J/A+A/684/A91 High-speed stars. II. (Bonifacio+, 2024)
High-speed stars. II:
An unbound star, young stars, bulge metal-poor stars, and Aurora candidates.
Bonifacio P., Caffau E., Monaco L., Sbordone L., Spite M., Mucciarelli A.,
Francois P., Lombardo L., Matas Pinto A.d.M.
<Astron. Astrophys. 684, A91 (2024)>
=2024A&A...684A..91B 2024A&A...684A..91B (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, high-velocity ; Abundances ; Space velocities
Keywords: stars: abundances - Galaxy: abundances - Galaxy: formation -
Galaxy: halo - Galaxy: kinematics and dynamics
Abstract:
The data from the Gaia satellite led us to revise our conception of
the Galaxy structure and history. Hitherto unknown components have
been discovered and a deep re-thinking of what the Galactic halo is is
in progress.
We selected from the Gaia catalogue stars with extreme transverse
velocities with respect to the Sun (|VT|>500km/s) and observed them
with FORS2 at the ESO VLT, to classify them using both their chemical
and dynamical properties. Two apparently young stars, identified in
paper I (Caffau et al., 2020A&A...638A.122C 2020A&A...638A.122C, Cat. J/A+A/638/A122),
were observed with UVES.
We derived abundances for Na, Mg, Ca, Ti, Mn, and Fe, analysing the
spectra with MyGIsFOS, while for Ba we used line profile fitting. We
computed actions from parallaxes and kinematical data.
The stars span the metallicity range -3.5≤[Fe/H]≤-0.5 with
<[Fe/H]≥-1.6. Star GHS143 has a total speed of about 1440km/s,
which is almost three times faster than the local escape velocity of
522km/s, strongly implying this star is unbound to the Galaxy.
Remarkably, this star is not escaping from the Galaxy, but it is
falling into it. Ten stars are apparently young with masses in excess
of 1.3M☉. Their interpretation as evolved blue stragglers is
doubtful. The existence of a young metal-poor population is possible.
The two stars observed with UVES show no lithium, suggesting they are
blue stragglers. We detected a metal-poor population, confined to the
bulge, that we call SpiteF, and argue that it is the result of a
recent accretion event. We detect 102 candidates of the Aurora
population that should have formed prior to the formation of the disc.
Our sample is non-homogeneous and mainly retrograde. The stars are
metal poor, and 23% have [Fe/H]≤-2.0. Our selection is efficient at
finding very metal-poor stars, but it selects peculiar populations.
Description:
In ESO periods 105 and 106, we observed 287 FORS spectra of 278 stars.
We used GRISM 600B+22 and a 0.28 arcsec slit.
In this data file we provide atmospheric parameters, derived from Gaia
photometry and parallaxes, as well as the orbital parameters for all
the stars, as well as for the stars analysed in Paper I (Caffau et al.,
2020A&A...638A.122C 2020A&A...638A.122C, Cat. J/A+A/638/A122).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 1036 348 Full chemical and kinematical data
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See also:
J/A+A/638/A122 : High-speed stars. Galactic hitchhikers (Caffau+, 2020)
J/A+A/684/L4 : High speed stars. III. Line list (Caffau+, 2024)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Name Short name
8- 10 I3 --- Num Running Number of the program star
12- 30 I19 --- GaiaDR3 Gaia DR3 ID
32- 35 I4 K Teff Effective temperature
37- 40 F4.2 [cm/s2] logg logarithm of surface gravity
42- 44 F3.1 km/s micro Microturbulent velocity
46- 51 F6.3 --- [Fe/H] Abundance
[Fe/H]=log10(Fe/H)-log10(Fe/H)Sun
53- 57 F5.3 --- Fe1 log10(FeI/H)+12
59- 62 F4.2 --- sigmaFe1 Line-to-line scatter on FeI
64- 65 I2 --- NFe1 Number of FeI lines used
67- 70 F4.2 --- Na1 ?=- log10(Na/H)+12
72- 79 F8.6 --- sigmaNa1 ?=- Error on Na abundance
81 I1 --- NNa1 ?=- Number of NaI lines
83- 91 F9.6 --- Na1Fe ?=- Abundance [Na/Fe]
93- 96 F4.2 --- Mg1 ?=- log10(Mg/H)+12.
