Evidence of early disk-locking among low-mass members   of the Orion Nebula Cluster

AbstractWe report on the results of a binary survey in the outer parts of the Orion Nebula Cluster, 0.7 to 2 pc from the cluster center. The results should help to decide if the binary formation rate was lower in Orion than in Taurus-Auriga, or if many binaries formed initially, but were destroyed in close stellar encounters. We find that the binary frequency of low-mass stars does not depend on the distance to the cluster center. The companion star frequency of intermediate- to high-mass stars shows a trend to decrease with cluster radius, but the statistical significance of this trend is rather weak.

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Rotational studies of very low mass stars and brown dwarfs in the Orion Nebula Cluster

10.1063/1.3099080 ◽

2009 ◽

Author(s):

Maria V. Rodríguez-Ledesma ◽

Reinhard Mundt ◽

Jochen Eislöffel ◽

William Herbst ◽

Eric Stempels

Keyword(s):

Brown Dwarfs ◽

Orion Nebula ◽

Low Mass Stars ◽

Low Mass

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Evidence of early disk-locking among low-mass members of the Orion Nebula Cluster(Corrigendum)

Astronomy and Astrophysics ◽

10.1051/0004-6361/200913125e ◽

2011 ◽

Vol 533 ◽

pp. C3

Author(s):

K. Biazzo ◽

C. H. F. Melo ◽

L. Pasquini ◽

S. Randich ◽

J. Bouvier ◽

...

Keyword(s):

Orion Nebula ◽

Low Mass

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Frequency distribution of x-ray flares for low-mass young stellar objects in the Orion nebula

Astrophysics ◽

10.1007/s10511-012-9256-3 ◽

2012 ◽

Vol 55 (4) ◽

pp. 505-514 ◽

Cited By ~ 1

Author(s):

A. A. Akopian

Keyword(s):

Frequency Distribution ◽

Young Stellar Objects ◽

Orion Nebula ◽

Stellar Objects ◽

X Ray ◽

Low Mass

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Direct Imaging of Circumstellar Disks in the Orion Nebula

International Astronomical Union Colloquium ◽

10.1017/s0252921100043177 ◽

1997 ◽

Vol 163 ◽

pp. 546-548

Author(s):

Mark J. McCaughrean

Keyword(s):

Near Infrared ◽

Hubble Space Telescope ◽

Circumstellar Disks ◽

Infrared Emission ◽

Orion Nebula ◽

Direct Imaging ◽

Stellar Photometry ◽

Inclination Angles ◽

Low Mass ◽

Lower Limits

AbstractWe present observations of the Orion Nebula made with the Hubble Space Telescope in which a number of stars are seen surrounded by dark silhouettes seen projected against the bright background HII region. We find a variety of morphologies, all consistent with thin circumstellar disks spanning a range of diameters (50 to 1000 AU) and inclination angles (0 to > 80 degrees). The silhouette intensity profiles cannot be fit by standard disk models in which the surface density follows a radial power law with an exponent in the range −0.75 to −1.5. Rather, the data are best fit by opaque inner disks with exponential edges, and we discuss possible physical origins of this apparent truncation. Masses in the range 6 × l026−4 × 1030 g (i.e., up to 0.002 M⊙) are determined for the disks by assuming that the faint light measured from them is background light transmitted through the disk. However, these are strict lower limits on the true disk masses, as most of this light can be accounted for by PSF blurring and scattering in the HST optical train; the present observations are in fact consistent with completely opaque disks. Central stars are seen directly in five of the silhouettes, while the presence of a star is inferred in the sixth, where small reflection nebulae are seen above and below the plane of the near edge-on disk. Optical and near-infrared stellar photometry is consistent with young (~ 1 Myr) low-mass (0.3−1.5 M⊙) stars, with several showing evidence for excess near-infrared emission from the disk inner edge. These direct imaging observations are discussed in the wider context of circumstellar disks in the Orion Nebula and Trapezium Cluster, additionally revealed as compact ionized nebulae (so-called “proplyds”) in the vicinity of the central OB stars, and via infrared (>2µm) excesses in stellar photometry. Overall, disks are found to be common in the cluster (>50% of all stars), implying that they can survive the rigours of life near massive stars.

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3D shape of Orion A with Gaia DR2 An informed view on Star Formation Rates and Efficiencies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319001492 ◽

2018 ◽

Vol 14 (S345) ◽

pp. 27-33

Author(s):

Josefa E. Großschedl ◽

João Alves ◽

Stefan Meingast ◽

Birgit Hasenberger

Keyword(s):

Star Formation ◽

Formation Rate ◽

Young Stellar Objects ◽

Mass Star ◽

Orion Nebula ◽

Stellar Objects ◽

Star Forming ◽

The North ◽

Low Mass ◽

The Rich

AbstractThe giant molecular cloud Orion A is the closest massive star-forming region to earth (d ∼ 400 pc). It contains the rich Orion Nebula Cluster (ONC) in the North, and low-mass star-forming regions (L1641, L1647) to the South. To get a better understanding of the differences in star formation activity, we perform an analysis of the gas mass distribution and star formation rate across the cloud. We find that the gas is roughly uniformly distributed, while, oddly, the ONC region produced about a factor of ten more stars compared to the rest of the cloud. For a better interpretation of this phenomenon, we use Gaia DR2 parallaxes, to analyse distances of young stellar objects, using them as proxy for cloud distances. We find that the ONC region indeed lies at about 400 pc while the low-mass star-forming parts are inclined about 70∘ from the plane of the sky reaching until ∼470 pc. With this we estimate that Orion A is an about 90 pc long filamentary cloud (about twice as long as previously assumed), with its “Head” (the ONC region) being “bent” and oriented towards the galactic mid-plane. This striking new view allows us to perform a more robust analysis of this important star-forming region in the future.

