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Abstract We present the firstgri-band period–luminosity (PL) and period–Wesenheit (PW) relations for the fundamental mode anomalous Cepheids. These PL and PW relations were derived from a combined sample of five anomalous Cepheids in globular cluster M92 and the Large Magellanic Cloud, both of which have distance accurate to ∼1% available from literature. Ourg-band PL relation is similar to theB-band PL relation as reported in previous study. We applied our PL and PW relations to anomalous Cepheids discovered in dwarf galaxy Crater II, and found a larger but consistent distance modulus than the recent measurements based on RR Lyrae. Our calibrations ofgri-band PL and PW relations, even though less precise due to small number of anomalous Cepheids, will be useful for distance measurements to dwarf galaxies.
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This content will become publicly available on April 1, 2026
The Legacy of Henrietta Leavitt: A Re-analysis of the First Cepheid Period–Luminosity Relation
Abstract Henrietta Swan Leavitt’s discovery of the relationship between the period and luminosity (hereafter the Leavitt Law) of 25 variable stars in the Small Magellanic Cloud, published in 1912, revolutionized cosmology. These variables, eventually identified as Cepheids, became the first known “standard candles” for measuring extragalactic distances and remain the gold standard for this task today. Leavitt measured light curves, periods, and minimum and maximum magnitudes from painstaking visual inspection of photographic plates. Her work paved the way for the first precise series of distance measurements that helped set the scale of the Universe, and later the discovery of its expansion by Edwin Hubble in 1929. Here, we re-analyze Leavitt’s first Period–Luminosity relation using observations of the same set of stars but with modern data and methods of Cepheid analysis. Using only data from Leavitt’s notebooks, we assess the quality of her light curves, measured periods, and the slope and scatter of her Period–Luminosity relations. We show that modern data and methods, for the same objects, reduce the scatter of the Period–Luminosity relation by a factor of two. We also find a bias brightward at the short period end, due to the nonlinearity of the plates and environmental crowding. Overall, Leavitt’s results are in excellent agreement with contemporary measurements, reinforcing the value of Cepheids in cosmology today, a testament to the enduring quality of her work.
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- Award ID(s):
- 2401770
- PAR ID:
- 10590928
- Publisher / Repository:
- IOP Science
- Date Published:
- Journal Name:
- Publications of the Astronomical Society of the Pacific
- Volume:
- 137
- Issue:
- 4
- ISSN:
- 0004-6280
- Page Range / eLocation ID:
- 044001
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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