The Cepheid Extragalactic Distance Scale: Past, Present and Future

Barry F. Madore; Wendy L. Freedman

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The Cepheid Extragalactic Distance Scale: Past, Present and Future

Wendy L. Freedman, Barry F. Madore

Cosmology and Nongalactic Astrophysics · Submitted 4 Aug 2023

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim Early JWST data for the galaxy, NGC 7250 show a decrease in scatter in the Cepheid Leavitt law by a factor of two relative to existing HST data and demonstrate that crowding/blending effects are a significant issue in a galaxy as close as 20 Mpc.

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What the abstract itself states, as probabilities: claims first 0.04 · states limitation 0.53 · human participants 0.02 · controlled comparison 0.31 · randomized assignment 0.01 · states quantitative result 0.96 · compares with prior results 0.91 · mentions code or data availability 0.02.

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arXiv listing abstract v1. Results and the main claim are underlined; show every role.

Cepheids have been the cornerstone of the extragalactic distance scale for a century. With high-quality data, these luminous supergiants exhibit a small dispersion in their Leavitt (period-luminosity) relation, particularly at longer wavelengths, and few methods rival the precision possible with Cepheid distances. In these proceedings, we present an overview of major observational programs pertaining to the Cepheid extragalactic distance scale, its progress and remaining challenges. In addition, we present preliminary new results on Cepheids from the James Webb Space Telescope (JWST). The launch of JWST has opened a new chapter in the measurement of extragalactic distances and the Hubble constant. JWST offers a resolution three times that of the Hubble Space Telescope (HST) with nearly 10 times the sensitivity. It has been suggested that the discrepancy in the value of the Hubble constant based on Cepheids compared to that inferred from measurements of the cosmic microwave background requires new and additional physics beyond the standard cosmological model. JWST observations will be critical in reducing remaining systematics in the Cepheid measurements and for confirming if new physics is indeed required. Early JWST data for the galaxy, NGC 7250 show a decrease in scatter in the Cepheid Leavitt law by a factor of two relative to existing HST data and demonstrate that crowding/blending effects are a significant issue in a galaxy as close as 20 Mpc.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	Cepheids have been the cornerstone of the extragalactic distance scale for a century.	background 1.00	0.04	0.04	asserted 1.00
s1	With high-quality data, these luminous supergiants exhibit a small dispersion in their Leavitt (period-luminosity) relation, particularly at longer wavelengths, and few methods rival the precision possible with Cepheid distances.	background 1.00	0.09	0.05	asserted 0.98
s2	In these proceedings, we present an overview of major observational programs pertaining to the Cepheid extragalactic distance scale, its progress and remaining challenges.	contribution 0.99	0.54	0.06	asserted 0.85
s3	In addition, we present preliminary new results on Cepheids from the James Webb Space Telescope (JWST).	contribution 1.00	0.89	0.05	asserted 0.98
s4	The launch of JWST has opened a new chapter in the measurement of extragalactic distances and the Hubble constant.	background 0.86	0.07	0.10	asserted 1.00
s5	JWST offers a resolution three times that of the Hubble Space Telescope (HST) with nearly 10 times the sensitivity.	background 0.76	0.08	0.04	asserted 1.00
s6	It has been suggested that the discrepancy in the value of the Hubble constant based on Cepheids compared to that inferred from measurements of the cosmic microwave background requires new and additional physics beyond the standard cosmological model.	background 0.98	0.05	0.07	hedged possibility 0.97
s7	JWST observations will be critical in reducing remaining systematics in the Cepheid measurements and for confirming if new physics is indeed required.	future work 0.79	0.08	0.19	asserted 0.71
s8	Early JWST data for the galaxy, NGC 7250 show a decrease in scatter in the Cepheid Leavitt law by a factor of two relative to existing HST data and demonstrate that crowding/blending effects are a significant issue in a galaxy as close as 20 Mpc.	result 1.00	0.87	0.24	asserted 1.00

What kind of paper the classifier reports this is: review 0.78 · evidence from observation or experiment 0.81.

What was examined, and what was not

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arXiv listing abstract v1

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full text
figures and tables
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T body sentences
C citations
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Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

The paper

Original abstract

Cepheids have been the cornerstone of the extragalactic distance scale for a century. With high-quality data, these luminous supergiants exhibit a small dispersion in their Leavitt (period-luminosity) relation, particularly at longer wavelengths, and few methods rival the precision possible with Cepheid distances. In these proceedings, we present an overview of major observational programs pertaining to the Cepheid extragalactic distance scale, its progress and remaining challenges. In addition, we present preliminary new results on Cepheids from the James Webb Space Telescope (JWST). The launch of JWST has opened a new chapter in the measurement of extragalactic distances and the Hubble constant. JWST offers a resolution three times that of the Hubble Space Telescope (HST) with nearly 10 times the sensitivity. It has been suggested that the discrepancy in the value of the Hubble constant based on Cepheids compared to that inferred from measurements of the cosmic microwave background requires new and additional physics beyond the standard cosmological model. JWST observations will be critical in reducing remaining systematics in the Cepheid measurements and for confirming if new physics is indeed required. Early JWST data for the galaxy, NGC 7250 show a decrease in scatter in the Cepheid Leavitt law by a factor of two relative to existing HST data and demonstrate that crowding/blending effects are a significant issue in a galaxy as close as 20 Mpc.

