Hubble Space Telescope Astrometry in the Orion Nebula Cluster: Census of Low-mass Runaways

Platais, I.; Robberto, M.; Bellini, Andrea; Kozhurina-Platais, V.; Gennaro, Mario; Hillenbrand, Lynne A.; Mink, S. E. de; Soderblom, David R.

doi:10.3847/1538-3881/ab8d42

Cited by 20 publications

(20 citation statements)

References 39 publications

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“…The literature on runaway (and walkaway) stars from Villafranca O-023 reaches to the 1950s, as the prototype dynamical ejection that expelled AE Aur, µ Col, and ι Ori (Blaauw & Morgan 1954;Hoogerwerf et al 2000;Maíz Apellániz et al 2018b) took place there 2.5 Ma ago. Recent analyses have been carried out using Gaia DR2 (Schoettler et al 2020;Farias et al 2020) and HST (Platais et al 2020) data. We have searched the Gaia EDR3 astrometry and found five walkaway/runaway candidates.…”

Section: Villafranca O-023 = Orion Nebula Cluster = M42+m43 = Ngc 1976+1982mentioning

confidence: 99%

The Villafranca catalog of Galactic OB groups

Apellániz

Barbá

Aranda

et al. 2022

A&A

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Context. This is the second paper of a series on Galactic OB groups that uses astrometric and photometric data from Gaia and spectral classifications from the Galactic O-Star Spectroscopic Survey (GOSSS) and the Library of Libraries of Massive-star high-Resolution spectra (LiLiMaRlin). The previous paper was based on the second Gaia data release (DR2). Since then, the early third Gaia data release (EDR3) has appeared with new astrometry and photometry. Aims. The two aims of this paper are to revise the results for the sample from paper I using Gaia EDR3 data and to expand the sample of analyzed stellar groups to 26, from Villafranca O-001 to Villafranca O-026. Methods. We used GOSSS to select Galactic stellar groups with O stars and an updated version of the method in paper 0 of this series, combining Gaia EDR3 G + G BP + G RP photometry, positions, proper motions, and parallaxes to assign memberships and measure distances. We present 99 spectra from GOSSS and 32 from LiLiMaRlin for stars in the analyzed groups or in their foreground.Results. We derived distances to the 26 stellar groups with unprecedented precision and accuracy, with total (random plus systematic) uncertainties lower than 1% for distances within 1 kpc and of ∼3% around 3 kpc, which are values almost four times better than for Gaia DR2. We provide homogeneous spectral types for 110 stars and correct a number of errors in the literature, especially for objects in Villafranca O-023 (Orion nebula cluster). For each group, we discuss its membership and present possible runaway and walkaway stars. At least two of the studied groups, Villafranca O-O12 S in NGC 2467 and Villafranca O-014 NW in the North America nebula, are orphan clusters in which the most massive stars have been ejected by dynamical interactions, leaving objects with a capped mass function. The existence of such clusters has important consequences for the study of the initial mass function (IMF), the distribution of supernova explosions across the Galaxy, and the population and dynamics of isolated compact objects. We fit pre-main-sequence (PMS) isochrones to the color-magnitude diagrams (CMDs) of four clusters to derive ages of 2.0±0.5 Ma for Villafranca O-026 (σ Orionis cluster), 4±2 Ma for Villafranca O-016 (NGC 2264), 5.0±0.5 Ma for Villafranca O-021 (NGC 2362), and 8±2 Ma for Villafranca O-024 (γ Velorum cluster).

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Section: Villafranca O-023 = Orion Nebula Cluster = M42+m43 = Ngc 1976+1982mentioning

confidence: 99%

The Villafranca catalog of Galactic OB groups

Apellániz

Barbá

Aranda

et al. 2022

A&A

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“…Historically, RWs were often brighter, higher mass (OB) stars, as these stars were easier to observe compared to stars with lower mass, however, this has changed over the past few years (e.g. Tetzlaff et al 2011; de la Fuente Marcos & de la Fuente Marcos 2018; Yeom et al 2019;McBride & Kounkel 2019;Schoettler et al 2020;Bischoff et al 2020;Platais et al 2020). The advent of the Gaia telescope and in particular the second data release (DR2) in April 2018 (Gaia Collaboration et al 2016, 2018a has allowed the discovery of a much larger number of RWs, WWs, hyper-runaway and even faster hypervelocity stars than ever before (e.g.…”

