The Cepheid PL-Z
Abstract
We are proposing to empirically calibrate the metallicity sensitivity of the Cepheid Period-Luminosity relation at the highest metallicity range so far observed in nearby galaxies. To do this we will obtain the I-band Population II Tip of the Red Giant Branch {TRGB} distances to two galaxies, NGC 3627 and NGC 3368, both of which have comparable {Cepheid} distances of 11 Mpc and have almost identical {very high} metallicities of 12 + log[O/H] = +9.3. At present, observers have extremely divergent views on the magnitude of the metallicity effect on the Cepheid zero point, and theorists cannot even agee upon the sign of the effect.
- Publication:
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HST Proposal
- Pub Date:
- July 2004
- Bibcode:
- 2004hst..prop10433M