J/MNRAS/475/1680 Parameters of 1183 A and F stars (Harris+, 2018)
A and F stars as probes of outer Galactic disc kinematics.
Harris A., Drew J.E., Farnhill H.J., Monguio M., Gebran M., Wright N.J.,
Drake J.J., Sale S.E.
<Mon. Not. R. Astron. Soc., 475, 1680-1695 (2018)>
=2018MNRAS.475.1680H 2018MNRAS.475.1680H (SIMBAD/NED BibCode)
ADC_Keywords: Galactic plane ; Milky Way ; Radial velocities ;
Spectrophotometry ; Stars, early-type
Keywords: methods: observational - techniques: radial velocities -
Galaxy: disc - Galaxy: kinematics and dynamics
Abstract:
Previous studies of the rotation law in the outer Galactic disc have
mainly used gas tracers or clump giants. Here, we explore A and F
stars as alternatives: these provide a much denser sampling in the
outer disc than gas tracers and have experienced significantly less
velocity scattering than older clump giants. This first investigation
confirms the suitability of A stars in this role. Our work is based on
spectroscopy of roughly 1300 photometrically selected stars in the red
calcium-triplet region, chosen to mitigate against the effects of
interstellar extinction. The stars are located in two low Galactic
latitude sightlines, at longitudes l=118°, sampling strong
Galactic rotation shear, and l=178°, near the anticentre. With the
use of Markov Chain Monte Carlo parameter fitting, stellar parameters
and radial velocities are measured, and distances computed. The
obtained trend of radial velocity with distance is inconsistent with
existing flat or slowly rising rotation laws from gas tracers (Brand &
Blitz, 1993A&A...275...67B 1993A&A...275...67B, Cat J/A+A/275/67; Reid et al.,
2014ApJ...783..130R 2014ApJ...783..130R, Cat. J/ApJ/783/130). Instead, our results fit in
with those obtained by Huang et al. (2016MNRAS.463.2623H 2016MNRAS.463.2623H) from disc
clump giants that favoured rising circular speeds. An alternative
interpretation in terms of spiral arm perturbation is not straight
forward. We assess the role that undetected binaries in the sample and
distance error may have in introducing bias, and show that the former
is a minor factor. The random errors in our trend of circular velocity
are within ±5km/s.
Description:
Specto-photometrically determined parameters for 1183 A and F type
stars are presented. The stars are located in two pencil-beam
sightlines in the Galactic plane, at (l=118°, b=+2°) and
(l=178°, b=+1°). The stellar parameters and radial velocities
are determined from spectra using an Markov Chain Monte Carlo
parameter fitting routine. Spectro-photometric distances are
determined using these parameters combined with IPHAS photometry (also
presented) and Padova isochrones.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 261 1183 Stellar parameters and distances
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Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- ID Target ID (NNN.NN.NNN)
12- 26 F15.12 deg RAdeg Right ascension (J2000.0)
28- 40 F13.10 deg DEdeg Declination (J2000.0)
42- 54 F13.9 deg GLON Galactic longitude
56- 69 F14.12 deg GLAT Galactic latitude
71- 75 I5 K Teff Effective temperature, Teff
77- 80 I4 K e_Teff Teff negative error
82- 84 I3 K E_Teff Teff positive error
86- 90 F5.3 [cm/s2] logg Surface gravity, logg
92- 96 F5.3 [cm/s2] e_logg logg negative error
98-102 F5.3 [cm/s2] E_logg logg positive error
104-106 I3 km/s vsini Rotational velocity, vsini
108-109 I2 km/s e_vsini vsini negative error
111-113 I3 km/s E_vsini vsini positive error
115-121 F7.2 km/s RV Measured radial velocity
123-127 F5.2 km/s e_RV Measured radial velocity negative error
129-133 F5.2 km/s E_RV Measured radial velocity positive error
135-141 F7.2 km/s RVlsr Radial velocity corrected to LSR frame (1)
143-155 F13.10 mag rmag IPHAS apparent r magnitude
157-168 F12.10 mag e_rmag IPHAS apparent r magnitude error
170-182 F13.10 mag imag IPHAS apparent i magnitude
184-195 F12.10 mag e_imag IPHAS apparent i magnitude error
197-202 F6.3 mag iMAG Absolute i magnitude
204-208 F5.3 mag e_iMAG Absolute i magnitude error
210-216 F7.4 mag r-iint r-i intrinsic colour index
218-223 F6.4 mag e_r-iint r-i intrinsic colour index error
225-229 F5.3 mag/kpc Ai i band extinction
231-235 F5.3 mag/kpc e_Ai i band extinction error
237-242 F6.3 kpc Dist Heliocentric distance
244-248 F5.3 kpc e_Dist Heliocentric distance error
250-255 F6.3 mag DM Distance modulus
257-261 F5.3 mag e_DM Distance modulus error
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Note (1): The Solar motion adopted for correction to LSR frame is
(U, V, W)=(+11, +12, +7)km/s (Schonrich, Binney & Dehnen 2010MNRAS.403.1829S 2010MNRAS.403.1829S).
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Acknowledgements:
Amy Harris, a.harris7(at)herts.ac.uk
(End) Amy Harris [Hertfordshire Univ., UK], Patricia Vannier [CDS] 23-Nov-2018