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Binary Stars in the Orion Nebula Cluster

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307003912 ◽

2006 ◽

Vol 2 (S240) ◽

pp. 114-116

Author(s):

Rainer Köhler ◽

Monika G. Petr-Gotzens ◽

Mark J. McCaughrean ◽

Jerome Bouvier ◽

Gaspard Duchêne ◽

...

Keyword(s):

Adaptive Optics ◽

Binary Stars ◽

Main Sequence ◽

Cluster Center ◽

Orion Nebula ◽

Low Mass Stars ◽

Star Forming ◽

Star Forming Regions ◽

Low Mass ◽

Guide Star

AbstractWe report on a high-spatial-resolution survey for binary stars in the periphery of the Orion Nebula Cluster, at 5–15 arcmin (0.65 – 2 pc) from the cluster center. We observed 228 stars with adaptive optics systems, in order to find companions at separations of 0.13 – 1.12 arcsec (60 – 500 AU), and detected 13 new binaries. Combined with the results of Petr (1998), we have a sample of 275 objects, about half of which have masses from the literature and high probabilities to be cluster members. We used an improved method to derive the completeness limits of the observations, which takes into account the elongated point spread function of stars at relatively large distances from the adaptive optics guide star. The multiplicity of stars with masses >2 M⊙ is found to be significantly larger than that of low-mass stars. The companion star frequency of low-mass stars is comparable to that of main-sequence M-dwarfs, less than half that of solar-type main-sequence stars, and 3.5 to 5 times lower than in the Taurus-Auriga and Scorpius-Centaurus star-forming regions. We find the binary frequency of low-mass stars in the periphery of the cluster to be the same or only slightly higher than for stars in the cluster core (< 3′ from θ1C Ori). This is in contrast to the prediction of the theory that the low binary frequency in the cluster is caused by the disruption of binaries due to dynamical interactions. There are two ways out of this dilemma: Either the initial binary frequency in the Orion Nebula Cluster was lower than in Taurus-Auriga, or the Orion Nebula Cluster was originally much denser and dynamically more active. A detailed report of this work has been published in Astronomy & Astrophysics (Köhler et al. 2006).

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Rotation-disk connection for very low mass and substellar objects in the Orion Nebula Cluster

Astronomy and Astrophysics ◽

10.1051/0004-6361/200913494 ◽

2010 ◽

Vol 515 ◽

pp. A13 ◽

Cited By ~ 11

Author(s):

M. V. Rodríguez-Ledesma ◽

R. Mundt ◽

J. Eislöffel

Keyword(s):

Orion Nebula ◽

Substellar Objects ◽

Low Mass

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Rotational properties of the Orion nebular cluster revised

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307000634 ◽

2006 ◽

Vol 2 (S239) ◽

pp. 311-313

Author(s):

Natália R. Landin ◽

Paolo Ventura ◽

Francesca D'Antona ◽

Luiz T. S. Mendes ◽

Luiz P. R. Vaz

Keyword(s):

Boundary Conditions ◽

Observational Data ◽

Main Sequence ◽

Orion Nebula ◽

Low Mass Stars ◽

Physical Constraints ◽

Rotational Evolution ◽

Low Mass ◽

Stellar Masses

AbstractThe observational data of the Orion Nebula Cluster (ONC) is reanalyzed by means of new sets of pre-main sequence (PMS) evolutionary tracks including rotation, non-gray boundary conditions (BC's) and either low (LCE) or high convection efficiency (HCE), aiming better understanding of the appropriate physical constraints for the rotational evolution of the stars within the ONC. The role played by convection is a key aspect of our analysis, since there are conflicting results from theory and observations. We derived stellar masses and ages for the ONC by using both LCE and HCE and considered was the role of non-gray atmospheres. Our results show that the resulting mass distribution for the bulk of the ONC population is in the range 0.2-0.4M⊙ for our non-gray models, and in the range 0.1-0.3M⊙ for gray models. In agreement with previous works, we found that a large percentage (∼70%) of low-mass stars (M≤Mtr, where Mtr is a transition mass) in the ONC appears to be fast rotators (P<4days). Mtr depends on the model choosen, being Mtr=0.5 for LCE, Mtr=0.35 for HCE and, as found in previous works, Mtr=0.25 for gray models. Finally, our analysis indicates that a second parameter is needed for a proper description of convection in the PMS phase.

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