J/MNRAS/497/L7 Galactic disc Pristine low-metallicity stars (Sestito+, 2020)
The Pristine survey.
X. A large population of low-metallicity stars permeates the Galactic disc.
Sestito F., Martin N.F., Starkenburg E., Arentsen A., Ibata R.A.,
Longeard N., Kielty C., Youakim K., Venn K.A., Aguado D.S., Carlberg R.G.,
Gonzalez Hernandez J.I., Hill V., Jablonka P., Kordopatis G., Malhan K.,
Navarro J.F., Sanchez-Janssen R., Thomas G., Tolstoy E., Wilson T.G.,
Palicio P.A., Bialek S., Garcia-Dias R., Lucchesi R., North P., Osorio Y.,
Patrick L.R., Peralta de Arriba L.
<Mon. Not. R. Astron. Soc., 497, L7-12 (2020)>
=2020MNRAS.497L...7S 2020MNRAS.497L...7S (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, metal-deficient ; Stars, distances ; Optical
Keywords: Galaxy: abundances - Galaxy: disc - Galaxy: evolution -
Galaxy: formation - Galaxy: halo - Galaxy: kinematics and dynamics
Abstract:
The orbits of the least chemically enriched stars open a window on the
formation of our Galaxy when it was still in its infancy. The common
picture is that these low-metallicity stars are distributed as an
isotropic, pressure-supported component since these stars were either
accreted from the early building blocks of the assembling Milky Way
(MW), or were later brought by the accretion of faint dwarf galaxies.
Combining the metallicities and radial velocities from the Pristine
and LAMOST surveys and Gaia DR2 parallaxes and proper motions for an
unprecedented large and unbiased sample of 1027 very metal poor stars
at [Fe/H]≤-2.5dex, we show that this picture is incomplete. We
find that 31 per cent of the stars that currently reside spatially in
the disc (|Z|≥3kpc) do not venture outside of the disc plane
throughout their orbit. Moreover, this sample shows strong statistical
evidence (at the 5.0σ level) of asymmetry in their kinematics,
favouring prograde motion. The discovery of this population implies
that a significant fraction of stars with iron abundances
[Fe/H]≤-2.5dex merged into, formed within, or formed concurrently
with the MW disc and that the history of the disc was quiet enough to
allow them to retain their disc-like orbital properties, challenging
theoretical and cosmological models.
Description:
The Pristine sample is composed of 576 genuine very metal-poor (VMP)
stars, of which 360 with [Fe/H]≤-2.5dex, 66 are extremely metal-poor
(EMP) stars ([Fe/H]←3.0dex), and none are ultra metal-poor (UMP). The
sample spans a magnitude range of 11.5≤G≤16.5mag.
The Lamost sample (from LAMOST DR3) is composed of 4838 very
metal-poor (VMP) stars, of which 667 have [Fe/H]≤-2.5dex, 41 are
extremely metal-poor (EMP), and none are ultra metal-poor (UMP).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
pristine.dat 593 576 Pristine sample
lamost.dat 764 4838 LAMOST sample
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/153 : LAMOST DR4 catalogs (Luo+, 2018)
J/MNRAS/490/2241 : Spectroscopy of Pristine EMP star candidates (Aguado+, 2019)
Byte-by-byte Description of file: pristine.dat
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Bytes Format Units Label Explanations
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1- 17 F17.13 deg RAdeg Right ascension (J2000)
19- 34 F16.13 deg DEdeg Declination (J2000)
36- 56 F21.17 deg GLON Galactic longitude
58- 78 E21.17 deg E_GLON Error on GLON (positive value)
80-100 E21.17 deg e_GLON Error on GLON (negative value)
102-120 F19.15 deg GLAT Galactic latitude
122-142 E21.17 deg E_GLAT Error on GLAT (positive value)
144-164 E21.17 deg e_GLAT Error on GLAT (negative value)
166-188 F23.16 kpc.km/s Jphi Azimuthal action
190-210 F21.16 kpc.km/s E_Jphi Error on Jphi (positive value)
212-231 F20.15 kpc.km/s e_Jphi Error on Jphi (negative value)
