J/A+A/638/A104 Gaia DR2 candidate RR Lyrae of Sgr stream & dwarf (Ramos+, 2020)
Full 5D characterisation of the Sagittarius stream with Gaia DR2 RR Lyrae.
Ramos P., Mateu C., Antoja T., Helmi A., Castro-Ginard A., Balbinot E.,
Carrasco J.M.
<Astron. Astrophys. 638, A104 (2020)>
=2020A&A...638A.104R 2020A&A...638A.104R (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, variable ; Stars, dwarfs ; Proper motions
Keywords: Galaxy: halo - stars: variables: RR Lyrae - galaxies: dwarf -
astrometry
Abstract:
The Sagittarius (Sgr) stream is one of the best tools that we
currently have to estimate the mass and shape of our Galaxy. However,
assigning membership and obtaining the phase-space distribution of
the stars that form the tails is quite challenging. Our goal is to
produce a catalogue of RR Lyrae stars of Sgr and obtain an empiric
measurement of the trends along the stream in sky position, distance
and tangential velocities. We generate two initial samples from the
Gaia DR2 RR Lyrae catalogue: one, selecting only the stars within
±20° of the orbital plane of Sagittarius (Strip) and the other,
the result of applying the Pole Count Map (nGC3) algorithm. We then
use the model-independent, deterministic method developed in this work
to remove most of the contamination by detecting and isolating the
stream in distance and proper motions. The output is two empiric
catalogues: the Strip sample (higher-completeness, lower-purity) which
contains 11677 stars, and the nGC3 sample (higher-purity,
lower-completeness) with 6608 stars. We characterise the changes along
the stream in all the available dimensions, the 5 astrometric ones
plus the metallicity, covering more than 2πrad in the sky and
obtain new estimates for the apocentres and the mean [Fe/H] of the RR
Lyrae population. Also, we show the first map of the two components of
the tangential velocity, thanks to the combination of distances and
proper motions. Finally, we detect the bifurcation in the leading arm
and report no significant difference between the two branches, either
in metallicity, kinematics or distance. We provide the largest sample
of RR Lyrae candidates of Sgr, which can be used as an input for a
spectroscopic follow-up or as a reference for the new generation of
models of the stream through the interpolators in distance and
velocity that we have constructed.
Description:
This list contains 11721 RRLyrae stars which we have selected from the
Gaia DR2 + PanSTARRS1 (PS1) catalogues as being probable members of
the Sagittarius stream and dwarf. The selection is based on all 5
available dimensions: position on the sky, distance and proper
motions. Although a certain degree of contamination is to be expected,
we provide two subsamples: a purer but more incomplete (nGC3 sample)
and a more complete but also more contaminated (Strip sample). For
each star we provide source_id, Gaia 'G' magnitude, sky position and
proper motions in 3 different reference systems (ICRS, Galactic and
Sagittarius - as defined in Belokurov et al. 2014MNRAS.437..116B 2014MNRAS.437..116B),
distance (estimated from Gaia photometry) and tangential velocities
along and across the orbital plane of Sagittarius. For all quantities
expect positions and magnitudes we also provide the associated
uncertainties. Finally, we include a column to specify the source
catalogue (SOS table, PS1 and/or the Variable Catalogue from Gaia) and
another specifying to which sample the stars belongs to (nGC3, Strip
or both). More material (interpolation used to obtain smooth curves
given as a Python pickle, animations, etc.) are available at:
https://services.fqa.ub.edu/sagittarius
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablee1.dat 262 11721 Candidate RR Lyrae stars of the Sagittarius
stream and dwarf from Gaia DR2
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)
J/A+A/622/A60 : Gaia DR2 misclassified RR Lyrae list (Clementini+, 2019)
Byte-by-byte Description of file: tablee1.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR2 Gaia DR2 Unique source identifier
21- 27 F7.4 mag Gmag G-band mean magnitude (photgmean_mag)
29- 33 F5.2 kpc d Distance
35- 38 F4.2 kpc e_d Error on distance
40- 54 F15.11 deg RAdeg Right ascension (ICRS) at Ep=2015.5
56- 70 F15.11 deg DEdeg Declination (ICRS) at Ep=2015.5
72- 80 F9.3 mas/yr pmRA Proper motion in right ascension direction,
pmRA*cosDE (J2015.5)
82- 86 F5.3 mas/yr e_pmRA Error in the Proper motion in right ascension
direction (J2015.5)
88- 96 F9.3 mas/yr pmDE Proper motion in declination direction
(J2015.5)
98-102 F5.3 mas/yr e_pmDE Error in the Proper motion in declination
direction (J2015.5)
104-117 F14.10 deg GLON Galactic longitude
119-132 F14.10 deg GLAT Galactic latitude
134-139 F6.3 mas/yr pmGLON Proper motion in Gal. longitude
141-145 F5.3 mas/yr e_pmGLON Error in proper motion in Gal. longitude
147-152 F6.3 mas/yr pmGLAT Proper motion in Gal. latitude
154-158 F5.3 mas/yr e_pmGLAT Error in proper motion in Gal. latitude
160-170 F11.6 deg GLONS Sagittarius longitude
(Belokurov, 2014MNRAS.437..116B 2014MNRAS.437..116B)
172-181 F10.6 deg GLATS Sagittarius latitude
(Belokurov, 2014MNRAS.437..116B 2014MNRAS.437..116B)
183-188 F6.3 mas/yr pmGLONS Proper motion in Sagittarius longitude
190-194 F5.3 mas/yr e_pmGLONS Error in proper motion in Sgr longitude
196-201 F6.3 mas/yr pmGLATS Proper motion in Sagittarius latitude
203-207 F5.3 mas/yr e_pmGLATS Error in proper motion in Sgr latitude
209-216 F8.2 km/s vL Velocity along Sgr. longitude
218-224 F7.2 km/s e_vL Error in velocity along Sgr longitude
226-232 F7.2 km/s vB Velocity along Sgr. latitude
234-240 F7.2 km/s e_vB Error in velocity along Sgr latitude
242-245 A4 --- SOStype Type of RR Lyr according to SOS classification
247-250 A4 --- PS1type Type of RR Lyr according to PS1 classification
252-255 A4 --- VCtype Type of RR Lyr according to the
Variable Catalogue
257-259 I3 --- inputCat [1/111] 3-bit that indicates the source
catalogue where the star is found (1)
261-262 I2 --- Sample [1/11] 2-bit that indicates in which sample
(nGC3 or Strip) the star has been found (2)
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Note (1): inputCat core as follows:
1 = found in catalog Variable Catalogue from Gaia (Cat. I/345)
10 = found in catalog PS1 (Cat. II/349)
100 = found in catalog SOS (Specific Objects Study, Clementini et al.,
Cat. J/A+A/622/A60)
11 = found in catalogs PS1 and Variable Catalogue from Gaia
101 = found in catalogs SOS and Variable Catalogue from Gaia
111 = found in the 3 catalogs, SOS, PS1 and Variable Catalogue from Gaia
Note (2): Sample code as follows:
1 = found in Strip sample
10 = found in nGC3 sample
11 = found in nGC3 and Strip sample
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Acknowledgements:
Pau Ramos, pramos(at)fqa.ub.edu
(End) Patricia Vannier [CDS] 27-Apr-2020