J/A+A/676/A140 Stars from GAIA and APOGEE data (Ortigoza-Urdaneta+, 2023)
Galactic ArchaeoLogIcaL ExcavatiOns (GALILEO).
II. t-SNE portrait of local fossil relics and structures.
Ortigoza-Urdaneta M., Vieira K., Fernandez-Trincado J.G., Queiroz A..B.A.,
Barbuy B., Beers T.C., Chiappini C., Anders F., Minniti D., Tang B.
<Astron. Astrophys. 676, A140 (2023)>
=2023A&A...676A.140O 2023A&A...676A.140O (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Stars, giant ; Abundances ; Optical ; Infrared
Keywords: stars: abundances - stars: chemically peculiar - solar neighborhood -
Galaxy: halo - techniques: spectroscopic - methods: statistical
Abstract:
Based on high-quality APOGEE DR17 and Gaia DR3 data for 1742 red
giants stars within 5 kpc of the Sun and not rotating with the
Galactic disc (Vphi<100km/s), we use the nonlinear technique of
unsupervised analysis t-SNE to detect coherent structures in the space
of ten chemical-abundance ratios: [Fe/H], [O/Fe], [Mg/Fe], [Si/Fe],
[Ca/Fe], [C/Fe], [N/Fe], [Al/Fe], [Mn/Fe], and [Ni/Fe]. Additionally,
we obtain orbital parameters for each star using the non-axisymmetric
gravitational potential GravPot16. Seven structures are detected,
including the Splash, Gaia-Sausage-Enceladus (GSE), the high-alpha
heated-disc population, N-C-O peculiar stars, and inner disk-like
stars, plus two other groups that did not match anything previously
reported in the literature, here named Galileo 5 and Galileo 6 (G5 and
G6). These two groups overlap with Splash in [Fe/H], G5 being lower
metallicity than G6, both between GSE and Splash in the [Mg/Mn] versus
[Al/Fe] plane, G5 in the alpha -rich in-situ locus, and G6 on the
border of the alpha-poor in-situ one; nonetheless their low [Ni/Fe]
hints to a possible ex-situ origin. Their orbital energy distributions
are between the Splash and GSE, with G5 being slightly more energetic
than G6. We verified the robustness of all the obtained groups by
exploring a large range of t-SNE parameters, applying it to various
subsets of data, and also measuring the effect of abundance errors
through Monte Carlo tests.
Description:
We have used high-quality APOGEE abundances and Gaia astrometric data
for 1742 red giant stars located within 5kpc of the Sun, in order to
detect coherent structures associated in the
chemical-kinematic-dynamical space. We limited our study to stars not
rotating with the disc, i.e, Vphi<100km/s.
We determined orbital parameters using the nonaxisymmetric galactic
potential model GravPot16, which, together with the stellar components
for the disc and halo of the MW, also includes a rotating bar it
boxy/peanut. The bar pattern velocity adopted was 41km/s/kpc.
They were also determined for velocities 31 and 51km/s/kpc in
order to measure the impact on the orbital parameters, since these
stars may spend a significant portion of their orbits close to the
Galactic plane. We did not detect significant variations in this
regard.
The search for structures was performed with the nonlinear algorithm
of dimensional reduction known as t-SNE, using ten chemical-abundance
ratios as input data: [Fe/H], [O/Fe], [Mg/Fe], [Si/Fe], [Ca/Fe],
[C/Fe], [N/Fe], [Al/Fe], [Mn/Fe], and [Ni/Fe].
