THE 2014 ALMA LONG BASELINE CAMPAIGN: FIRST RESULTS FROM HIGH ANGULAR RESOLUTION OBSERVATIONS TOWARD THE HL TAU REGION

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Science and technology studies

Consensus categories

none

Domain

Candidate signal: noneConsensus signal: none

Study design

Candidate signal: Not applicableConsensus signal: none

Genre

Candidate signal: EmpiricalConsensus signal: Empirical

Teacher disagreement score

0.559

Threshold uncertainty score

1.000

Validation status

machine_predicted_unvalidated · codex-gemma-dda1882f352a

Codex and Gemma teacher scores by category

Machine scores (provisional)

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Teacher spread

0.199 · how far apart the two teachers sit on this one work

Validation status

score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Abstract

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations from the 2014 Long Baseline Campaign in dust continuum and spectral line emission from the HL Tau region. The continuum images at wavelengths of 2.9, 1.3, and 0.87 mm have unprecedented angular resolutions of 0 075 (10 AU) to 0 025 (3.5 AU), revealing an astonishing level of detail in the circumstellar disk surrounding the young solar analog HL Tau, with a pattern of bright and dark rings observed at all wavelengths. By fitting ellipses to the most distinct rings, we measure precise values for the disk inclination ( ) and position angle We obtain a high-fidelity image of the 1.0 mm spectral index ( α ), which ranges from in the optically thick central peak and two brightest rings, increasing to 2.3–3.0 in the dark rings. The dark rings are not devoid of emission, and we estimate a grain emissivity index of 0.8 for the innermost dark ring and lower for subsequent dark rings, consistent with some degree of grain growth and evolution. Additional clues that the rings arise from planet formation include an increase in their central offsets with radius and the presence of numerous orbital resonances. At a resolution of 35 AU, we resolve the molecular component of the disk in HCO + (1-0) which exhibits a pattern over LSR velocities from 2–12 km s −1 consistent with Keplerian motion around a ∼1.3 star, although complicated by absorption at low blueshifted velocities. We also serendipitously detect and resolve the nearby protostars XZ Tau (A/B) and LkH α 358 at 2.9 mm.

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The record

Venue

The Astrophysical Journal Letters

Topic

Astrophysics and Star Formation Studies

Field

Physics and Astronomy

Canadian institutions

Herzberg Institute of Astrophysics

Funders

not available

Keywords

Spectral indexPosition anglePlanetRADIUSSpectral lineAngular diameterOrbital motionWavelengthAngular resolution (graph drawing)

Has abstract in OpenAlex

yes

API

/api/v1/works/W1920023268