Pith Number

pith:IKCYW3M4

pith:2026:IKCYW3M4EPMVZRJ5XP3USM3C3L

not attested not anchored not stored refs resolved

The Panchromatic Hubble Andromeda Southern Treasury (PHAST). II. The Spatially Resolved Recent Star Formation History in M31

Adam Smercina, Andrew Dolphin, Benjamin F. Williams, Daniel R. Weisz, Debby Tran, Ekta Patel, Eric F. Bell, Eric W. Koch, Francois Hammer, Julianne J. Dalcanton, Julia Roman-Duval, Kameron Goold, Karoline M. Gilbert, Kristen. B. W. McQuinn, L. Clifton Johnson, Margaret Lazzarini, Meredith J. Durbin, Puragra Guhathakurta, Stefany L. Fabian Dub\'on, Tobin M. Wainer, Vaishnav V. Rao, Zhuo Chen

M31's star formation rate has declined globally with a pronounced drop in the last 40 million years.

arxiv:2605.12721 v1 · 2026-05-12 · astro-ph.GA

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\usepackage{pith}
\pithnumber{IKCYW3M4EPMVZRJ5XP3USM3C3L}

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Record completeness

1 Bitcoin timestamp

2 Internet Archive

3 Author claim open · sign in to claim

4 Citations open

5 Replications open

✓ Portable graph bundle live · download bundle · merged state

The bundle contains the canonical record plus signed events. A mirror can host it anywhere and recompute the same current state with the deterministic merge algorithm.

Claims

C1strongest claim

We find a clear global decline in the recent SFR, with a pronounced drop in the last ∼40 Myr that is most evident in the region closest to M32. Combining PHAST and PHAT measurements, we now cover two thirds of M31's star-forming disk with homogeneous SFHs... mean SFRs of 0.445 ±0.006 M⊙ yr−1 over the last 100 Myr and 0.285 ± 0.014 M⊙ yr−1 over the last 20 Myr.

C2weakest assumption

The CMD-fitting procedure using standard stellar population synthesis models recovers the true recent SFH without large systematic biases from crowding, variable extinction, or inaccuracies in the adopted isochrones and initial mass function for M31's stellar populations.

C3one line summary

PHAST data yield spatially resolved SFHs across M31's southern disk showing a global recent SFR decline driven by reduced ring activity, with mean rates of 0.445 and 0.285 solar masses per year over the last 100 and 20 Myr.

References

13 extracted · 13 resolved · 2 Pith anchors

[1] 2013, in Secular Evolution of Galaxies, 419, doi: 10.48550/arXiv.1208.2997 2025 · doi:10.48550/arxiv.1208.2997

[2] 2002, Monthly Notices of the Royal Astronomical Society, 332, 2002

[3] 2013, The Astrophysical Journal, 775, 76, aDS Bibcode: 2013ApJ...775...76D 2013 · doi:10.48550/arxiv.2403.19798

[4] http://adsabs.harvard.edu/abs/2010ApJ...724.1030G Gogarten, S. M., Dalcanton, J. J., Williams, B. F., et al. 2010, The Astrophysical Journal, 712, 858, aDS Bibcode: 2010ApJ...712..858G. https://ui.ads 2010 · doi:10.5281/zenodo.12522488

[5] 2009, The Astrophysical Journal, 703, 614, aDS Bibcode: 2009ApJ...703..614K 2009

Formal links

1 machine-checked theorem link

Receipt and verification

First computed	2026-05-18T03:09:49.394732Z
Builder	pith-number-builder-2026-05-17-v1
Signature	Pith Ed25519 (`pith-v1-2026-05`) · public key
Schema	pith-number/v1.0

Canonical hash

42858b6d9c23d95cc53dbbf7493362dae0cd38bcfbacc2809ad1d67acd132e6d

Aliases

arxiv: 2605.12721 · arxiv_version: 2605.12721v1 · doi: 10.48550/arxiv.2605.12721 · pith_short_12: IKCYW3M4EPMV · pith_short_16: IKCYW3M4EPMVZRJ5 · pith_short_8: IKCYW3M4

Agent API

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Verify this Pith Number yourself

curl -sH 'Accept: application/ld+json' https://pith.science/pith/IKCYW3M4EPMVZRJ5XP3USM3C3L \
  | jq -c '.canonical_record' \
  | python3 -c "import sys,json,hashlib; b=json.dumps(json.loads(sys.stdin.read()), sort_keys=True, separators=(',',':'), ensure_ascii=False).encode(); print(hashlib.sha256(b).hexdigest())"
# expect: 42858b6d9c23d95cc53dbbf7493362dae0cd38bcfbacc2809ad1d67acd132e6d

Canonical record JSON

{
  "metadata": {
    "abstract_canon_sha256": "358c8789468996573d580b521d2aedcd07c1c8b864b2d82d1d5cbce41c1f6c30",
    "cross_cats_sorted": [],
    "license": "http://creativecommons.org/licenses/by/4.0/",
    "primary_cat": "astro-ph.GA",
    "submitted_at": "2026-05-12T20:27:41Z",
    "title_canon_sha256": "0e092e802a1d5ee2b9a0ccd2ea80d99536dca090b61e5c67e682461fce09bac7"
  },
  "schema_version": "1.0",
  "source": {
    "id": "2605.12721",
    "kind": "arxiv",
    "version": 1
  }
}