Section: Introductionmentioning

confidence: 99%

Constraining the initial conditions of NGC 2264 using ejected stars found in Gaia DR2

Schoettler,

Parker,

de Bruijne

2021

Preprint

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Fast, ejected stars have been found around several young star-forming regions, such as the Orion Nebula Cluster (ONC). These ejected stars can be used to constrain the initial density, spatial and kinematic substructure when compared to predictions from 𝑁-body simulations. We search for runaway and slower walkaway stars using Gaia DR2 within 100 pc of NGC 2264, which contains subclustered regions around higher-mass OB-stars (S Mon, IRS 1 and IRS 2). We find five runaways and nine walkaways that trace back to S Mon and six runaways and five walkaways that trace back to IRS 1/2 based on their 3D-kinematics. We compare these numbers to a range of 𝑁-body simulations with different initial conditions. The number of runaways/walkaways is consistent with initial conditions with a high initial stellar density (∼10 000 M pc −3 ), a high initial amount of spatial substructure and either a subvirial or virialised ratio for all subclusters. We also confirm the trajectories of our ejected stars using the data from Gaia EDR3, which reduces the number of runaways from IRS 1/2 from six to four but leaves the number of runaways from S Mon unchanged. The reduction in runaways is due to smaller uncertainties in the proper motion and changes in the parallax/distance estimate for these stars in Gaia EDR3. We find further runaway/walkaway candidates based on proper motion alone in Gaia DR2, which could increase these numbers once radial velocities are available. We also expect further changes in the candidate list with upcoming Gaia data releases.

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“…Similar values were also found by Jones & Walker (1988) for optical stars covering a larger area of the ONC. Recent values of proper motion dispersions in the ONC have been estimated at optical and near infrared, to be (σ α , σ δ )=(0.73 ± 0.05, 1.12 ± 0.10) mas yr −1 using Gaia DR2 data (Kuhn et al 2019); (σ α , σ δ )=(0.83 ± 0.02, 1.12 ± 0.03) mas yr −1 using HST and Keck II NIRC2 data (Kim et al 2019); (σ α , σ δ )=(0.89 ± 0.03, 1.21 ± 0.04) mas yr −1 using HST data (Platais et al 2020). In the case of the VLBA data set the proper motion dispersion values are slightly larger.…”

Section: Trapezium Region Kinematicsmentioning

confidence: 99%

A VLBA Survey of Radio Stars in the Orion Nebula Cluster. II. Astrometry

Dzib

Forbrich

Reid

et al. 2021

ApJ

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From Very Long Baseline Array (VLBA) observations we previously identified a population of 123 young stellar systems with nonthermal radio emission toward the core of the Orion Nebula Cluster (ONC). We find optical sources in the Gaia DR2 catalog for 34 of them within 0. 2 of the radio positions. Most of the radio sources are likely companions of Gaia detections. However, there are 11 stars whose VLBA position differ from Gaia by < 1.6 mas, and some of these radio sources probably are the direct counterparts of the optical stars. We are able to obtain radio proper motions for 23 stars. Combining the stellar proper motions derived from the VLBA and Gaia DR2 data we find the global motion and velocity dispersion of the ONC to be (µ α * , µ δ )=(1.20± 0.09, 0.18 ± 0.09) mas yr −1 and (σ µα * , σ µ δ )=(0.84 ± 0.09, 1.30 ± 0.09) mas yr −1 . Finally, we looked for ordered motions by estimating the means of scalar and vectorial products, which results in v •r = −0.61 ± 1.00 km s −1 and v ×r = 0.57 ± 0.95 km s −1 . These do not show indications that the young stellar cluster is in expansion, contraction or rotation.

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Hubble Space Telescope Astrometry in the Orion Nebula Cluster: Census of Low-mass Runaways

Cited by 20 publications

References 39 publications

The Villafranca catalog of Galactic OB groups

The Villafranca catalog of Galactic OB groups

Constraining the initial conditions of NGC 2264 using ejected stars found in Gaia DR2

A VLBA Survey of Radio Stars in the Orion Nebula Cluster. II. Astrometry

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