J/A+A/588/A148 NGC 6397 stars MUSE spectra (Husser+, 2016)
MUSE crowded field 3D spectroscopy of over 12 000 stars in the globular cluster
NGC 6397.
Husser T.-O., Kamann S., Dreizler S., Wendt M., Wulff N., Bacon R.,
Wisotzki L., Brinchmann J., Weilbacher P.M., Roth M.M., Monreal-ibero A.
<Astron. Astrophys., 588, A148 (2016)>
=2016A&A...588A.148H 2016A&A...588A.148H (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Populations, stellar ; Spectroscopy
Keywords: methods: data analysis - techniques: imaging spectroscopy -
planets and satellites: fundamental parameters - stars: atmospheres -
pulsars: general - globular clusters: individual: NGC 6397
Abstract:
We demonstrate the high multiplex advantage of crowded field 3D
spectroscopy with the new integral field spectrograph MUSE by means of
a spectroscopic analysis of more than 12000 individual stars in the
globular cluster NGC 6397.
The stars are deblended with a point spread function fitting
technique, using a photometric reference catalogue from HST as prior,
including relative positions and brightnesses. This catalogue is also
used for a first analysis of the extracted spectra, followed by an
automatic in-depth analysis via a full-spectrum fitting method based
on a large grid of PHOENIX spectra.
We analysed the largest sample so far available for a single globular
cluster of 18 932 spectra from 12 307 stars in NGC 6397. We derived a
mean radial velocity of vrad=17.84±0.07km/s and a mean metallicity
of [Fe/H]=-2.120±0.002, with the latter seemingly varying with
temperature for stars on the red giant branch (RGB). We determine Teff
and [Fe/H] from the spectra, and log g from HST photometry. This is
the first very comprehensive Hertzsprung-Russell diagram (HRD) for a
globular cluster based on the analysis of several thousands of stellar
spectra, ranging from the main sequence to the tip of the RGB.
Furthermore, two interesting objects were identified; one is a
post-AGB star and the other is a possible millisecond-pulsar
companion.
Description:
We observed the globular cluster NGC 6397 during MUSE commissioning,
lasting from July 26nd to August 3rd, 2014, to explore the
capabilities of MUSE in crowded stellar fields.
To obtain clean spectra in a crowded region such as a globular
cluster, sophisticated analysis techniques are required.
Provided are all the obtained spectra with a signal-to-noise ratio of
five or larger, i.e. 14271 spectra in total.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 40 12980 List of stars with spectra
list.dat 150 14271 List of fits spectra
fits/* . 14271 Individual fits spectra
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Byte-by-byte Description of file: sources.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- Star ID of the star in the photometric reference
catalogue
11- 21 F11.7 deg RAdeg Right ascension (J2000) from "HIERARCH STAR
RA" field of the header of spectrum file
23- 33 F11.7 deg DEdeg Declination (J2000) from "HIERARCH STAR DEC"
of the header of spectrum file
35- 40 F6.3 mag mag Magnitude of the star in the photometric filter
provided in "HIERARCH PAMPELMUSE PASSBAND"
from "HIERARCH STAR MAG" field of the header
of spectrum file
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- Star Star identification number (1)
11- 14 I4 --- Nx Number of pixels along X-axis
16- 38 A23 "datime" Obs.dat Observation date
40- 46 F7.2 0.1nm blambda Lower value of wavelength interval
48- 54 F7.2 0.1nm Blambda Upper value of wavelength interval
56- 59 F4.2 01.nm dlambda [1.25] Spectral resolution
61- 62 I2 Kibyte size Size of FITS file
64-104 A41 --- FileName Name of FITS file, in subdirectory fits
106-150 A45 --- Title Title of the FITS file (2)
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Note (1): id is as in the catalogue of Anderson et al. (2008AJ....135.2055A 2008AJ....135.2055A),
for stars included in the ACS catalogue.
For the remaining stars, it is a 9-digit number and the first two digits
indicate the pointing identifier.
Note (2): The title is in the form:
ngc6397 id=NNNNNNNNN JD=DDDDDDD.DDDD Flag=NNN
Flag is a quality flag which is the sum of one or more as follows:
0 = good spectrum
1 = the spectrum includes contributions from more than one star
2 = the spectrum has an estimates S/N<10
4 = the spectrum has a mean flux <0
8 = the centroid of the star is outside the observed field of view
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History:
Copied at http://muse-vlt.eu/science/globular-cluster-ngc-6397/
(End) Patricia Vannier [CDS] 14-Oct-2019