Galactic Cepheids with Spitzer: I. Leavitt Law and Colors

Abstract

Classical Cepheid variable stars have been important indicators of extragalactic distance and Galactic evolution for over a century. The Spitzer Space Telescope has opened the possibility of extending the study of Cepheids into the mid- and far-infrared, where interstellar extinction is reduced. We have obtained photometry from images of a sample of Galactic Cepheids with the IRAC and MIPS instruments on Spitzer. Here we present the first mid-infrared period-luminosity relations for Classical Cepheids in the Galaxy, and the first ever Cepheid period-luminosity relations at 24 and 70 um. We compare these relations with theoretical predictions, and with period-luminosity relations obtained in recent studies of the Large Magellanic Cloud. We find a significant period-color relation for the [3.6]-[8.0] IRAC color. Other mid-infrared colors for both Cepheids and non-variable supergiants are strongly affected by variable molecular spectral features, in particular deep CO absorption bands. We do not find strong evidence for mid-infrared excess caused by warm (~500 K) circumstellar dust. We discuss the possibility that recent detections with near-infrared interferometers of circumstellar shells around delta Cep, l Car, Polaris, Y Oph and RS Pup may be a signature of shocked gas emission in a dust-poor wind associated to pulsation-driven mass loss.

Accepted by The Astrophysical Journal on Nov 11, 2009

References in corpus (18)

• Direct Detection of the Close Companion of Polaris with the Hubble Space Telescope
• The influence of chemical composition on the properties of Cepheid stars. II-The iron content
• A new calibration of Galactic Cepheid Period-Luminosity relations from B to K bands, and a comparison to LMC PL relations
• Cepheid Parallaxes and the Hubble Constant
• Outflows from Massive YSOs as Seen with the Infrared Array Camera
• The Formation and Evolution of Planetary Systems: Description of the Spitzer Legacy Science Database
• High resolution spectroscopy for Cepheids distance determination. II. A period- projection factor relation
• High resolution spectroscopy for Cepheids distance determination. III. A relation between gamma-velocities and gamma-asymmetries
• Classical Cepheid Pulsation Models. XI. Effects of convection and chemical composition on the Period-Luminosity and Period-Wesenheit relations
• New period-luminosity and period-color relations of classical Cepheids: III. Cepheids in SMC
• Period-Luminosity Relations Derived from the OGLE-III Fundamental Mode Cepheids
• Extended envelopes around Galactic Cepheids III. Y Oph and alpha Per from near-infrared interferometry with CHARA/FLUOR
• Spitzer/IRAC Limits to Planetary Companions of Fomalhaut and epsilon Eridani
• Photometry using the Infrared Array Camera on the Spitzer Space Telescope
• The Period-Luminosity Relation for the Large Magellanic Cloud Cepheids Derived from Spitzer Archival Data
• The long-period Galactic Cepheid RS Puppis - I. A geometric distance from its light echoes
• The Cepheid Period-Luminosity Relation at Mid-Infrared Wavelengths: I. First-Epoch LMC Data
• Massive Star Multiplicity: The Cepheid W Sgr

Cited by in corpus (43)

• Final Targeting Strategy for the SDSS-IV APOGEE-2N Survey
• On the distance of the Magellanic Clouds using Cepheid NIR and optical-NIR Period Wesenheit Relations
• The Carnegie Hubble Program: The Leavitt Law at 3.6 and 4.5 micron in the Milky Way
• The Carnegie Hubble Program: The Leavitt Law at 3.6 μm and 4.5 μm in the Large Magellanic Cloud
• The Cepheid mass discrepancy and pulsation-driven mass loss
• The panchromatic view of the Magellanic Clouds from Classical Cepheids. I. Distance, Reddening and Geometry of the Large Magellanic Cloud disk
• On the evolutionary and pulsation mass of Classical Cepheids: III. the case of the eclipsing binary Cepheid CEP0227 in the Large Magellanic Cloud
• The Carnegie Hubble Program
• New NIR light-curve templates for classical Cepheids
• An Infrared Nebula Associated with Delta Cephei: Evidence of Mass Loss?
• Period-luminosity relations of type II Cepheids in the Magellanic Clouds
• New Evidence for Mass Loss from delta Cephei from HI 21-cm Line Observations
• Galactic Cepheids with Spitzer: II. Search for Extended Infrared Emission
• A Preliminary Calibration of the RR Lyrae Period-Luminosity Relation at Mid-Infrared Wavelengths: WISE Data
• A Global Physical Model for Cepheids
• The Near-infrared Optimal Distances Method Applied to Galactic Classical Cepheids Tightly Constrains Mid-infrared Period--Luminosity Relations
• On the Application of Wesenheit Function in Deriving Distance to Galactic Cepheids
• High-precision distance measurements with classical pulsating stars
• On the distance of the globular cluster M4 (NGC 6121) using RR Lyrae stars: II. Mid-infrared period-luminosity relations
• Thermal infrared properties of classical and type II Cepheids Diffraction limited 10 microns imaging with VLT/VISIR
• The Carnegie Chicago Hubble Program: The Mid-Infrared Colours of Cepheids and the Effect of Metallicity on the CO Band-head at $4.6\mu$m
• Extended envelopes around Galactic Cepheids IV. T Monocerotis and X Sagittarii from mid-infrared interferometry with VLTI/MIDI
• Current Challenges in Cepheid Distance Calibrations Using Gaia EDR3
• Cepheid limb darkening, angular diameter corrections, and projection factor from static spherical model stellar atmospheres
• Testing Mass Loss in Large Magellanic Cloud Cepheids using Infrared and Optical Observations II. Predictions and Tests of the OGLE-III Fundamental-Mode Cepheids
• Analysing the spectral energy distributions of Galactic classical Cepheids
• The Mid-Infrared Period-Luminosity Relations for the Small Magellanic Cloud Cepheids Derived from Spitzer Archival Data
• Mid-infrared Period-Luminosity Relations of RR Lyrae Stars Derived from the WISE Preliminary Data Release
• Period-Luminosity Relations for Cepheid Variables: From Mid-Infrared to Multi-Phase
• Extended envelopes around Galactic Cepheids. V. Multi-wavelength and time-dependent analysis of IR excess
• On the Form of the Spitzer Leavitt Law and its Dependence on Metallicity
• Updated 24 $\mu \mathrm{m}$ Period-Luminosity Relation Derived from Galactic Cepheids
• Theoretical Cepheid Period-Luminosity And Period-Color Relations In Spitzer IRAC Bands
• Young and Intermediate-age Distance Indicators
• New classical Cepheids in the inner part of the northern Galactic disk and their kinematics
• The Milky Way as Seen by Classical Cepheids I: Distances Based on Mid-infrared Photometry
• Cepheid Period-Luminosity Relation from the AKARI Observations
• A Search for Mass Loss on the Cepheid Instability Strip using HI 21-cm Line Observations
• On the nature of faint mid-infrared sources in M33
• X-rays in Cepheids: XMM-Newton Observations of $\eta$ Aql
• Period-Luminosity Relations for Small Magellanic Cloud Cepheid Based on AKARI Archival Data
• Asteroseismology, standard candles and the Hubble Constant: what is the role of asteroseismology in the era of precision cosmology?
• Changing CO Bands in Near-IR Spectra of CP Cephei