The influence of chemical composition on the properties of Cepheid stars. II - The iron content ⋆

By M. Romaniello, F. Primas, M. Mottini, S. Pedicelli, B. Lemasle, G. Bono, P. François, M. Groenewegen, C. D. Laney. 2008

160 citations recorded by the source corpus.

Context. The Cepheid period-luminosity (PL) relation is unquestionably one of the most powerful tools at our disposal for determining the extragalactic distance scale. While significant progress has been made in the past few years towards its understanding and characterization both on the observational and theoretical sides, the debate on the influence that chemical composition may have on the PL relation is still unsettled. Aims. With the aim to assess the influence of the stellar iron content on the PL relation in the V and K bands, we have related the V -band and the K -band residuals from the standard PL relations of Freedman et al. (2001, ApJ, 553, 47) and Persson et al. (2004, AJ, 128, 2239), respectively, to [Fe/H]. Methods. We used direct measurements of the iron abundances of 68 Galactic and Magellanic Cepheids from FEROS and UVES high-resolution and high signal-to-noise spectra. Results. We find a mean iron abundance ([Fe/H]) about solar ($\sigma $= 0.10) for our Galactic sample (32 stars), ~-0.33 dex ( σ = 0.13) for the Large Magellanic Cloud (LMC) sample (22 stars) and ~-0.75 dex ( σ = 0.08) for the Small Magellanic Cloud (SMC) sample (14 stars). Our abundance measurements of the Magellanic Cepheids double the number of stars studied up to now at high resolution. The metallicity affects the V -band Cepheid PL relation and metal-rich Cepheids appear to be systematically fainter than metal-poor ones. These findings depend neither on the adopted distance scale for Galactic Cepheids nor on the adopted LMC distance modulus. Current data do not allow us to reach a firm conclusion concerning the metallicity dependence of the K -band PL relation. The new Galactic distances indicate a small effect, whereas the old ones support a marginal effect. Conclusions. Recent robust estimates of the LMC distance and current results indicate that the Cepheid PL relation is not Universal.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/6a5a517d67efac82540035f171dc80c6a21371e7

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In Astronomy and Astrophysics

1. A. Riess
2. A. Filippenko
3. G. Efstathiou
4. S. Jha
5. N. Smith
6. W. Freedman
7. J. Silverman
8. Weidong Li

In Instrumentation

1. A. Riess
2. G. Efstathiou
3. A. Filippenko
4. J. Silverman
5. W. Freedman
6. Weidong Li
7. S. Jha
8. Ryan Chornock

Citations in the corpus

• EXTRAGALACTIC CHEMICAL ABUNDANCES: DO H ii REGIONS AND YOUNG STARS TELL THE SAME STORY? THE CASE OF THE SPIRAL GALAXY NGC 300 (2009, background): “…where the metal content of the young stellar populations has been derived from alternative tracers, including Cepheid variables (Luck et al. 2003; Romaniello et al. 2008) and B stars (Rolleston et al. 2000; Trundle et al. 2007), H II regions often represent the only source of presentday…”
• The Hubble Constant (2010, background): “For a comparison with recent theoretical studies we refer the interested readers to papers by Sandage, Bell & Tripicco (1999), Bono et al. (2008), Caputo (2008) and Romaniello et al. (2008, 2009).”
• A 2.4% DETERMINATION OF THE LOCAL VALUE OF THE HUBBLE CONSTANT (2016, methodology): “The mean metallicity of the LMC Cepheids is taken from their spectra by Romaniello et al. (2008) to be [ ] = -”
• Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics beyond ΛCDM (2019, methodology): “…all LMC Cepheids, we assume a mean [Fe/H]=−0.30 dex, which is chosen to be between the mean of −0.33 dex from 22 objects observed spectroscopically by Romaniello et al. (2008) and −0.27 dex, which is the mean of the photometric metallicity map of Choudhury et al. (2016) at the positions of the…”
• CARNEGIE HUBBLE PROGRAM: A MID-INFRARED CALIBRATION OF THE HUBBLE CONSTANT (2012, methodology): “…tests is discussed in F11, where the deviations of individual 3.6 μm LMC Cepheid magnitudes from the PL relation, as a function of spectroscopic [Fe/H] metal abundances (from Romaniello et al. 2008), exhibit only a very shallow (and statistically insignificant) slope of −0.09 ± 0.29 mag dex−1.”
• H 0 revisited (2013, background): “…dependence of the P-L relation at near-infrared wavelengths, however, both the variation of the metallicity dependence with waveband reported by Freedman and Madore (2011; see also Romaniello et al., 2008) and their error estimates should be treated with caution. c© 0000 RAS, MNRAS 000, 000–000”
• A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km s−1 Mpc−1 Uncertainty from the Hubble Space Telescope and the SH0ES Team (2021, methodology): “We take the mean SMC Cepheid metallicity to be Δ[Fe/ H]=−0.41 dex relative to the LMC or [O/H] =−0.70 dex (Romaniello et al. 2021, 2008) ([Fe/H]=−0.76).”
• On the fine structure of the Cepheid metallicity gradient in the Galactic thin disk (2014, methodology): “…et al. (2008) 0.95 Karczmarek et al. (2012) HV 1023 26.6073 -0.28 Romaniello et al. (2008) 0.87 Martin & Warren (1979) HV 12452 8.7297 -0.36 Romaniello et al. (2008) 0.82 Soszynski et al. (2008); Soszyñski et al. (2010) HV 12700 8.1470 -0.36 Romaniello et al. (2008) 0.56 Martin & Warren…”
• Scaled solar tracks and isochrones in a large region of the Z-Y plane. II. From 2.5 to 20 solar masses (2009, methodology): “In Figs 12, 13, and 14 we checked whether our models can reproduce the lower boundaries of the instability strip compatibly with the dispersion in Z found by Romaniello et al (2008) for SMC, LMC, and MW respectively.”
• New Parallaxes of Galactic Cepheids from Spatially Scanning the Hubble Space Telescope: Implications for the Hubble Constant (2018, methodology): “The LMC is a dwarf galaxy where the environment is quite different from the large spiral hosts used to calibrate SNeIa with Cepheids; its Cepheids are more metal-poor by 0.3–0.4 dex (Romaniello et al. 2008).”
• A 3% SOLUTION: DETERMINATION OF THE HUBBLE CONSTANT WITH THE HUBBLE SPACE TELESCOPE AND WIDE FIELD CAMERA 3 (2011, result): “While the abundances of MW Cepheids are not measured the same way (i.e., they are based on stellar absorption lines rather than on nearby ionized gas), they have been directly measured to be ∼0.3 dex higher than those of LMC Cepheids (Andrievsky et al. 2002; Romaniello et al. 2008).”