J/MNRAS/459/1170 Coulour-Period relation for Cepheids (Scowcroft+, 2016)
The Carnegie Chicago Hubble Program: the mid-infrared colours of Cepheids and
the effect of metallicity on the CO band-head at 4.6µm.
Scowcroft V., Seibert M., Freedman W.L., Beaton R.L., Madore B.F.,
Monson A.J., Rich J.A., Rigby J.R.
<Mon. Not. R. Astron. Soc., 459, 1170-1178 (2016)>
=2016MNRAS.459.1170S 2016MNRAS.459.1170S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Photometry, infrared ; Abundances, [Fe/H]
Keywords: stars: abundances - stars: variables: Cepheids - infrared: stars
Abstract:
We compare mid-infrared (IR) 3.6 and 4.5µm Warm Spitzer
observations for Cepheids in the Milky Way and the Large and Small
Magellanic Clouds. Using models, we explore in detail the effect of
the CO rotation-vibration band-head at 4.6µm on the mid-IR
photometry. We confirm the temperature sensitivity of the CO band-head
at 4.6µm and find no evidence for an effect at 3.6µm. We
compare the ([3.6]-[4.5]) period-colour relations in the MW, LMC
and SMC. The slopes of the period-colour relations for the three
galaxies are in good agreement, but there is a trend in zero-point
with metallicity, with the lowest metallicity Cepheids having redder
mid-IR colours. Finally, we present a colour-[Fe/H] relation based on
published spectroscopic metallicities. This empirical relation,
calibrated to the metallicity system of Genovali et al., demonstrates
that the ([3.6]-[4.5]) colour provides a reliable metallicity
indicator for Cepheids, with a precision comparable to current
spectroscopic determinations.
Description:
In this work, we bring together the mid-IR, Warm Spitzer observations
taken by the CCHP (Monson et al., 2012, Cat. J/ApJ/759/146, Scowcroft
et al., 2011, Cat. J/ApJ/743/76, Scowcroft et al., 2016, Cat.
J/ApJ/816/49), with spectroscopic metallicities compiled in genovali
et al. (2014. Cat. J/A+A/566/A37).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 43 212 Mid-IR colours and metallicities for MW, LMC
and SMC Cepheids
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See also:
J/ApJ/743/76 : Spitzer photometry of LMC Cepheids (Scowcroft+, 2011)
J/ApJ/759/146 : Spitzer/IRAC photometry for 37 Galactic Cepheids (Monson+ 2012)
J/A+A/566/A37 : Iron abundances for 42 Galactic Cepheids (Genovali+, 2014)
J/ApJ/816/49 : Spitzer/IRAC observations of SMC Cepheids (Scowcroft+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Cepheid ID
15- 20 F6.4 [d] logP Period
22- 27 F6.3 mag [3.6]-[4.5] Mid-ID [3.6]-[4.5] colour index
29- 33 F5.3 mag e_[3.6]-[4.5] rms uncertainty on [3.6]-[4.5]
35- 39 F5.2 [-] [Fe/H] ?=- Metallicity
41- 43 A3 --- Gal Galaxy name
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 28-Jul-2017