Classical Cepheid variable stars are potentially the most accurate distance indicators available for the near-field (0.5 kpc - 10 Mpc). Their suitability as distance indicators arises from a number of factors including luminosity (MV = -2 to -7 mag), ease of detection through variability, precision, permanence, and understanding of the pulsation phenomenon. The classical (or Type I) Cepheids are young, disk objects and as such are only found in galaxies with recent star formation (primarily spiral or irregular galaxies).
There is a vast literature on Cepheid variables as distance indicators and a full historical review is beyond the scope of this paper. Fernie (1969) gives a thorough and entertaining discussion of the early years. Other useful reviews of Cepheids as distance indicators are found in Feast and Walker (1987), Freedman (1988a), Walker (1988), and Madore and Freedman (1991).
The advantages of modern detectors for Cepheid work are legion and a number of known extragalactic Cepheids have been re-observed with CCDs and IR arrays. However, few discovery surveys have made it into print at this writing. Rather than discuss such surveys on a case by case basis, we summarize the observational papers on extragalactic Cepheids in Table 1 (excluding LMC and SMC work). Future surveys are likely to be tied to specific calibration needs such as the luminosity-line width relations or supernovae.
The sequence of operations required to find and use Cepheids for estimating distances is the same for any region of the visible spectrum, and we describe this process in the next section. We then discuss the tradeoffs between optical and near-infrared photometry.
Galaxy | Reference | Detector | Comments | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Local Group | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
M31
| Hubble, 1929
| Gaposchkin, 1962 Baade and Swope, 1963 Baade and Swope, 1965 Welch et al., 1986 Freedman and Madore, 1990 [Metcalfe and Shanks, 1991] pg | pg pg pg InSb CCD CCD Discovery survey | Discovery survey, Field II Discovery survey, Field IV Discovery survey, Fields I, III Metallicity effects Corrections to standard sequence M33
| Hubble, 1926
| van den Bergh, Herbst, and Kowal, 1975 Sandage, 1983 Sandage and Carlson, 1983 Madore et al., 1985 [Christian and Schommer, 1987] Mould, 1987 Kinman, Mould, and Wood, 1987 Freedman, Wilson, and Madore, 1991 [Metcalfe and Shanks, 1991] pg | pg pg pg InSb CCD CCD pg CCD CCD Discovery survey | Discovery survey Discovery survey Discovery survey Corrections to standard sequence Single epoch Discovery survey, r, automated Corrections to standard sequence NGC 6822
| Hubble, 1925
| Kayser, 1967 McAlary et al., 1983 pg | pg InSb Discovery survey
| IC 1613
| Sandage, 1971
| McAlary, Madore, and Davis, 1984 Freedman, 1988b pg | InSb CCD Discovery survey
| Phoenix
| Caldwell and
Schommer, 1988
| CCD
| Discovery survey, progress report
| WLM
| Sandage and
Carlson 1985b
| pg
| Discovery survey
| M81 Group
| M81
| Freedman and
Madore, 1988
| Mould et al. CCD | CCD Discovery survey (HST Cycle I)
| NGC 2403
| Tammann and
Sandage, 1968
| McAlary and Madore, 1984 Freedman and Madore, 1988 [Metcalfe and Shanks, 1991] pg | InSb CCD CCD Discovery survey | Corrections to standard sequence Sculptor Group
| NGC 247
| Freedman et
al., 1988
| CCD
| Discovery survey, progress report
| NGC 253
| Freedman et
al., 1988
| CCD
| Discovery survey, progress report
| NGC 300
| Graham, 1984
| Madore et al., 1987 pg | InSb Discovery survey
| NGC 7793
| Freedman et
al., 1988
| CCD
| Discovery survey, progress report
| Other
| Sex A
| Sandage and
Carlson, 1982
| [Walker, 1987] pg | CCD Discovery survey | Corrections to standard sequence Sex B
| Sandage and
Carlson, 1985a
| pg
| Discovery survey
| NGC 3109
| Demers,
Kunkel, and Irwin, 1985
| Sandage and Carlson, 1988 Capacioli, Piotto, and Bresolin, 1992 pg | pg CCD Discovery survey, automated | Discovery survey IC 5152
| Caldwell and
Schommer, 1988
| CCD
| Discovery survey, progress report
| DDO 216
| Hoessel et al., 1990
| pg
| Discovery survey (aka Pegasus dwarf)
| Leo A
| Hoessel, Saha,
and Danielson, 1991
| pg
| Discovery survey
| NGC 5068
| Walker, 1990
| CCD
| In progress
| NGC 5128
| Walker, 1990
| CCD
| In progress
| NGC 5236
| Caldwell and
Scommer, 1990
| CCD
| In progress
| NGC 5408
| Walker, 1990
| CCD
| In progress
| 324-g24
| Walker, 1990
| CCD
| In progress
| 444-g84
| Walker, 1990
| CCD
| In progress
| 381-g20
| Walker, 1990
| CCD
| In progress
| IC 4182
| Sandage et al.
| CCD
| Discovery survey (HST Cycle I)
| M101
| Cook,
Aaronson, and Illingworth, 1986
| Cohen et al. CCD | CCD Discovery survey | In progress (Palomar Consortium) Virgo Cluster
| NGC 4571
| Pierce et al.
| CCD
| In progress
| NGC 4321
| Pierce et al.
| CCD
| In progress
| |