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A Cepheid distance to NGC 4258

Eyal Maoz, Jeffrey A. Newman, Laura Ferrarese, P. B. Stetson, Stephen E. Zepf, Marc Davis et al. · 1999 · 0 citationsRead the paper

Distances measured using Cepheid variable stars have been essential for establishing the cosmological distance scale and the value of the Hubble constant. These stars have remained the primary extragalactic distance indicator since 1929 because of the small observed scatter in the relationship between their pulsation period and luminosity, their large numbers, which allow many independent measures of the distance to a galaxy, and the simplicity of the basic physics underlying their variability. Potential systematic uncertainties in the use of the LMC-calibrated Cepheid period-luminosity relation to determine distances using HST are estimated to be 8-10%. Here we describe the results of a search for Cepheids in the nearby galaxy NGC 4258, which has an independently determined geometric distance of 7.2 +/- 0.5 Mpc (Herrnstein et al. 1999). We obtain a Cepheid distance of 8.1 +/- 0.4 (excluding possible systematic errors affecting all HST Cepheid distances) Mpc; there is a 1.3 sigma difference between the two measurements. If the maser-based distance is adopted and other HST Cepheid distances are revised according to our results, the derived value of the Hubble constant would be increased by 12 +/- 9%, and the corresponding age of the Universe would decrease by the same factor.

What the full text shows

Tested in real conditions
  • Cepheid distance to NGC 4258 determined using DoPHOT photometry. — 8.1 +/- 0.4 Mpc (Excluding systematic errors affecting all HST Cepheid distances)
  • Comparison between Cepheid distance and independent maser-based geometric distance. — 1.3 sigma difference (Maser distance of 7.2 +/- 0.5 Mpc)
  • Potential impact on the Hubble constant if maser-based distance is adopted for recalibration. — 12% +/- 9% increase (Assuming maser distance is correct and other HST Cepheid distances are revised)
  • Potential impact on the age of the Universe if maser-based distance is adopted. — 12% +/- 9% decrease (Assuming maser distance is correct and other HST Cepheid distances are revised)
Setup
15 identified Cepheids in the galaxy NGC 4258.
How
Search for Cepheid variables using HST WFPC2 camera across 11 epochs with F555W and F814W filters. Point-spread-function fitting photometry was performed using DAOPHOT/ALLFRAME and DoPHOT software packages.
Limitations
Difficulty in obtaining accurate aperture corrections due to few bright, isolated stars in the field. · Uncertainties in the distance modulus to the LMC. · Potential effects of chemical composition differences between the LMC and target galaxies. · Uncertainty in the eccentricity of the circumnuclear disk for the maser distance measurement.

Summarized by Gemma 4 from the open-access full text · 9 Oct 2026. Read it