Pith Number

pith:DLEI7MC3

pith:2026:DLEI7MC35TLFCHPUYJIJLXTQ7D

not attested not anchored not stored refs resolved

Large Interstellar Polarisation Survey. III. Observational constraints on the structure of grains

Lapo Fanciullo, Ralf Siebenmorgen, Stefano Bagnulo, Thomas Vannieuwenhuyse, Vincent Guillet

Interstellar dust grains are prolate with axial ratios of two and 10% porosity, achieving high alignment to reproduce observed reddening and polarisation spectra.

arxiv:2604.06986 v1 · 2026-04-08 · astro-ph.GA

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\usepackage{pith}
\pithnumber{DLEI7MC35TLFCHPUYJIJLXTQ7D}

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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

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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

The diversity of reddening and polarisation spectra is well reproduced by prolate grains with typical axial ratios of two, a porosity of 10%, and high alignment efficiencies. Such efficiencies can be achieved with radiative torque alignment theory (RAT), but not with imperfect Davis-Greenstein (IDG) alignment, except when adjusting the magnetic-field orientation to maximise the polarisation. Micrometre-sized dust contributes wavelength-independent grey extinction in the optical, accounts for about one-third of the visual extinction, and carries one-third of the dust mass.

C2weakest assumption

That varying axial ratios, porosities, sizes, element abundances, and alignment efficiencies within a three-component model is sufficient to capture the true structure and physics of interstellar grains without significant overfitting or missing components, and that the far-UV selected sample of 96 sightlines is representative without selection biases affecting the derived parameters.

C3one line summary

A three-component interstellar dust model with nanoparticles, amorphous grains, and micrometre-sized agglomerates using prolate shapes (axial ratio ~2), 10% porosity, and high alignment efficiency reproduces reddening and polarization spectra, with the large grains contributing one-third of visual 1

References

3 extracted · 3 resolved · 0 Pith anchors

[1] Allamandola, L. J., Tielens, A. G. G. M., & Barker, J. R. 1989, ApJS, 71, 733 Andersson, B.-G., Karoly, J., Bastien, P., et al. 2024, ApJ, 963, 76 Andersson, B.-G., Lazarian, A., & Vaillancourt, J. E. 1989 · doi:10.5281/zenodo.14624100

[2] aa55848-25 Table A.1.Stars with derived Planck, reddening, FORS, and Serkowski fit parameters 2019

[3] (2017), and S14 to Siebenmorgen et al 2017

Formal links

2 machine-checked theorem links

Receipt and verification

First computed	2026-05-27T14:06:43.348631Z
Builder	pith-number-builder-2026-05-17-v1
Signature	Pith Ed25519 (`pith-v1-2026-05`) · public key
Schema	pith-number/v1.0

Canonical hash

1ac88fb05becd6511df4c25095de70f8ea755bfc4ffc59f42326977b68604d54

Aliases

arxiv: 2604.06986 · arxiv_version: 2604.06986v1 · doi: 10.48550/arxiv.2604.06986 · pith_short_12: DLEI7MC35TLF · pith_short_16: DLEI7MC35TLFCHPU · pith_short_8: DLEI7MC3

Agent API

Resolver JSON Graph JSON Events JSON Schema Signing key

Verify this Pith Number yourself

curl -sH 'Accept: application/ld+json' https://pith.science/pith/DLEI7MC35TLFCHPUYJIJLXTQ7D \
  | 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: 1ac88fb05becd6511df4c25095de70f8ea755bfc4ffc59f42326977b68604d54

Canonical record JSON

{
  "metadata": {
    "abstract_canon_sha256": "8ed6bb5cd95bb3fcac5c679466ae4d3d2162b1447397205c7d1e25b912fe964b",
    "cross_cats_sorted": [],
    "license": "http://creativecommons.org/licenses/by-sa/4.0/",
    "primary_cat": "astro-ph.GA",
    "submitted_at": "2026-04-08T12:00:54Z",
    "title_canon_sha256": "6093e0d02ea864fb944459166f96749edb9f1f934fe0dd54c5cb62dea4799404"
  },
  "schema_version": "1.0",
  "source": {
    "id": "2604.06986",
    "kind": "arxiv",
    "version": 1
  }
}