J/A+A/634/A51 NGC 330 seen by MUSE (Bodensteiner+, 2020)
The young massive SMC cluster NGC 330 seen by MUSE.
I. Observations and stellar content
Bodensteiner J., Sana H., Mahy L., Patrick L.R., de Koter A., de Mink S.E.,
Evans C.J., Goetberg Y., Langer N., Lennon D.J., Schneider F.R.N.,
Tramper F.
<Astron. Astrophys. 634, A51 (2020)>
=2020A&A...634A..51B 2020A&A...634A..51B (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Clusters, open ; Populations, stellar ;
Equivalent widths
Keywords: stars: massive, emission-line - binaries: spectroscopic -
blue stragglers -
open clusters and associations: individual: NGC 330 -
(Galaxies:) Magellanic Clouds
Abstract:
A majority of massive stars are part of binary systems, a large
fraction of which will inevitably interact during their lives.
Binary-interaction products (BiPs), i.e. stars affected by such
interaction, are expected to be commonly present in stellar
populations. BiPs are thus a crucial ingredient in the understanding
of stellar evolution. We aim to identify and characterize a
statistically significant sample of BiPs by studying clusters of
10-40Myr, an age at which binary population models predict the
abundance of BiPs to be highest. One example of such a cluster is NGC
330 in the Small Magellanic Cloud. Using MUSE WFM-AO observations of
NGC 330, we resolve the dense cluster core for the first time and are
able to extract spectra of its entire massive star population. We
develop an automated spectral classification scheme based on the
equivalent widths of spectral lines in the red part of the spectrum.
We characterize the massive star content of the core of NGC 330 which
contains more than 200 B stars, 2 O stars, 6 A-type supergiants and 11
red supergiants. We find a lower limit on the Be star fraction of
32±3% in the whole sample. It increases to at least 46±10% when
only considering stars brighter than V=17mag. We estimate an age of
the cluster core between 35 and 40Myr and a total cluster mass of
88+17-18*10^3M☉. We find that the population in the cluster
core is different than the population in the outskirts: while the
stellar content in the core appears to be older than the stars in the
outskirts, the Be star fraction and the observed binary fraction are
significantly higher. Furthermore, we detect several BiP candidates
that will be subject of future studies.
Description:
NGC 330 was observed with MUSE in wide-field mode (WFM) with adaptive
optics (AO) on 19 November 2018 at Yepun, one of the four Unit
Telescopes of the VLT in Paranal, Chile. MUSE is an integral-field
spectrograph comprising 24 individual spectrographs. The observations
were carried out in the extended wavelength mode covering a broad
optical range (i.e., 4600Å–9300Å). The spectral resolving power
ranges from 2000 at 4600Å to 4000 at 9300Å. Spectra were
extracted for all stars brighter than 18.5 in V. Their positions are
based on an input list from archival HST data which provides better
spatial resolution and thus more accurate stellar positions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tabled1.dat 97 278 Compilation of all parameters derived for the
sample stars
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See also:
J/A+AS/108/571 : Photometry of the SMC cluster NGC 330 (Vallenari+, 1994)
J/AJ/108/932 : Variable stars in the SMC cluster NGC 330 (Sebo+, 1994)
J/A+A/456/623 : VLT-FLAMES survey of massive stars (Evans+, 2006)
J/A+A/462/683 : Velocities in SMC field of NGC 330 (Martayan+, 2007)
J/A+A/472/577 : NGC 330 Be stars and binaries (Martayan+, 2007)
J/AJ/135/1350 : Hot variable stars in NGC 330 (Schmidtke+, 2008)
Byte-by-byte Description of file: tabled1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Ident [20/739] Identifier from this paper
5- 13 F9.6 deg RAdeg Right ascension (J2000.0)
15- 24 F10.6 deg DEdeg Declination (J2000.0)
26- 29 F4.1 mag Vmag Apparent V-band magnitude
31- 36 F6.3 0.1nm EW5412 ?=- Equivalent width of HeII at 5412Å
38- 42 F5.3 0.1nm e_EW5412 ?=- Equivalent width error of HeII at 5412Å
44- 49 F6.3 0.1nm EW6678 ?=- Equivalent width of HeI at 6678Å
51- 55 F5.3 0.1nm e_EW6678 ?=- Equivalent width error of HeI at 6678Å
57- 62 F6.3 0.1nm EW7774 ?=- Equivalent width of OI at 7774Å
64- 68 D5.3 0.1nm e_EW7774 ?=- Equivalent width error of OI at 7774Å
70- 72 A3 --- Class Classifier (1)
74- 87 A14 --- SpType Spectral type
89- 97 A9 --- Comments Comments, i.e. literature identifiers (2)
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Note (1): Classifier as follows:
B = B-type star
Be = Be star
RSG = Red Supergiant
BSG = Blue Supergiant
err = error with spectral extraction, no uncontaminated spectrum extracted
fg = foreground star
Note (2): in comments,
man_spt = automatic spectral typing was not possible, spectral type was
derived manually
bin = indications for binarity in the spectrum
Arp II-NN = Cl* NGC 330 ARP NN in Simbad
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Acknowledgements:
Julia Bodensteiner, julia.bodensteiner(at)kuleuven.be
(End) Patricia Vannier [CDS] 11-Dec-2019