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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 (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:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 43 212 Mid-IR colours and metallicities for MW, LMC and SMC Cepheids
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
Bytes Format Units Label Explanations
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
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 28-Jul-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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