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References

Forward citations

Cited by 5 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

The SRG/eROSITA All-Sky Survey: Early dark energy and Hubble constant from the cluster mass function
astro-ph.CO 2026-09 conditional novelty 7.0 of 10

Cluster number counts from eRASS1 provide the first cluster-based constraint on early dark energy, with a joint analysis yielding f_EDE = 0.10^{+0.04}_{-0.03} and H0 = 71.4 ± 1.4 km/s/Mpc at 3.2 sigma significance.
Status Report on the Chicago-Carnegie Hubble Program (CCHP): Measurement of the Hubble Constant Using the Hubble and James Webb Space Telescopes
astro-ph.CO 2024-08 conditional novelty 6.0 of 10

Tip-of-the-red-giant-branch and JAGB distances measured with JWST yield H0 = 68.8 to 70.4 km/s/Mpc, consistent with Planck and DESI and in only mild tension with the Cepheid value of 73.
Theoretical RR Lyrae Instability Strip from MESA-RSP Pulsation models and updated BaSTI Evolutionary Tracks
astro-ph.SR 2026-09 conditional novelty 5.0 of 10

Updated BaSTI tracks plus mesa-rsp linear pulsation models reproduce earlier RR Lyrae instability strips while showing the strip edges and period-luminosity relations depend jointly on mode, metallicity, and convectio...
The independence of the mid-infrared RR Lyrae Period-Luminosity relation from metallicity from a study of three globular clusters in the Large Magellanic Cloud
astro-ph.SR 2026-09 accept novelty 5.0 of 10

The mid-infrared Period-Luminosity relation for RR Lyrae RRab stars shows no statistically significant dependence on metallicity, based on Spitzer observations of three LMC clusters.
The potential broader complex linked to the key Cepheid SV Vul
astro-ph.SR 2026-07 conditional novelty 5.0 of 10

SV Vul and its host cluster Alicante 13 lie at 2.30 ± 0.13 kpc and may share a common origin with the nearby cluster Liu-Pang 1738.

How the literature uses it

9 arXiv papers cite this in 14 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 8 sentences without a confident label

Contests it 1 paper

It is important to note that the optical measurements are not `random-phase' as claimed in the previous contribution [ref] ; they are at known phases due determined from the simultanoues white-light light curves and, thus, are used to measure the magnitudes at mean phase.

The Local Value of H$_0$ · SNe Ia calibrations · contest 0.80

Uses its data or values 1 paper

In particular, the inferred value of $H_0$ in the standard flat $Λ$CDM cosmological model using cosmic microwave background (CMB) measurements from the Planck DR3 [ref] , i.e. $H_0 = 67.36 ±0.54 km s^-1 Mpc^-1$, deviates by $5σ$ from the value obtained through the distance ladder calibration of type Ia supernovae (SN Ia) from the Pantheon+ compilation [ref] by the S$H_0$ES collaboration [ref] , i.e. $H_0 = 73.0 ±1.0 km s^-1 Mpc^-1$ (see also Refs. [ref] for discussions).

Probing Early Modification of Gravity with Planck, ACT and SPT · Introduction · 0.90

Compares with it 1 paper

The optimal values of $σ_8$ in our DDE analysis is still in $4.5σ$ tension with Planck, though the $H_0$ is consistent with Planck and not with the value implied by the Cepheid-calibrated distance ladder [ref] (though in better agreement with [ref] ).

Suppression without Thawing: Constraining Structure Formation and Dark Energy with Galaxy Clustering · Introduction · 0.93

Cites it as background 3 papers

The most common such objects are Cepheid stars—which obey a linear relation between their distance-independent pulsation period and distance-dependent luminosity (for reviews see [ref] )—and the Tip-of-the-Red-Giant-Branch (TRGB) feature of the colour–magnitude diagram, which has a fixed luminosity arising from the

Consistencies and inconsistencies in redshift-independent distances · Introduction · 1.00
A recent review of Cepheids as distance indicators is given by Freedman & Madore [ref] .

Progress in Direct Measurements of the Hubble Constant · Progress Since the Key Project: The Cepheid Distance Scale: 2001-2023 · 1.00
[ref] provide an additional overview of the current situation.

On dataset tensions and signatures of new cosmological physics · The Hubble tension · 0.97

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