98- 105 F8.6 --- sigmaMg1 ?=- Error on Mg abundance
107 I1 --- NMg1 ?=- Number of MgI lines
109- 112 F4.2 --- Mg1Fe ?=- Abundance [Mg/Fe]
114- 117 F4.2 --- Ca1 ?=- log10(CaI/H)+12
119- 122 F4.2 --- sigmaCa1 ?=- Error on Ca abundance
124 I1 --- NCa1 ?=- Number of CaI lines
126- 131 F6.3 --- Ca1Fe ?=- Abundance [Ca/Fe]
133- 136 F4.2 --- Ti1 ?=- log10(TiI/Fe)+12
138- 145 F8.6 --- sigmaTi1 ?=- Error on TiI abundance
147 I1 --- NTi1 ?=- Number of TiI lines
149- 153 F5.2 --- Ti1Fe ?=- Abundance [TiI/Fe]
155- 158 F4.2 --- Ti2 ?=- log10(TiII/H)+12
160- 163 F4.2 --- sigmaTi2 ?=- Error on TiII abundance
165 I1 --- NTi2 ?=- Number of TiII lines
167- 171 F5.2 --- Ti2Fe ?=- Abundance [TiII/Fe]
173- 180 F8.6 --- sigmaMn1 ?=- Error on Mn abundance
182 I1 --- NMn1 ?=- Number of Mn lines
184- 192 F9.6 --- Mn1Fe ?=- Abundance [Mn/Fe]
198 A1 --- l_Ba2 Upper limit flag on Ba
200- 205 F6.3 --- Ba2 ?=- log10(BaII/H)+12
207- 212 F6.3 --- Ba2Fe ?=- Abundance [Ba/Fe]
214- 222 F9.6 --- cnlte ?=- NLTE correction on Ba
224- 229 F6.3 --- Ba2nlte ?=- log10(BaII/H)+12+cnlte
231- 237 F7.3 --- Ba2Fenlte ?=- Abundance [BaII/Fe] corrected
for NLTE
239- 245 F7.4 mag Gmag0 Gaia G magnitude corrected for reddening
247- 253 F7.4 mag GMAG0 Gaia G absolute magnitude
255- 262 F8.6 mag BP-RP0 Gaia (BP-RP) colour corrected for
reddening
264- 271 A8 --- Paper Paper in which the abundances were
published
273- 285 A13 --- Component Galactic component to which the star
belongs
287- 291 A5 --- Young For young stars this string=YOUNG,
for the others NULL
293- 298 A6 --- SpiteF For stars that belong to SpiteF the
string=SpiteF for the others NULL
300- 307 A8 --- Accreted ACCRETED, IN SITU or NULL
309- 314 A6 --- AURORA AURORA for the AURORA candidates NULL
otherwise
316- 325 F10.6 deg RAdeg Right Ascension (J2000)
327- 336 F10.6 deg DEdeg Declination (J2000)
338- 346 F9.7 mas plx Adopted parallax
348- 355 F8.4 mas pmRA Proper motion in right ascension
357- 364 F8.4 mas pmDE Proper motion in declination
366- 371 F6.1 km/s RV Radial velocity
373- 380 F8.5 kpc dist Distance
382- 389 F8.5 kpc r Galactocentric distance
391- 399 F9.6 kpc R Cylindrical Galactocentric distance
401- 409 F9.4 km/s vR Velocity in the R direction
411- 419 F9.4 km/s vT Transverse velocity in cylindrical
Galactocentric coordinates
421- 428 F8.5 kpc z Vertical cylindrical Galactocentric
coordinate
430- 437 F8.3 km/s vz Velocity along Z
439- 446 F8.5 kpc x X Galactocentric cartesian coordinate
448- 455 F8.3 km/s vx Velocity along X
457- 464 F8.5 kpc y Y Galactocentric cartesian coordinate
466- 474 F9.3 km/s vy Velocity along Y
476- 484 F9.6 rad phi Azimuthal cylindrical coordinate
486- 494 F9.3 km/s vphi Velocity in the phi direction
496- 503 F8.3 km/s U Heliocentric velocity in the R direction
505- 513 F9.3 km/s V Heliocentric velocity in the direction of
Galactic rotation
515- 522 F8.3 km/s W Heliocentric velocity in the vertical
direction
