J/A+A/572/A82 Abundances in outer parts of Fornax dSph (Hendricks+, 2014)
Insights from the outskirts: chemical and dynamical properties in the outer
parts of the Fornax dwarf spheroidal galaxy.
Hendricks B., Koch A., Walker M., Johnson C.I., Penarrubia J., Gilmore G.
<Astron. Astrophys. 572, A82 (2014)>
=2014A&A...572A..82H 2014A&A...572A..82H
ADC_Keywords: Galaxies, nearby ; Abundances ; Equivalent widths
Keywords: galaxies: individual: Fornax - galaxies: abundances -
galaxies: evolution - galaxies: dwarf - galaxies: stellar content -
galaxies: kinematics and dynamics
Abstract:
We present radial velocities and [Fe/H] abundances for 340 stars in
the Fornax dwarf spheroidal from R∼16000 spectra. The targets were
obtained in the outer parts of the galaxy. Our sample shows a wide
range in [Fe/H], between -0.5 and -3.0dex, in which we detect three
subgroups. Removal of stars belonging to the most metal-rich
population produces a truncated metallicity distribution function that
is identical to Sculptor, indicating that these systems shared a
similar early evolution. The derived age-metallicity relation shows a
fast increase in [Fe/H] at early ages, after which the enrichment
flattens significantly for stars younger than ∼8Gyr. Additionally,
the data indicate a strong population of stars around 4Gyr, followed
by a second rapid enrichment in [Fe/H]. Our dynamical analysis reveals
an increasing velocity dispersion with decreasing [Fe/H] from
sigmasys=7.5km/s to 14km/s. The large velocity dispersion at low
metallicities is possibly the result of a non-Gaussian velocity
distribution among stars older than ∼8Gyr. Our sample also includes
members from the Fornax globular clusters H2 and H5. In agreement with
past studies we find [Fe/H]=-2.04±0.04 and a mean radial velocity
RV=59.36±0.31km/s for H2 and [Fe/H]=-2.02±0.11 and
RV=59.39±0.44km/s for H5. Overall, we find high complexity in the
chemical and dynamical properties, with signatures that additionally
vary with galactocentric distance.
Description:
The spectra for this study have been obtained in November 2008 with
FLAMES at the VLT (programme ID 082.B-0940(A)) , where we used GIRAFFE
in MEDUSA high-resolution mode (HR21, R∼16000, 8484-9001Å).
Tables A1-A3 are presented here in combined tables.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 238 340 Chemodynamical properties of field stars
table2.dat 238 13 Chemodynamical properties of stars in the
globular clusters H2 and H5 (1961AJ.....66...83H 1961AJ.....66...83H)
--------------------------------------------------------------------------------
See also:
J/AJ/131/912 : BR photometry of Fornax dSph center (Olszewski+, 2006)
J/AJ/131/2114 : Radial velocities in Fornax dSph (Walker+, 2006)
J/ApJ/701/1323 : Variable stars in Fornax dSph. III. (Greco+, 2009)
J/A+A/523/A17 : Individual stars in Fornax dSph center (Letarte+, 2010)
J/A+A/544/A73 : BVI photometry of Fornax dSph galaxy (de Boer+, 2012)
J/A+A/550/A18 : XMM X-ray sources in Fornax dwarf galaxy (Nucita+, 2013)
J/A+A/562/A24 : Cool carbon stars in the halo and Fornax dSph (Mauron+, 2014)
Byte-by-byte Description of file: table[12].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Star [1/431] Star sequential number
7- 8 I2 h RAh Right ascension (J2000)
12- 13 I2 min RAm Right ascension (J2000)
17- 21 F5.2 s RAs Right ascension (J2000)
25 A1 --- DE- Declination sign (J2000)
29- 30 I2 deg DEd Declination (J2000)
34- 35 I2 arcmin DEm Declination (J2000)
39- 43 F5.2 arcsec DEs Declination (J2000)
47- 50 F4.1 --- S/N [10/53] Signal-to-noise per pixel
54- 58 F5.2 km/s RV [26/87] Radial velocity
62- 65 F4.2 km/s e_RV [0.5/3.6] Error on RV
69- 74 F6.3 mag Vmag [18/21] V magnitude
78- 82 F5.3 mag e_Vmag [0/0.2] Error on Vmag
86- 90 F5.3 mag V-I V-I color index
94- 98 F5.3 mag e_V-I Error on V-I
102-106 F5.2 [Sun] [Fe/H]Ca [-3/-0.4] Metallicity derived from
Calcium Triplet (CaT)
110-115 F6.3 [Sun] e_[Fe/H]Ca Error on [Fe/H]Ca
119-124 F6.3 Gyr Age ?=99.999 Stellar age
128-133 F6.3 0.1nm EWCaT1 Equivalent width of CaT1 line (849.8nm)
137-141 F5.3 0.1nm EWCaT2 Equivalent width of CaT2 line (854.2nm)
145-149 F5.3 0.1nm EWCaT3 Equivalent width of CaT3 line (866.2nm)
153-157 F5.3 0.1nm EWMg ?=9.999 Equivalent width of Mg line at 880.7nm
161-166 F6.3 [Sun] [Fe/H]HR [-6.9/0.5]?=99.999 Metallicity derived from
Fe absorption features
170-175 F6.3 [Sun] e_[Fe/H]HR ?=99.999 Error on [Fe/H]HR
179-184 F6.3 [Sun] [Mg/Fe] ?=99.999 Derived [Mg/Fe] abundance
188-193 F6.3 [Sun] e_[Mg/Fe] ?=99.999 Error on [Mg/Fe]
197-202 F6.3 [Sun] [Si/Fe] ?=99.999 Derived [Si/Fe] abundance
206-211 F6.3 [Sun] e_[Si/Fe] ?=99.999 Error on [Si/Fe]
215-220 F6.3 [Sun] [Ti/Fe] ?=99.999 Derived [Ti/Fe] abundance
224-229 F6.3 [Sun] e_[Ti/Fe] ?=99.999 Error on [Ti/Fe] abundance
233-238 F6.3 --- chi2 [0/5]?=99.999 Normalized χ2 fit (1)
--------------------------------------------------------------------------------
Note (1): Normalized χ2 of the spectral for individual abundances
with SPACE (Boeche et al. 2013, in IAU Symposium 298 "Setting the scene
for Gaia and LAMOST", 1309.6460
--------------------------------------------------------------------------------
Acknowledgements:
Benjamin Hendricks, ben.hendricks(at)lsw.uni-heidelberg.de
(End) Benjamin Hendricks [LSW, Heidelberg], Patricia Vannier [CDS] 02-Oct-2014