J/A+A/645/A69 PRM catalogue of halo MS stars (Koppelman+, 2021)
The reduced proper motion selected halo:
Methods and description of the catalogue.
Koppelman H.H., Helmi A.
<Astron. Astrophys. 645, A69 (2021)>
=2021A&A...645A..69K 2021A&A...645A..69K (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, distances ; Proper motions
Keywords: Galaxy: structure - Galaxy: halo - Galaxy: kinematics and dynamics
Abstract:
The Gaia mission has provided the largest ever astrometric chart of
the Milky Way. Using it to map the Galactic halo is helpful for
disentangling its merger history. The identification of halo stars in
Gaia DR2 with reliable distance estimates requires special methods
because such stars are typically farther away and scarce. We applied
the reduced proper motion (RPM) method to identify halo main sequence
stars on the basis of Gaia photometry and proper motions. Using the
colour-absolute-magnitude relation for this type of star, we
calculated photometric distances. Our selection results in a set of
107 tentative main sequence halo stars with typical distance
uncertainties of 7% and with median velocity errors of 20km/s. The
median distance of our sample is ∼4.4kpc, with the faintest stars
located at ∼16kpc. The spatial distribution of the stars in our
sample is centrally concentrated. A visual inspection of the mean
velocities of stars on the sky reveals large-scale patterns as well as
clear imprints of the GD-1 stream and tentative hints of the Jhelum
and Leiptr streams. Incompleteness and selection effects limit our
ability to interpret the patterns reliably as well as to identify new
substructures. We define a pseudo-velocity space by setting the
line-of-sight velocities of our sample stars to zero. In this space,
we recover several known structures such as the footprint of
Gaia-Enceladus (i.e. the Gaia-Sausage) as well as the Helmi Streams
and some other retrograde substructures (Sequoia, Thamnos). We show
that the two-point velocity correlation function reveals significant
clustering on scales smaller than 100km/s of a similar amplitude as
found for the 6D Gaia halo sample. This clumping of stars in velocity
space might hint at the presence of nearby streams that are
predominantly phase-mixed. A spectroscopic follow-up of our halo main
sequence sample is bound to yield unprecedented views of Galactic
history and dynamics. In future Gaia data releases, the level of
systematics will be reduced and the astrometry will be more precise,
which will allow for the identification of more substructures at
larger distances.
Description:
Gaia DR2 source_ids of sources that are identified as Main Sequence
halo stars in the RPM diagram. For each source the source_id is
included together with the RPM value (Hg), extinction parameters (Av,
E(B-V), and the extinction fraction), the Gaia DR2 RUWE parameter, and
the photometric distance and its uncertainty.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 246 11711399 Reduced proper motion (RPM) catalog
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
I/349 : StarHorse, Gaia DR2 photo-astrometric distances (Anders+, 2019)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR2 Gaia DR2 source_id
21- 44 E24.17 mag E(B-V) Reddening E(B-V) (from Schlegel et al.,
1998ApJ...500..525S 1998ApJ...500..525S)
46- 69 E24.17 mag Av Av extinction (from E(B-V))
71- 94 E24.17 --- RUWE Gaia DR2 RUWE parameter
96-119 E24.17 mag Hg Reduced proper motion (see Eq.5)
121-144 E24.17 kpc DistPhot Photometric distance
146-169 E24.17 kpc e_DistPhot Photometric distance uncertainty
171-194 E24.17 --- Extfrac Fraction of full extinction
196-210 F15.11 deg RAdeg Gaia DR2 right ascension (ICRS)
at Ep=2015.5 (1)
212-226 F15.11 deg DEdeg Gaia DR2 declination (ICRS) at Ep=2015.5 (1)
228-246 I19 --- --- Gaia DR2 source_id
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Note (1): Gaia DR2 positions added by CDS, from Gaia DR2 (Cat. I/345).
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Acknowledgements:
Helmer H. Koppelman, koppelman(at)astro.rug.nl
(End) H. Koppelman [Kapteyn Astron. Inst.], P. Vannier [CDS] 10-Nov-2020