J/A+A/618/A102 GES N/O abundance ratio in the Milky Way (Magrini+, 2018)
The Gaia-ESO Survey: The N/O abundance ratio in the Milky Way.
Magrini L., Vincenzo F., Randich S., Pancino E., Casali G., Tautvaisiene G.,
Drazdauskas A., Mikolaitis S., Minkeviciute R., Stonkute E., Chorniy Y.,
Bagdonas V., Kordopatis G., Friel E., Roccatagliata V.,
Jimenez-Esteban F.M., Gilmore G., Vallenari A., Bensby T., Bragaglia A.,
Korn A.J., Lanzafame A.C., Smiljanic R., Bayo A., Casey A.R., Costado M.T.,
Franciosini E., Hourihane A., Jofre , Lewis J., Monaco L., Morbidelli L.,
Sacco G., Worley C.
<Astron. Astrophys. 618, A102 (2018)>
=2018A&A...618A.102M 2018A&A...618A.102M (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, open ; Abundances
Keywords: Galaxy: abundances - open clusters and associations: general -
Galaxy: disk
Abstract:
The abundance ratio N/O is a useful tool to study the interplay of
galactic processes, for example star formation efficiency, timescale
of infall, and outflow loading factor.
We aim to trace log(N/O) versus [Fe/H] in the Milky Way and to compare
this ratio with a set of chemical evolution models to understand the
role of infall, outflow, and star formation efficiency in the building
up of the Galactic disc.
We used the abundances from idr2-3, idr4, idr5 data releases of the
Gaia-ESO Survey both for Galactic field and open cluster stars. We
determined membership and average composition of open clusters and we
separated thin and thick disc field stars. We considered the effect of
mixing in the abundance of N in giant stars. We computed a grid of
chemical evolution models, suited to reproduce the main features of
our Galaxy, exploring the effects of the star formation efficiency,
infall timescale, and differential outflow.
With our samples, we map the metallicity range -0.6≤[Fe/H]≤0.3 with
a corresponding -1.2≤log(N/O)≤-0.2, where the secondary production
of N dominates. Thanks to the wide range of Galactocentric distances
covered by our samples, we can distinguish the behaviour of log(N/O)
in different parts of the Galaxy.
Our spatially resolved results allow us to distinguish differences in
the evolution of N/O with Galactocentric radius. Comparing the data
with our models, we can characterise the radial regions of our Galaxy.
A shorter infall timescale is needed in the inner regions, while the
outer regions need a longer infall timescale, coupled with a higher
star formation efficiency. We compare our results with nebular
abundances obtained in MaNGA galaxies, finding in our Galaxy a much
wider range of log(N/O) than in integrated observations of external
galaxies of similar stellar mass, but similar to the ranges found in
studies of individual HII regions.
Description:
Our samples are composed by Milky Way field stars and stars in open
clusters. The former sample includes stars observed with the UVES
set-up centred around 580.0nm, which belong to the solar
neighbourhood and inner disc samples. We divided the field stars into
thin and thick disc stars, using their [alpha/Fe] abundance ratio,
following the approach of Adibekyan et al. (2011A&A...535L..11A 2011A&A...535L..11A). Our
sample includes 19 thin disc stars and 130 thick disc stars with both
N and O measurements. Their stellar parameters and the abundances of N
and O are listed in tablea1.dat.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 77 17 Open cluster parameters and abundances
tablea1.dat 82 149 Thin and thick disc star parameters and abundances
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See also:
J/A+A/566/A50 : Classification of stellar spectra 644-681nm (Damiani+, 2014)
J/A+A/572/A33 : Abundances from Gaia-ESO Survey (Mikolaitis+, 2014)
J/A+A/589/A115 : Na and Al abundances of 1303 stars (Smiljanic+, 2016)
J/A+A/603/A2 : GES abundances radial distribution (Magrini+, 2017)
J/A+A/604/A128 : S abundances for 1301 stars from GES (Duffau+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Cluster Cluster name
13- 16 F4.2 Gyr Age Age
18- 21 F4.2 Gyr e_Age rms uncertainty on Age
23- 26 F4.2 Msun MTO Turn-off mass (1)
28- 32 F5.2 kpc RGC Galactoccentric radius
34- 37 F4.2 kpc e_RGC rms uncertainty on RGC
39- 43 F5.2 [-] [Fe/H] Metallicity
45- 48 F4.2 [-] e_[Fe/H] rms uncertainty on [Fe/H]
50- 53 F4.2 --- 12+log(O/H) Abundance 12+log(O/H)
55- 58 F4.2 --- e_12+log(O/H) rms uncertainty on 12+log(O/H)
60- 63 F4.2 --- 12+log(N/H) Abundance 12+log(N/H)
65- 68 F4.2 --- e_12+log(N/H) rms uncertainty on 12+log(N/H)
70- 71 I2 --- Nstar Number of stars
73- 77 A5 --- DR Data release number(s)
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Note (1): derived from Parsec isochrones using ages and [Fe/H] in the table.
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Disc [Thin Thick] thin or thick disc stars
7- 22 A16 --- CName CNAME (HHMMSSss+DDMMSSs)
24- 27 I4 K Teff Effective temperature
29- 30 I2 K e_Teff rms uncertainty on effective temperature
32- 35 F4.2 [cm/s2] logg Surface gravity
37- 40 F4.2 [cm/s2] e_logg rms uncertainty on surface gravity
42- 45 F4.2 km/s ksi Microturbulent velocity
47- 50 F4.2 km/s e_ksi rms uncertainty on microturbulent velocity
52- 56 F5.2 [-] [Fe/H] Metallicity
58- 61 F4.2 [-] e_[Fe/H] rms uncertainty on metallicity
63- 67 F5.2 --- 12+log(O/H) Abundance 12+log(O/H)
69- 72 F4.2 --- e_12+log(O/H) rms uncertainty on abundance 12+log(O/H)
74- 77 F4.2 --- 12+log(N/H) Abundance 12+log(N/H)
79- 82 F4.2 --- e_12+log(N/H) rms uncertainty on abundance 12+log(N/H)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 15-Oct-2018