A Survey for New Members of Taurus from Stellar to Planetary Masses

K. Luhman; T. Esplin

arxiv: 1907.00055 · v1 · pith:KZ2LTO56new · submitted 2019-06-28 · 🌌 astro-ph.SR · astro-ph.EP· astro-ph.GA

A Survey for New Members of Taurus from Stellar to Planetary Masses

T. Esplin , K. Luhman This is my paper

Pith reviewed 2026-05-25 12:57 UTC · model grok-4.3

classification 🌌 astro-ph.SR astro-ph.EPastro-ph.GA

keywords membersknownmassestauruscensusshouldstellarsurvey

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The pith

A survey adds 79 new confirmed members to Taurus from stellar to planetary masses using photometry, astrometry, and spectroscopy, doubling the count at spectral types M9 and later while updating disk fractions.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

Taurus is a nearby cloud where stars are being born. The team searched large sky images in visible and infrared light for objects whose colors and movements suggested they were young and part of the region. They then obtained spectra to measure temperatures and confirm membership for 161 candidates. This added many new faint objects, including the faintest known member, which models suggest has a mass between 3 and 10 times Jupiter's. They also checked infrared data from Spitzer and WISE to see which new members show extra light from surrounding disks of dust and gas. The result is a larger, more complete list of Taurus members and revised estimates of how often disks are present at different masses.

Core claim

Our updated census of Taurus now contains 519 known members. ... Our survey has doubled the number of known members at >= M9 and has uncovered the faintest known member in M_K, which should have a mass of ~3-10 M_Jup for ages of 1-10 Myr. The updated disk fraction for Taurus is ~0.7 at <= M3.5 and ~0.4 at >M3.5.

Load-bearing premise

The assumption that theoretical evolutionary models accurately map observed magnitudes and spectral types to masses for ages of 1-10 Myr, especially below the hydrogen-burning limit where model uncertainties are largest.

read the original abstract

We present a large sample of new members of the Taurus star-forming region that extend from stellar to planetary masses. To identify candidate members at substellar masses, we have used color-magnitude diagrams and proper motions measured with several wide-field optical and infrared (IR) surveys. At stellar masses, we have considered the candidate members that were found in a recent analysis of high-precision astrometry from the Gaia mission. Using new and archival spectra, we have measured spectral types and assessed membership for these 161 candidates, 79 of which are classified as new members. Our updated census of Taurus now contains 519 known members. According to Gaia data, this census should be nearly complete for spectral types earlier than M6-M7 at A_J<1. For a large field encompassing ~72% of the known members, the census should be complete for K<15.7 at A_J<1.5, which corresponds to ~5-13 M_Jup for ages of 1-10 Myr based on theoretical evolutionary models. Our survey has doubled the number of known members at greater or equal to M9 and has uncovered the faintest known member in M_K, which should have a mass of ~3-10 M_Jup for ages of 1-10 Myr. We have used mid-IR photometry from the Spitzer Space Telescope and the Wide-field Infrared Survey Explorer to determine whether the new members exhibit excess emission that would indicate the presence of circumstellar disks. The updated disk fraction for Taurus is ~0.7 at less than or equal to M3.5 and ~0.4 at >M3.5.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

This updates the Taurus census with 79 new spectroscopically confirmed members and revised disk fractions, but the planetary-mass claims for the faintest objects depend on uncertain evolutionary models.

read the letter

The main thing here is a larger catalog of Taurus members. They add 79 new ones confirmed by spectra, bringing the total to 519, double the count at M9 and later, and report updated disk fractions of about 0.7 below M3.5 and 0.4 above it. The faintest new member is presented as likely 3-10 Jupiter masses at 1-10 Myr ages. Gaia data improves the proper-motion selection for the stellar-mass candidates, and they combine that with color-magnitude and proper-motion cuts from other surveys for the substellar ones. Membership rests on spectra plus the usual photometric and astrometric checks, with explicit statements on completeness for types earlier than M6-M7 and for K less than 15.7 in a large field. Disk excesses come straight from Spitzer and WISE photometry. Those parts are direct and do not require extra assumptions. The soft spot is the mass scale. The quoted range for the faintest object and the completeness limit around 5-13 Jupiter masses both come from theoretical evolutionary models, which carry larger systematic errors at young ages and below the hydrogen-burning limit. The paper already gives a broad range, but the planetary-mass framing inherits that uncertainty. The raw member counts and disk fractions do not. This is for people who track the initial mass function or disk statistics in nearby star-forming regions and need an updated member list. It is the kind of incremental catalog work that gets cited for the numbers it adds. It deserves peer review because the new observations are concrete and the completeness discussion is useful, even if the lowest-mass masses need the usual model caveats.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The paper relies on external evolutionary models and standard membership criteria but introduces no new free parameters, axioms, or invented entities beyond those in the cited literature.

axioms (1)

domain assumption Taurus members have ages between 1 and 10 Myr
Used to convert observed magnitudes to mass estimates via theoretical models.

pith-pipeline@v0.9.0 · 5834 in / 1226 out tokens · 33957 ms · 2026-05-25T12:57:27.915342+00:00 · methodology

discussion (0)

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

IndisputableMonolith/Cost/FunctionalEquation.lean washburn_uniqueness_aczel unclear

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unclear
Relation between the paper passage and the cited Recognition theorem.

Our updated census of Taurus now contains 519 known members... completeness for K<15.7 at A_J<1.5, which corresponds to ~5-13 M_Jup... faintest known member... mass of ~3-10 M_Jup... based on theoretical evolutionary models (Burrows et al. 1997; Chabrier et al. 2000).
IndisputableMonolith/Foundation/RealityFromDistinction.lean reality_from_one_distinction unclear

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unclear
Relation between the paper passage and the cited Recognition theorem.

We have used mid-IR photometry... to determine whether the new members exhibit excess emission... disk fraction... ~0.7 at <=M3.5 and ~0.4 at >M3.5.

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