J/ApJ/761/33 Chemical properties of 89 stars in the LMC disk (Lapenna+, 2012)
Tagging the chemical evolution history of the Large Magellanic Cloud disk.
Lapenna E., Mucciarelli A., Origlia L., Ferraro F.R.
<Astrophys. J., 761, 33 (2012)>
=2012ApJ...761...33L 2012ApJ...761...33L
ADC_Keywords: Magellanic Clouds ; Abundances ; Photometry, infrared ;
Radial velocities ; Stars, giant
Keywords: Magellanic Clouds; stars: abundances; techniques: spectroscopic
Abstract:
We have used high-resolution spectra obtained with the multifiber
facility FLAMES at the Very Large Telescope of the European Southern
Observatory to derive kinematic properties and chemical abundances of
Fe, O, Mg, and Si for 89 stars in the disk of the Large Magellanic
Cloud (LMC). The derived metallicity and [α/Fe], obtained as the
average of O, Mg, and Si abundances, allow us to draw a preliminary
scheme of the star formation history of this region of the LMC. The
derived metallicity distribution shows two main components: one
component (comprising ∼84% of the sample) peaks at [Fe/H]=-0.48dex and
it shows an [α/Fe] ratio slightly under solar
([α/Fe]~-0.1dex). This population probably originated in the
main star formation event that occurred 3-4Gyr ago (possibly triggered
by tidal capture of the Small Magellanic Cloud). The other component
(comprising ∼16% of the sample) peaks at [Fe/H]~-0dex and it shows an
[α/Fe]∼0.2dex. This population was probably generated during the
long quiescent epoch of star formation between the first episode and
the most recent bursts. Indeed, in our sample we do not find stars
with chemical properties similar to the old LMC globular clusters nor
to the iron-rich and α-poor stars recently found in the LMC
globular cluster NGC 1718 and also predicted to be in the LMC field,
thus suggesting that both of these components are small (<1%) in the
LMC disk population.
Description:
We have observed 91 stars located in the region surrounding the old GC
NGC 1786 at ∼2° NW from the center of the LMC. The spectra have
been acquired with the multi-object spectrograph FLAMES at the Kueyen
European Southern Observatory Very Large Telescope (ESO-VLT). We
determined kinematic and chemical properties for 89 giant star members
of the disk of the LMC.
The spectroscopic targets have been selected using the near-infrared
(J, H, and K bands) photometric catalog, which was obtained by
combining the SOFI catalog for the inner ∼2.5arcmin, corresponding to
the area covered by GC NGC 1786 (see Mucciarelli et al. 2010
(Cat. J/ApJ/717/277) for details) and the Two Micro All Sky Survey
(2MASS) catalog for the outermost region.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 46 89 Identification number, right ascension, declination
and J, H, K magnitudes
table3.dat 42 89 Identification number, photometric temperature and
gravity, radial velocity, and spectroscopic
atmospheric parameters for stars in our sample
table4.dat 49 89 Derived abundances for the stars in our sample
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
IV/33 : Master Catalogue towards the Magellanic Clouds (MC2) (Delmotte+ 2002)
J/AcA/62/247 : LMC maps from OGLE-III shallow survey (Ulaczyk+, 2012)
J/AJ/144/186 : Variables in LMC globular clusters. II. NGC 1786 (Kuehn+, 2012)
J/ApJ/749/124 : Spectroscopy on LMC clusters (Colucci+, 2012)
J/ApJ/746/29 : High-resolution GC abundances. IV. 8 LMC GCs (Colucci+, 2012)
J/ApJ/735/55 : High-resolution GCs abundances. III. LMC (Colucci+, 2011)
J/ApJ/717/277 : Chemical composition of old LMC clusters (Mucciarelli+, 2010)
J/ApJ/695/L134 : Chemical anomalies in old LMC clusters (Mucciarelli+, 2009)
J/AJ/138/1243 : The star formation history of the LMC (Harris+, 2009)
J/AJ/136/375 : Chemical composition of LMC red giants (Mucciarelli+, 2008)
J/AJ/135/836 : Calcium triplet index in LMC stars (Carrera+, 2008)
J/A+A/480/379 : Abundances of 59 red giants in LMC (Pompeia+, 2008)
J/AJ/132/1630 : CaII spectro. in Magellanic Cloud clusters (Grocholski+, 2006)
J/AJ/129/1465 : Spectroscopy of red giants in the LMC bar (Cole+, 2005)
J/AJ/128/1606 : Magellanic Clouds Phot. Survey: the LMC (Zaritsky+, 2004)
J/MNRAS/339/701 : Velocities and BR photometry in LMC (Zhao+, 2003)
J/A+AS/142/467 : Broadening of metallic lines by H collisions (Barklem+ 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID [353/95454] Identifier
7- 16 F10.7 deg RAdeg [74.2/75.4] Right Ascension (J2000)
18- 28 F11.7 deg DEdeg [-67.95/-67.55] Declination (J2000)
30- 34 F5.2 mag Jmag [12.5/15] 2MASS J band magnitude
36- 40 F5.2 mag Hmag [11.8/14.2] 2MASS H band magnitude
42- 46 F5.2 mag Ksmag [11.7/14] 2MASS Ks band magnitude
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID [353/95454] Identifier
7- 10 I4 K Tphot [3535/4676] Photometric effective temperature
estimate
12- 15 F4.2 [cm/s2] loggp [0.3/1.4] Log of the photometric surface
gravity estimate
17- 21 F5.1 km/s RVel [211.7/327.7] Radial velocity
23- 26 I4 K Tspec [3600/4950] Spectroscopic effective temperature
estimate
28- 31 F4.2 [cm/s2] loggs Log of the spectroscopic surface gravity
estimate
33- 37 F5.2 [Sun] [A/H] [-1.5/0] Overall metallic abundance ratio
39- 42 F4.2 km/s Vt [1.2/2.4] Spectroscopic turbulent velocity ξ
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID [353/95454] Identifier
7- 11 F5.2 [Sun] [Fe/H] [-1.6/-0.09] The Fe/H number abundance
13- 16 F4.2 [Sun] e_[Fe/H] [0.01/0.06] Uncertainty in [Fe/H]
18- 22 F5.2 [Sun] [O/Fe] ? The O/Fe number abundance
24- 27 F4.2 [Sun] e_[O/Fe] ? Uncertainty in [O/Fe]
29- 33 F5.2 [Sun] [Mg/Fe] ? The Mg/Fe number abundance
35- 38 F4.2 [Sun] e_[Mg/Fe] ? Uncertainty in [Mg/Fe]
40- 44 F5.2 [Sun] [Si/Fe] [-0.3/0.5] The Si/Fe number abundance
46- 49 F4.2 [Sun] e_[Si/Fe] [0.01/0.2] Uncertainty in [Si/Fe]
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 05-Aug-2014