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Has Blending Compromised Cepheid-based Determinations of the Extragalactic Distance Scale?
The Astrophysical Journal
|January 21, 2000
Summary
Stellar profile blending does not appear to significantly impact galaxy distance measurements. This study found no evidence that the Hubble Space Telescope Key Project or Type Ia Supernova Calibration Team underestimated galaxy distances due to blending effects.
Area of Science:
- Astronomy
- Cosmology
- Astrophysics
Background:
- The accuracy of extragalactic distance scales is crucial for cosmological studies.
- Potential systematic errors in distance measurements, such as stellar profile blending, require careful investigation.
Purpose of the Study:
- To evaluate the hypothesis that stellar profile blending systematically underestimates galaxy distances measured by the Hubble Space Telescope Key Project and the Type Ia Supernova Calibration Team.
- To assess the impact of blending on Cepheid-based extragalactic distance scales.
Main Methods:
- Analyzing trends in Type Ia supernova-corrected peak luminosity and Tully-Fisher residuals with increasing distance.
- Comparing distance moduli derived from Planetary Camera and Wide Field Camera observations within galaxies.
- Adopting a functional form for blending influence consistent with established models.
Main Results:
- No systematic trend was observed in Type Ia supernova-corrected peak luminosity or Tully-Fisher residuals with increasing calibrator distance.
- No significant differential offset was found between distance moduli from different camera types within the same galaxy.
- The data did not support the expected correlation between distance and blending effects predicted by existing models.
Conclusions:
- The influence of stellar profile blending on the Cepheid-based extragalactic distance scale appears to be negligible.
- The accuracy of current extragalactic distance measurements is not severely compromised by the neglect of blending effects.