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablec1.dat 497 1742 Relevant information for each star used in this
investigation, including a tag for each
detected group
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)
J/A+A/673/A155 : StarHorse data for 8 spectroscopic surveys (Queiroz+, 2023)
J/A+A/663/A126 : GALILEO. I. New N rich stars (Fernandez-Trincado+, 2022)
Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- APOGEE APOGEE id (2MHHMMSSss+DDMMSSs)
20- 29 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
31- 40 F10.6 deg DEdeg Declination in decimal degrees (J2000)
42- 51 F10.5 pix-1 SNR Spectral signal-to-noise
53- 59 F7.2 km/s RV APOGEE-2 radial velocity
61- 71 F11.6 km/s Vscatter APOGEE-2 radial velocity scatter
73- 78 F6.4 [cm/s2] logg Surface gravity
80- 85 F6.4 [cm/s2] e_logg Uncertainty in logg
87- 95 F9.5 --- [C/Fe] Abundance [C/Fe] from ASPCAP
97-103 F7.5 --- e_[C/Fe] Uncertainty in [C/Fe]
105-113 F9.5 --- [N/Fe] Abundance [N/Fe] from ASPCAP
115-121 F7.5 --- e_[N/Fe] Uncertainty in [N/Fe]
123-131 F9.5 --- [O/Fe] Abundance [O/Fe] from ASPCAP
133-139 F7.5 --- e_[O/Fe] Uncertainty in [O/Fe]
141-149 F9.5 --- [Mg/Fe] Abundance [Mg/Fe] from ASPCAP
151-157 F7.5 --- e_[Mg/Fe] Uncertainty in [Mg/Fe]
159-167 F9.5 --- [Al/Fe] Abundance [Al/Fe] from ASPCAP
169-175 F7.5 --- e_[Al/Fe] Uncertainty in [Al/Fe]
177-184 F8.5 --- [Si/Fe] Abundance [Si/Fe] from ASPCAP
186-192 F7.5 --- e_[Si/Fe] Uncertainty in [Si/Fe]
194-202 F9.5 --- [Ca/Fe] Abundance [Ca/Fe] from ASPCAP
204-210 F7.5 --- e_[Ca/Fe] Uncertainty in [Ca/Fe]
212-219 F8.5 --- [Mn/Fe] Abundance [Mn/Fe] from ASPCAP
221-227 F7.5 --- e_[Mn/Fe] Uncertainty in [Mn/Fe]
229-236 F8.5 --- [Fe/H] Abundance [Fe/H] from ASPCAP
238-244 F7.5 --- e_[Fe/H] Uncertainty in [Fe/H]
246-254 F9.5 --- [Ni/Fe] Abundance [Ni/Fe] from ASPCAP
256-262 F7.5 --- e_[Ni/Fe] Uncertainty in [Ni/Fe]
264-273 F10.5 km/s VR Galactocentric radial velocity
275-284 F10.5 km/s Vphi Galactocentric azimuthal velocity
286-292 F7.5 kpc Rperi Perigalactocentric distance
294-300 F7.5 kpc e_Rperi Uncertainty in PERIGALACTICON
302-309 F8.5 kpc Rapo Apogalactocentric distance
311-318 F8.5 kpc e_Rapo Uncertainty in APOGALACTICON
320-326 F7.5 --- Ecc Orbital eccentricity
328-335 F8.5 --- e_Ecc Uncertainty in eccentricity
337-344 F8.5 kpc Zmax Maximum vertical excursion from
the Galactic plane
346-353 F8.5 kpc e_Zmax Uncertainty in Zmax
355-365 F11.5 10+2km2/s2 Ej Jacobi energy
367-375 F9.5 10+2km2/s2 e_Ej Uncertainty in Jacobi energy
377-387 F11.5 10+2km2/s2 Echar Characteristic orbital energy
389-397 F9.5 10+2km2/s2 e_Echar Uncertainty in Characteristic
orbital energy
399-404 F6.1 10+2km2/s2 Lmin Minimum z-component of angular momentum
406-410 F5.2 10+2km2/s2 e_Lmin Uncertainty in minimum z-component of
angular momentum
412-417 F6.1 10+2km2/s2 Lmax Maximum z-component of angular momentum
419-423 F5.2 10+2km2/s2 e_Lmax Uncertainty in maximum z-component of
angular momentum
425-443 I19 --- GaiaDR3 GAIA DR3 source id
445-449 F5.3 --- RUWE Gaia DR3 renormalized unit weight error
451-457 F7.5 kpc Dist Bayesian StarHorse distance,
50th percentile
459-466 F8.5 kpc e_Dist Uncertainty in Dist,
error=(84th-16th)/2 percentile
468-475 F8.3 mas/yr pmRA Proper motion along RA, pmRAcos(DE),
from Gaia DR3
477-481 F5.3 mas/yr e_pmRA Uncertainty in pmRAcos(DE) from Gaia DR3
483-489 F7.3 mas/yr pmDE Proper motion along DE from Gaia DR3
491-495 F5.3 mas/yr e_pmDE Uncertainty in pmDE from Gaia DR3
497 I1 --- Group [1/7] Group as determined by t-SNE
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Acknowledgements:
Mario Ortigoza, marioortigoza81(at)gmail.com
(End) Patricia Vannier [CDS] 05-Jul-2023