233-252 E20.18 kpc.km/s Jr Radial action
254-273 E20.17 kpc.km/s E_Jr Error on Jr (positive value)
275-294 E20.17 kpc.km/s e_Jr Error on Jr (negative value)
296-315 F20.15 kpc.km/s Jz Vertical action
317-337 F21.16 kpc.km/s E_Jz Error on Jz (positive value)
339-359 F21.16 kpc.km/s e_Jz Error on Jz (negative value)
361-380 F20.16 kpc zmax Maximun height above the plane
382-402 F21.17 kpc E_zmax Error on zmax (positive value)
404-425 F22.18 kpc e_zmax Error on zmax (negative value)
427-445 I19 --- GaiaDR2 Gaia DR2 source_id
447-461 F15.11 deg RAGdeg Gaia DR2 right ascension (ICRS) at
Ep=2015.5
463-468 F6.4 mas e_RAGdeg Rms uncertainty on RAGdeg
470-483 F14.11 deg DEGdeg Gaia DR2 declination (ICRS) at Ep=2015.5
485-490 F6.4 mas e_DEGdeg Rms uncertainty on DEGdeg
492-498 E7.4 mas plx Gaia DR2 Parallax
500-505 F6.4 mas e_plx Gaia DR2 Parallax error
507-514 F8.3 mas/yr pmRA Gaia DR2 proper motion along RA
516-520 F5.3 mas/yr e_pmRA Rms uncertainty on pmRA
522-528 F7.3 mas/yr pmDE Gaia DR2 proper motion along DE
530-534 F5.3 mas/yr e_pmDE Rms uncertainty on pmDE
536-541 F6.3 Mpc Dist Distance
543-554 F12.10 Mpc e_Dist Rms uncertainty on Dist
556-565 F10.5 km/s RV Radial velocity
567-573 F7.4 km/s e_RV Rms uncertainty on RV
575-593 F19.16 [-] [Fe/H] Metallicity [Fe/H] from FERRE
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Byte-by-byte Description of file: lamost.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 F17.13 deg RAdeg Right ascension (J2000)
19- 34 F16.13 deg DEdeg Declination (J2000)
36- 56 F21.17 deg GLON Galactic longitude
58- 78 E21.17 deg E_GLON Error on GLON (positive value)
80-100 E21.17 deg e_GLON Error on GLON (negative value)
102-122 F21.17 deg GLAT Galactic latitude
124-144 E21.17 deg E_GLAT Error on GLAT (positive value)
146-166 E21.17 deg e_GLAT Error on GLAT (negative value)
168-191 F24.16 kpc.km/s Jphi Azimuthal action
193-213 F21.15 kpc.km/s E_Jphi Error on Jphi (positive value)
215-236 F22.16 kpc.km/s e_Jphi Error on Jphi (negative value)
238-258 E21.19 kpc.km/s Jr Radial action
260-279 E20.17 kpc.km/s E_Jr Error on Jr (positive value)
281-300 E20.17 kpc.km/s e_Jr Error on Jr (negative value)
302-325 F24.17 kpc.km/s Jz Vertical action
327-349 F23.17 kpc.km/s E_Jz Error on Jz (positive value)
351-373 F23.17 kpc.km/s e_Jz Error on Jz (negative value)
375-396 F22.17 kpc zmax Maximun height above the plane
398-419 F22.18 kpc E_zmax Error on zmax (positive value)
421-443 F23.18 kpc e_zmax Error on zmax (negative value)
445-484 A40 --- SpName LAMOST spectrum name
486-491 F6.1 K TeffLi Effective temperature from Li
493-497 F5.1 K e_TeffLi Rms uncertainty on TeffLi
499-503 F5.2 [-] [Fe/H]Li Metallicity from Li
505-509 F5.2 [-] [Fe/H]pub Metallicity from literature
511-518 F8.2 [-] e_[Fe/H]pub ?=-9999 Rms uncertainty on [Fe/H]pub
520-538 I19 --- GaiaDR2 Gaia DR2 source_id
540-554 F15.11 deg RAGdeg Gaia DR2 right ascension (ICRS) at
Ep=2015.5
556-574 F19.17 mas e_RAGdeg Rms uncertainty on RAGdeg
576-589 F14.11 deg DEGdeg Gaia DR2 declination (ICRS) at Ep=2015.5
591-610 F20.18 mas e_DEGdeg Rms uncertainty on DEGdeg
612-630 E19.17 mas plx Gaia DR2 Parallax
632-650 F19.17 mas e_plx Gaia DR2 Parallax error
652-672 F21.16 mas/yr pmRA Gaia DR2 proper motion along RA
674-692 F19.17 mas/yr e_pmRA Rms uncertainty on pmRA
694-713 F20.15 mas/yr pmDE Gaia DR2 proper motion along DE
715-732 F18.16 mas/yr e_pmDE Rms uncertainty on pmDE
734-751 F18.15 Mpc Dist Distance
753-764 F12.10 Mpc e_Dist Rms uncertainty on Dist
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History:
From electronic version of the journal
References:
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(End) Ana Fiallos [CDS] 28-Jul-2023