J/A+A/633/A135 Solar neighbourhood carbon stars properties (Abia+, 2020)
Properties of carbon stars in the solar neighbourhood based on
Gaia DR2 astrometry.
Abia C., de Laverny P., Cristallo S., Kordopatis G., Straniero O.
<Astron. Astrophys. 633, A135 (2020)>
=2020A&A...633A.135A 2020A&A...633A.135A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Stars, carbon ; Photometry ; Radial velocities
Keywords: stars: late type - stars: carbon - techniques: photometry - astrometry
Abstract:
Stars evolving along the Asymptotic Giant Branch can become
carbon-rich in the final part of their evolution. The detailed
description of their spectra has led to the definition of several
spectral types, namely: N, SC, J and R types. Up to now, differences
among them have been partially established only on the basis of their
chemical properties.
An accurate determination of the luminosity function (LF) and
kinematics together with their chemical properties is extremely
important for testing the reliability of theoretical models and
establishing on a solid basis the stellar population membership of the
different carbon star types.
Using Gaia Data Release 2 (Gaia DR2) astrometry, we determine the LF
and kinematic properties of a sample of 210 carbon stars with
different spectral types in the Solar neighbourhood, including some
R-hot stars, with measured parallaxes better than 20%. Their spatial
distribution and velocity components are also derived. Furthermore,
the use of the infrared Wesenheit function allows us to identify the
different spectral types in a Gaia-2MASS diagram.
We find that the combined LF of N- and SC-type stars are consistent
with a Gaussian distribution peaking at Mbol~-5.2mag. The resulting
LF however shows two tails at lower and higher luminosities more
extended than those previously found, indicating that AGB carbon stars
with Solar metallicity may reach Mbol~-6.0mag. This contrasts
with the narrower LF derived in Galactic carbon Miras from previous
studies.We find that J-type stars are about half a magnitude fainter
on average than N- and SC-type stars, while R-hot stars are half a
magnitude brighter than previously found although, in any case,
fainter by several magnitudes than the rest of carbon types. Part of
these differences are due to systematically lower parallaxes measured
by Gaia DR2 with respect to Hipparcos ones, in particular for sources
with parallax Plx<1mas. The Galactic spatial distribution and
velocity components of the N-, SC- and J-type stars are very similar,
while about 30% of the R-hot stars in the sample are located at
distances larger than ∼ 500 pc from the Galactic Plane, and show a
significant drift with respect to the local standard of rest.
The LF derived for N- and SC-type in the Solar neighbourhood fully
agrees with the expected luminosity of stars of 1.5-3M ☉ on the
AGB. On a theoretical basis, the existence of an extended low
luminosity tail would require a contribution of extrinsic low mass
carbon stars, while the high luminosity one would imply that stars
with mass up to ∼5M ☉ may become carbon stars on the AGB.
J-type stars not only differ significantly in their chemical
composition with respect to the N- and SC-types but also in their LF,
which reinforces the idea that these carbon stars belong to a
different type whose origin is still unknown. The derived
luminosities of R-hot stars make these stars unlikely to be in the
red-clump as previously claimed. On the other hand, the derived
spatial distribution and kinematic properties, together with their
metallicity, indicate that most of the N-, SC- and J-type stars belong
to the thin disc population, while a significant fraction of R-hot
stars show characteristics compatible with the thick disc.
Description:
The analysis is based on Gaia DR2 data for a sample of luminous red
giant carbon stars of N-, SC-, J- and R-hot spectral types belonging
to the Solar neighbourhood, from the survey by Claussen et al.
(1987ApJS...65..385C 1987ApJS...65..385C).
This sample contains Galactic 214 carbon stars. Some additional carbon
stars with already well-determined photospheric characteristics and,
in particular, chemical properties were added.
The criterion on Gaia DR2 parallax e_Plx/Plx≤0.2 was imposed, in
order to derive accurate luminosities and kinematic properties. The
resulting sample contains 218 stars, including variables of Mira,
irregular and semi-regular types.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 111 218 Derived data for the sample stars
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Star SIMBAD star name
13- 31 I19 --- GDR2 Gaia DR2 source identification
33- 37 F5.2 mag Jmag0 Extinction corrected J magnitude
39- 43 F5.2 mag Ksmag0 Extinction corrected K short magnitude
45- 48 F4.2 mag BCKs0 Bolometric correction in K short
50- 55 F6.1 pc Dist Distance
57- 61 F5.2 mag Mbol Absolute bolometric magnitude
63- 67 F5.1 km/s RV ? Radial velocity
69- 73 F5.2 kpc Rgal Galactocentric distance
75- 79 F5.2 kpc Z Distance above/below the Galactic plane
81- 86 F6.1 km/s Vr ? Radial velocity component
88- 92 F5.1 km/s Vtheta ? Rotational velocity component
94- 99 F6.1 km/s Vz ? Vertical velocity component
101-104 F4.2 --- e ? Orbital eccentricity
106 I1 --- Pmemb [0/2]? Membership probability (1)
108 I1 --- Ref [1/8]? References for radial velocity (2)
110-111 A2 --- SpType Spectral type
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Note (1): Membership probability as follows:
0 = higher than 80% for thin disc
1 = thick disk
2 = halo
Note (2): References for radial velocities as follows:
1 = Gontcharov (2006A&AT...25..145G 2006A&AT...25..145G)
2 = Menzies, J.W. et al. (2006MNRAS.369..783M 2006MNRAS.369..783M, Cat. J/MNRAS/369/783)
3 = Gaia Collaboration et al. (2018A&...616A...1G, Cat. I/345/)
4 = Duflot, M. et al. (1995A&AS..114..269D 1995A&AS..114..269D, Cat. III/190)
5 = Kharchenko, N.V. et al. (2007AN....328..889K 2007AN....328..889K, Cat. J/AN/328/889)
6 = Catchpole, R.M. & Feast, M. (1971MNRAS.154..197C 1971MNRAS.154..197C)
7 = Kunder, A. et al. (2017AJ....153...75K 2017AJ....153...75K, Cat. III/279
8 = Feast, M. & Whitelock, P.A. (2000MNRAS.317..460F 2000MNRAS.317..460F, Cat. J/MNRAS/317/460)
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Acknowledgements:
Carlos Abia, cabia(at)ugr.es
(End) Carlos Abia [UGR, Spain], Patricia Vannier [CDS] 05-Dec-2019