J/A+A/565/A49 Integrated spectroscopy of 6 LMC clusters (Minniti+, 2014)
Reddening and age of six poorly studied star clusters of the Large Magellanic
Cloud derived from integrated spectra.
Minniti J.H., Ahumada A.V., Claria J.J., Benitez-Llambay A.
<Astron. Astrophys. 565, A49 (2014)>
=2014A&A...565A..49M 2014A&A...565A..49M
ADC_Keywords: Magellanic Clouds ; Associations, stellar ; Radial velocities
Keywords: techniques: spectroscopic - Magellanic Clouds -
galaxies: star clusters: general
Abstract:
To increase the number of studied star clusters (SCs) of the Large
Magellanic Cloud (LMC), we present flux-calibrated integrated spectra
in the optical range (λ=3700-6800Å) for six poorly
studied LMC SCs of IVA type. This type corresponds to the age range
between 200 and 400Myr. We also aim at creating a new template
spectrum representative of this age range at the metallicity level of
the LMC.
Foreground reddening E(B-V) values and ages are derived by applying
the template matching method that consists of comparing the line
strengths and continuum distribution of the cluster spectra with those
of template cluster spectra with known properties. The equivalent
width (EW) of the Balmer lines and the diagnostic diagrams involving
the sum of EWs of selected spectral lines were also employed as age
indicators.
For the first time we provide estimates of the clusters' reddenings
and ages. As expected, all the clusters appear to be of nearly the
same age, their mean value being (400±100)Myr, while the
resulting mean E(B-V) values range between 0.00 and 0.10mag.
The present cluster sample complements previous ones in an effort to
gather a spectral library with several clusters per age bin. By
averaging the reddening-corrected integrated spectra, weighted by
their signal-to-noise (S/N) ratios, a new high S/N ratio template
spectrum of 400Myr has been created.
Description:
The observations were carried out with the Jorge Sahade 2.15m
telescope at Complejo Astronomico El Leoncito (CASLEO, San Juan
Argentina) during eight nights in December 2009 and 2012. We employed
the REOSC spectrograph (simple mode). The slit was set in the
East-West direction, and the observations were performed by scanning
the slit across the objects in the North-South direction. We used a
grating of 300 grooves/mm, which produces an average dispersion in the
observed region of ∼140Å/mm (3.46Å/pix). The useful spectral
coverage was λ=3700-6800Å. Here we present the integrated
spectra for the six SCs, corrected by radial velocity, and the new
created template.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
spectra.dat 98 7 List of spectra
sp/* . 7 Individual spectra as FITS files
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Byte-by-byte Description of file: spectra.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Cluster Name of star cluster (1)
9- 10 I2 h RAh ? Right ascension (J2000)
12- 13 I2 min RAm ? Right ascension (J2000)
15- 16 I2 s RAs ? Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd ? Declination (J2000)
22- 23 I2 arcmin DEm ? Declination (J2000)
25- 26 I2 arcsec DEs ? Declination (J2000)
28- 34 F7.2 nm lam.0 Lower value of wavelength interval
36- 42 F7.2 nm lam.1 Upper value of wavelength interval
44- 50 F7.5 nm dlam Wavelength resolution
52- 55 I4 --- Nx Number of points in spectrum
57- 58 I2 Kibyte size Size of FITS file
60- 80 A21 --- FileName Name of the file containing the spectrum in
subdirectory sp (1)
82- 98 A17 --- Title Title of the file
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Note (1): Ygh refers to the template name.
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Acknowledgements:
Javier H. Minniti, javiminniti(at)gmail.com
(End) Patricia Vannier [CDS] 24-Mar-2014