Calibration of the Extragalactic Distance Scale
By BARRY F. MADORE1, WENDY L. FREEDMAN21NASA/IPAC Extragalactic Database, Infrared Processing & Analysis Center, California Institute of Technology, Jet Propulsion Laboratory, Pasadena, CA 91125, USA 2Observatories, Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena CA 91101, USA
The calibration and use of Cepheids as primary distance indicators is reviewed in the context of the extragalactic distance scale. Comparison is made with the independently calibrated Population II distance scale and found to be consistent at the 10% level. The combined use of ground-based facilities and the Hubble Space Telescope now allow for the application of the Cepheid Period-Luminosity relation out to distances in excess of 20 Mpc. Calibration of secondary distance indicators and the direct determination of distances to galaxies in the field as well as in the Virgo and Fornax clusters allows for multiple paths to the determination of the absolute rate of the expansion of the Universe parameterized by the Hubble constant. At this point in the reduction and analysis of Key Project galaxiesH0 = 72km/sec/Mpc ± 2 (random) ± 12 [systematic] .
INTRODUCTION TO THE LECTURES
CEPHEIDS
BRIEF
SUMMARY OF THE OBSERVED PROPERTIES OF CEPHEID VARIABLES
SIMPLE
PHYSICAL CONSIDERATIONS
OBSERVATIONAL CONSIDERATIONS
General Issues
Reddening
Metallicity Sensitivity of the PL Relation
ADVANCES DRIVEN BY NEW TECHNOLOGY
Application of Near-Infrared Techniques
CCDs
and MULTIWAVELENGTH COVERAGE
OBTAINING ACCURATE CEPHEID DISTANCES
LOCAL
GROUP GALAXIES
The Magellanic Clouds
IC
1613
NGC 6822
M33
M31
BEYOND
THE LOCAL GROUP
NGC 2403
M81
M101
NGC 300
NGC 247 and 7793
WLM
IC 10
NGC 3109
Pegasus = DDO 216
Leo A = DDO 069
GRB = DDO 155
Sextans A and Sextans B
NGC 2366 = DDO 042
M83 (= NGC 5236) , IC 5152, and the
Phoenix Dwarf
The Centaurus Group
THE HUBBLE CONSTANT
THE FUTURE
CONTRASTING ASPECTS OF THE PL and PLC
A REDDENING-FREE FORMULATION OF THE PL RELATION
COMMENTS ON REDDENING DETERMINATIONS
COMPARISONS WITH OTHER DISTANCE INDICATORS
THE KEY PROJECT
Goals
First Results
OTHER GROUND-BASED WORK
Galactic Cluster and LMC Calibration
Recent Ground-Based Searches for Cepheids
HELIUM CORE FLASH AND THE TIP OF THE RED
GIANT BRANCH AS A PRIMARY DISTANCE INDICATOR
INTRODUCTION
THE IDEAL DISTANCE INDICATOR
SOME
HISTORY CONCERNING THE RED GIANT BRANCH
CONCERNS AND TECHNICAL ISSUES
Detecting the Tip
Asymptotic Giant Branch Stars
Red Supergiants
High-Metallicity Populations
Crowding
Sufficient Signal
Background Galaxies and Quasars
Cosmic Rays
RR Lyrae Distance Scale
AN
OVERVIEW OF THE THEORETICAL UNDERPINNINGS: CORE HELIUM IGNITION
RECENT APPLICATIONS OF THE TRGB METHOD
Ground-based Studies: The Local Group
HST Applications: Inside 10 Mpc
THE SCORECARD
CONCLUSIONS
IMPLICATIONS OF THE HIPPARCOS OBSERVATIONS
OF GALACTIC CEPHEIDS
INTRODUCTION
COMPARISON WITH V-BAND PERIOD-LUMINOSITY RELATIONS
MULTIWAVELENGTH PERIOD-LUMINOSITY RELATIONS
SUMMARY OF HIPPARCOS RESULTS
IMPLICATIONS OF A CEPHEID DISTANCE TO THE
FORNAX CLUSTER
INTRODUCTION
NGC 1365 AND THE FORNAX CLUSTER
HST OBSERVATIONS
CEPHEIDS IN NGC 1365
THE HUBBLE CONSTANT
THE HUBBLE CONSTANT AT FORNAX
UNCERTAINTIES IN THE FORNAX CLUSTER
DISTANCE AND VELOCITY
THE NEARBY FLOW FIELD
BEYOND FORNAX: THE TULLY-FISHER RELATION
BEYOND FORNAX: OTHER RELATIVE DISTANCE
DETERMINATIONS
BEYOND FORNAX: TYPE IA SUPERNOVAE
COSMOLOGICAL IMPLICATIONS
CONCLUSIONS
REFERENCES
This page is maintained by Cren Frayer
Last modified: 20-Jan-98.