J/MNRAS/495/2858 Carbon stars as standard candles. I. (Ripoche+, 2020)
Carbon stars as standard candles:
I. The luminosity function of carbon stars in the Magellanic Clouds.
Ripoche P., Heyl J., Parada J., Richer H.
<Mon. Not. R. Astron. Soc., 495, 2858-2866 (2020)>
=2020MNRAS.495.2858R 2020MNRAS.495.2858R (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Stars, carbon ; Photometry, infrared
Keywords: catalogues - stars: carbon -
Hertzsprung-Russell and colour-magnitude diagrams -
stars: luminosity function, mass function - Magellanic Clouds
Abstract:
Our goal in this paper is to derive a carbon-star luminosity function
that will eventually be used to determine distances to galaxies at
50-60 Mpc and hence yield a value of the Hubble constant. Cool N-type
carbon stars exhibit redder near-infrared colours than oxygen-rich
stars. Using Two Micron All Sky Survey near-infrared photometry and
the Gaia Data Release 2, we identify carbon stars in the Magellanic
Clouds (MC) and the Milky Way (MW). Carbon stars in the MC appear as a
distinct horizontal feature in the near-infrared ((J-Ks)0, MJ)
colour-magnitude diagram. We build a colour selection
(1.4<(J-Ks)0<2) and derive the luminosity function of the
colour-selected carbon stars. We find the median absolute magnitude
and the dispersion, in the J band, for the Large and the Small
Magellanic Clouds (LMC/SMC) to be, respectively, (MJ=-6.284±0.004
and σ=0.352±0.005) and (MJ=-6.160±0.015 and
σ=0.365±0.014). The difference between the MC may be explained
by the lower metallicity of the SMC, but in any case it provides
limits on the type of galaxy whose distance can be determined with
this technique. To account for metallicity effects, we developed a
composite magnitude, named C, for which the error-weighted mean C
magnitude of the MC are equal. Thanks to the next generation of
telescopes (JWST, ELT, and TMT), carbon stars could be detected in
MC-type galaxies at distances out to 50-60Mpc. The final goal is to
eventually try and improve the measurement of the Hubble constant
while exploring the current tensions related to its value.
Description:
These catalogues of stars in the Magellanic Clouds were obtained as
described in the paper.
These catalogues use data from GAIA DR2 and 2MASS. The data presented
here can be used to construct the luminosity function of carbon stars
in each of the Magellanic Clouds.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
lmc2mass.dat 98 310187 Catalogue of stars in the LMC
smc2mass.dat 98 33372 Catalogue of stars in the SMC
--------------------------------------------------------------------------------
See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
Byte-by-byte Description of file: lmc2mass.dat smc2mass.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 unique source identifier
21- 39 F19.16 deg RAdeg Right ascension (ICRS) at Ep=J2015.5
41- 59 F19.15 deg DEdeg Declination (ICRS) at Ep=2015.5
61- 66 F6.3 mag Jmag 2MASS J magnitude
68- 73 F6.3 mag Hmag 2MASS H magnitude
75- 80 F6.3 mag Kmag 2MASS Ks magnitude
82- 86 F5.3 mag e_Jmag 2MASS J total magnitude uncertainty
88- 92 F5.3 mag e_Hmag 2MASS H total magnitude uncertainty
94- 98 F5.3 mag e_Kmag 2MASS Ks total magnitude uncertainty
--------------------------------------------------------------------------------
Acknowledgements:
Paul Ripoche, pripoche(at)alum.ubc.ca
(End) Patricia Vannier [CDS] 08-Dec-2021