J/A+A/701/A270 GaiaUnlimited. Milky Way red clump catalogue (Khanna+, 2025)
GaiaUnlimited: The old stellar disc of the Milky Way as traced by the red clump.
Khanna S., Yu J., Drimmel R., Poggio E., Cantat-Gaudin T., Castro-Ginard A.,
Kurbatov E., Belokurov V., Brown A., Fouesneau M., Casey A., Rix H.-W.
<Astron. Astrophys. 701, A270 (2025)>
=2025A&A...701A.270K 2025A&A...701A.270K (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Galactic center ; Populations, stellar ; Optical ;
Stars, distances
Keywords: stars: distances - Galaxy: disc - Galaxy: fundamental parameters -
Galaxy: structure
Abstract:
We present an exploration of the Milky Way's structural parameters
using an all-sky sample of RC giants to map the stellar density from
the Galactic disc beyond 3kpc. These evolved giants are considered to
be standard candles due to their low intrinsic variance in their
absolute luminosities, allowing us to estimate their distances with
reasonable confidence. We exploit all-sky photometry from the AllWISE
mid-infrared survey and the Gaia survey, along with astrometry from
Gaia Data Release 3 and recent 3D extinction maps, to develop a
probabilistic scheme in order to select with high confidence RC-like
stars. Our curated catalogue contains about 10 million sources, for
which we estimate photometric distances based on the WISE W1
photometry. We then derive the selection function for our sample,
which is the combined selection function of sources with both Gaia and
AllWISE photometry. Using the distances and accounting for the full
selection function of our observables, we are able to fit a two-disc,
multi-parameter model to constrain the scale height (hz), scale-length
(rd), flaring, and the relative mass ratios of the two disc
components. We illustrate and verify our methodology using mock
catalogues of RC stars. We find that the RC population is best
described by a flared disc with scale length rd=4.24±0.32kpc and
scale height at the Sun of hz(at Sun)=0.18±0.01kpc, and a shorter
and thicker disc with rd=2.66±0.11kpc, hz(at Sun)=0.48±0.11kpc,
with no flare. The thicker disc constitutes 66% of the RC stellar
mass beyond 3kpc, while the flared disc shows evidence of being
warped beyond 9kpc from the Galactic center. The residuals between
the predicted number density of RC stars from our axisymmetric model
and the measured counts show possible evidence of a two-armed spiral
perturbation in the disc of the Milky Way.
Description:
Red Clump sample used in the paper to constrain disc parameters.
Specifically, the sample used to make Figures 8/9 etc.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 131 8729562 Red clump catalog
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
II/328 : AllWISE Data Release (Cutri+ 2013)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 Gaia DR3 source_id
21- 35 F15.11 deg GLON Galactic longitude
37- 51 F15.11 deg GLAT Galactic latitude
53- 60 F8.5 mag Gmag Gaia DR3 G magnitude
62- 67 F6.3 mag W1mag AllWISE W1 magnitude
69- 83 F15.11 deg RAdeg Right Ascension (ICRS) at Ep=2016.0
85- 99 F15.11 deg DEdeg Declination (ICRS) at Ep=2016.0
101-109 I9 --- ALLWISE AllWISE ID
111-120 F10.7 kpc distw1 Red Clump distance estimate
122-131 F10.8 kpc e_distw1 Red Clump distance uncertainty estimate (1)
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Note (1): The distance uncertainty should be treated as a minimum estimate of
the true value.
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Acknowledgements:
Shourya Khanna, shourya.khanna(at)inaf.it
(End) Patricia Vannier [CDS] 11-Aug-2025