J/MNRAS/492/3408 Galactic disc RR Lyrae stars (Prudil+, 2020)
Evidence for Galactic disc RR Lyrae stars in the solar neighbourhood.
Prudil Z., Dekany I., Grebel E.K., Kunder A.
<Mon. Not. R. Astron. Soc. 492, 3408-3419 (2020)>
=2020MNRAS.492.3408P 2020MNRAS.492.3408P (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, variable ; Photometry
Keywords: Galaxy: disc - Galaxy: kinematics and dynamics -
stars: variables: RR Lyrae
Abstract:
We present a kinematical study of 314 RR Lyrae stars in the solar
neighbourhood using the publicly available photometric, spectroscopic,
and Gaia DR2 astrometric data to explore their distribution in the
Milky Way. We report an overdensity of 22 RR Lyrae stars in the solar
neighbourhood at a pericentre distance of between 5 and 9kpc from the
Galactic Centre. Their orbital parameters and their chemistry indicate
that these 22 variables share the kinematics and the [Fe/H] values of
the Galactic disc, with an average metallicity and tangential velocity
of [Fe/H]=-0.60dex and vtheta=241km/s, respectively. From the
distribution of the Galactocentric spherical velocity components, we
find that these 22 disc-like RR Lyrae variables are not consistent
with the Gaia Sausage (Gaia-Enceladus), unlike almost half of the
local RR Lyrae stars. Chemical information from the literature shows
that the majority of the selected pericentre-peak RR Lyrae variables
are alpha-poor, a property shared by typically much younger stars in
the thin disc. Using the available photometry, we rule out a possible
misclassification with the known classical and anomalous Cepheids. The
similar kinematic, chemical, and pulsation properties of these disc RR
Lyrae stars suggest they share a common origin. In contrast, we find
that the RR Lyrae stars associated with the Gaia- Enceladus based on
their kinematics and chemical composition show a considerable
metallicity spread in the old population (approximately 1dex).
Description:
A kinematical study of 314 RR Lyrae stars in the solar neighbourhood
using the publicly available photometric, spectroscopic, and Gaia DR2
astrometric data to explore their distribution in the Milky Way is
presented
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
rrdisk.dat 184 314 Galactic disc RR Lyrae stars
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
III/176 : RR Lyrae Metallicities (Layden 1994)
J/AJ/108/1016 : Kinematics of local RR lyrae stars. I. (Layden 1994)
J/MNRAS/435/3206 : Properties of field RR Lyrae variables (Dambis+, 2013)
Byte-by-byte Description of file: rrdisk.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name GCVS variable star designation
10 A1 --- n_Name [+*] Note on Name (1)
12- 18 F7.5 d Period Pulsation period
20- 24 F5.2 mag Vmag Apparent magnitude in V
26- 29 F4.2 mag e_Vmag Uncertainty on apparent magnitude in V
31- 37 F7.5 mag AmpV Amplitude in V band
39- 42 F4.2 --- R21 Fourier amplitude ratio R21
44- 47 F4.2 --- e_R21 Uncertainty on Fourier amplitude ratio R21
49- 52 F4.2 --- phi21 Fourier phase parameter phi21
54- 57 F4.2 --- e_phi21 Uncertainty on Fourier phase parameter phi21
59- 62 F4.2 --- R31 Fourier amplitude ratio R31
64- 67 F4.2 --- e_R31 Uncertainty on Fourier amplitude ratio R31
69- 72 F4.2 --- phi31 Fourier phase parameter phi31
74- 77 F4.2 --- e_phi31 Uncertainty on Fourier phase parameter phi31
79- 83 F5.2 --- [Fe/H] Metallicity
85- 89 F5.2 --- [Ca/Fe] ?=- Calcium abundance
91- 97 F7.2 km/s vR Galactocentric radial velocity
99-103 F5.2 km/s e_vR Uncertainty on Galactocentric radial velocity
105-111 F7.2 km/s vT Galactocentric tangential velocity
113-117 F5.2 km/s e_vT Uncertainty on Galactocentric tangential
velocity
119-125 F7.2 km/s vZ Galactocentric vertical velocity
127-131 F5.2 km/s e_vZ Uncertainty on Galactocentric vertical
velocity
133-137 F5.3 kpc rper Pericentric distance
139-143 F5.3 kpc e_rper Uncertainty on pericentric distance
145-150 F6.3 kpc zmax Maximum height from the Galactic plane
152-157 F6.3 kpc e_zmax Uncertainty on Maximum height from the
Galactic plane
159-163 F5.3 --- e Eccentricity
165-169 F5.3 --- e_e Uncertainty on eccentricity
171-177 F7.3 kpc rapo Apocentric distance
179-184 F6.3 kpc e_rapo Uncertainty on apocentric distance
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Note (1): Note as follows:
* = identified possible thin-disc stars
+ = RR Lyrae variables possibly kinematicaly associated with the
Gaia-Enceladus/Sausage
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Acknowledgements:
Zdenek Prudil, prudilz(at)ari.uni-heidelberg.de
(End) Zdenek Prudil [ARI, Germany], Patricia Vannier [CDS] 07-Mar-2020