Pith Number

pith:GKB2N2V3

pith:2026:GKB2N2V3CWFIBO7AVYZURWDYWI

not attested not anchored not stored refs pending

Tracing the kinematic perturbations of the Milky Way spiral arms with APOGEE DR17 and Gaia DR3

Hao Tian, Iulia T. Simion, Shuting Fan, Xi-Can Tang, Zhijian Luo, Zhi Li, Zi-Qi Li

A revised model including both sine and cosine radial-velocity terms reproduces Milky Way stellar streaming motions to within 2 percent, constraining spiral pitch angle to about 10 degrees.

arxiv:2605.10092 v2 · 2026-05-11 · astro-ph.GA

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\pithnumber{GKB2N2V3CWFIBO7AVYZURWDYWI}

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Record completeness

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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 revised model reproduces the phase and amplitude of the mock radial-velocity field to the ~2% level, substantially improving upon earlier V_R,sin-only formulations. Applied to the observational data, it yields a robust pitch angle of p ≃ 10° and a local surface density contrast of ξ ≃ 5--18% at the solar radius. The observed kinematics constrain the spiral pattern speed to Ω_p ≈ 10--20 km s^{-1} kpc^{-1}.

C2weakest assumption

The assumption that the observed velocity field is dominated by the steady-state response to a two-armed logarithmic spiral potential, with resonances properly accounted for and no major contributions from other non-axisymmetric perturbations or time-dependent effects.

C3one line summary

A revised steady-state radial-velocity response model with both V_R,sin and V_R,cos terms constrains the Milky Way's two-armed spiral to a pitch angle of ~10° and local density contrast of 5-18% at the solar radius.

Receipt and verification

First computed	2026-06-19T16:12:54.819990Z
Builder	pith-number-builder-2026-05-17-v1
Signature	Pith Ed25519 (`pith-v1-2026-05`) · public key
Schema	pith-number/v1.0

Canonical hash

3283a6eabb158a80bbe0ae3348d878b22ac293bb6ba1c23991ad2a4ca66f3b7f

Aliases

arxiv: 2605.10092 · arxiv_version: 2605.10092v2 · doi: 10.48550/arxiv.2605.10092 · pith_short_12: GKB2N2V3CWFI · pith_short_16: GKB2N2V3CWFIBO7A · pith_short_8: GKB2N2V3

Agent API

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Verify this Pith Number yourself

curl -sH 'Accept: application/ld+json' https://pith.science/pith/GKB2N2V3CWFIBO7AVYZURWDYWI \
  | 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: 3283a6eabb158a80bbe0ae3348d878b22ac293bb6ba1c23991ad2a4ca66f3b7f

Canonical record JSON

{
  "metadata": {
    "abstract_canon_sha256": "b5ec5412d71c8cf3fb7e60d976a297bc8bd7fe7c5c704970e491a1940739a7af",
    "cross_cats_sorted": [],
    "license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
    "primary_cat": "astro-ph.GA",
    "submitted_at": "2026-05-11T07:10:42Z",
    "title_canon_sha256": "50bd27bd15cf663ef90b412a54fc0c665ef633c243da2fbd93ec7be64619bb25"
  },
  "schema_version": "1.0",
  "source": {
    "id": "2605.10092",
    "kind": "arxiv",
    "version": 2
  }
}