astrometry.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 97 2153 Stroemgren photometry of NGC 2345
tablea2.dat 72 76 For every star with spectroscopy the equatorial
coordinates, spectral type, radial velocity
(from the AA{OMEGA} spectrum), spectrographs used,
and cluster membership are displayed.
tablea3.dat 63 83 Gaia DR2 astrometric data for all stars in field of
NGC 2345 for which we have spectra and other
objects discussed in text
tablea4.dat 78 145 Photometric and astrometric data for likely
blue members
--------------------------------------------------------------------------------
See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- ID [1/2153] ID number
7- 19 F13.9 deg RAdeg Right ascension (J2000)
22- 34 F13.9 deg DEdeg Declination (J2000)
37- 42 F6.3 mag Vmag Calibrated Johnson V-magnitude band
45- 49 F5.3 mag e_Vmag rms uncertainty on Vmag
52- 57 F6.3 mag b-y Stroemgren (b-y) colour index
60- 64 F5.3 mag e_b-y rms uncertainty on (b-y)
67- 72 F6.3 mag m1 Stroemgren m1 index
75- 79 F5.3 mag e_m1 rms uncertainty on m1
82- 87 F6.3 mag c1 Stroemgren c1 index
90- 94 F5.3 mag e_c1 rms uncertainty on c1
97 I1 --- N Number of measurements for each star
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Star Star name
9- 12 I4 --- ID ? ID number
17- 29 F13.9 deg RAdeg Right ascension (J2000)
31- 43 F13.9 deg DEdeg Declination (J2000)
45- 56 A12 --- SpType Spectral type
58- 59 I2 km/s RV ? Radial velocity from the AA spectrum
61 A1 --- AAO [*-] *: AA{OMEGA} spectrograph used
63 A1 --- WYFFOS [*-] *: WYFFOS spectrograph used
65 A1 --- FEROS [*-] *: FEROS spectrograph used
67 A1 --- ISIS [*-] *: ISIS spectrograph used
69 A1 --- IDS [*-] *: IDS spectrograph used
71- 72 A2 --- Member Cluster membership
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- Status Membership status (1)
4- 22 A19 --- Star Star name
24- 30 F7.4 mas plx Gaia-DR2 Parallax
32- 37 F6.4 mas e_plx Gaia-DR2 Parallax uncertainty
39- 44 F6.3 mas/yr pmRA* Gaia-DR2 Proper motion along RA, pmRA*cosDE
46- 50 F5.3 mas/yr e_pmRA* Gaia-DR2 Proper motion along RA uncertainty
52- 57 F6.3 mas/yr pmDE Gaia-DR2 Proper motion along DE
59- 63 F5.3 mas/yr e_pmDE Gaia-DR2 Proper motion along DE uncertainty
--------------------------------------------------------------------------------
Note (1): Membership status as follows:
M = Members
HM = Halo members
NM = Non members
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- ID ID number
7- 11 F5.3 mag E(B-V) Colour excess
14- 19 F6.3 mag Vmag Calibrated Johnson V-magnitude band
22- 26 F5.3 mag b-y Stroemgren (b-y) colour index
29- 34 F6.3 mag Jmag ?=99.999 2MASS J-magnitude band
37- 41 F5.3 mag J-Ks ?=9.999 2MASS (J-Ks) colour index
44- 49 F6.3 mag Gmag Gaia-DR2 G-magnitude band
52- 56 F5.3 mag BP-RP Gaia-DR2 (BP-RP) colour index
59- 63 F5.3 mas plx Gaia-DR2 parallax
66- 71 F6.3 mas/yr pmRA* Gaia-DR2 proper motion along RA, pmRA*cosDE
74- 78 F5.3 mas/yr pmDE Gaia-DR2 proper motion along DE
--------------------------------------------------------------------------------
Acknowledgements:
Javier Alonso-Santiago, javier.alonso(at)ua.es
History:
05-Nov-2019: tables A1 and A4
22-Jan-2020: tables A2 and A3 added
(End) Patricia Vannier [CDS] 03-Oct-2019