524- 532 F9.5 kpc rap ?=- Distance of orbit apocentre
534- 541 F8.6 kpc rperi ?=- Distance of orbit pericentre
543- 551 F9.7 --- e ?=- Orbit eccentricity adimensional
553- 562 F10.6 kpc zmax ?=- Maximum height from the Galactic
plane
564- 573 F10.2 km2/s2 E ?=- Specific energy
575- 582 F8.2 kpc.km/s Lx ?=- Angular momentum in the X direction
584- 591 F8.2 kpc.km/s Ly ?=- Angular momentum in the Y direction
593- 600 F8.2 kpc.km/s Lz ?=- Angular momentum in the Y direction
602- 612 F11.5 kpc.km/s Jr ?=- Radial action kpc km
614- 624 F11.5 kpc.km/s Jp ?=- Azimuthal action (≡Lz)
626- 635 F10.5 kpc.km/s Jz ?=- Vertical action
637- 646 F10.5 km/s vtotal Total speed
648- 656 F9.5 km/s vescape Escape velocity at the current
position of the star
658- 665 F8.6 mas e_RAdeg Error on right ascension
667- 674 F8.6 mas e_DEdeg Error on declination
676- 685 F10.8 mas e_plx Error on parallax
687- 696 F10.8 mas e_pmRA Error on proper motion in right ascension
698- 707 F10.8 mas e_pmDE Error on proper motion in declination
709- 712 F4.1 km/s e_RV Error on radial velocity
714- 722 F9.7 kpc e_dist Error on distance
724- 733 F10.8 kpc e_r Error on Galactocentric distance
735- 744 F10.8 kpc e_R Error on cylindrical Galactocentric
distance
746- 756 F11.7 km/s e_vR Error on velocity in R direction
758- 768 F11.7 km/s e_vT Error on cylindrical Galactocentric
velocity
770- 778 F9.7 kpc e_z Error on Z
780- 788 F9.6 km/s e_vz Error on Vz
790- 799 F10.8 kpc e_x Error on X
801- 810 F10.6 km/s e_vx Error on Vx
812- 821 F10.8 kpc e_y Error on Y
823- 832 F10.6 km/s e_vy Error on Vy
834- 843 F10.8 rad e_phi Error on phi
845- 854 F10.5 km/s e_vphi Error on Vphi
856- 865 F10.6 km/s e_U Error on U
867- 875 F9.5 km/s e_V Error on V km/s
877- 885 F9.6 km/s e_W Error on W km/s
887- 896 F10.7 kpc e_rap ?=- Error on apocentre distance
898- 906 F9.7 kpc e_rperi ?=- Error on pericentre distance
908- 918 F11.9 --- e_e ?=- Error on eccentricity
920- 929 F10.7 kpc e_zmax ?=- Error on Zmax
931- 939 F9.3 km2/s2 e_E ?=- Error on specific energy
941- 949 F9.5 kpc.km/s e_Lx ?=- Error on angular momentum in
X direction
951- 958 F8.4 kpc.km/s e_Ly ?=- Error on angular momentum in
Y direction
960- 968 F9.5 kpc.km/s e_Lz ?=- Error on angular momentum in
Z direction
970- 979 F10.5 kpc.km/s e_Jr ?=- Error on radial action
981- 989 F9.5 kpc.km/s e_Jp ?=- Error on azimuthal action
991- 999 F9.5 kpc.km/s e_Jz ?=- Error on vertical action
1001-1011 F11.7 deg GLON Galactic longitude
1013-1023 F11.7 deg GLAT Galactic latitude
1025-1036 F12.7 deg GLON1 [] l if l≤180°; l-360 if l>180°
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Acknowledgements:
Piercarlo Bonifacio, Piercarlo.Bonifacio(at)obspm.fr
References:
Caffau et al., Paper I 2020A&A...638A.122C 2020A&A...638A.122C, Cat. J/A+A/638/A122
Caffau et al., Paper III 2024A&A...684L...4C 2024A&A...684L...4C, Cat. J/A+A/684/L4
(End) Patricia Vannier [CDS] 19-Jan-2024