The spectral type of CHS 7797 - an intriguing very low mass periodic variable in 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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Definitions, Summary, and Some Issues

Highlights of Astronomy ◽

10.1017/s1539299600013216 ◽

2002 ◽

Vol 12 ◽

pp. 179-181

Author(s):

Peter S. Conti

Keyword(s):

Spectral Type ◽

Massive Star ◽

Massive Stars ◽

Mass Star ◽

Mass Limit ◽

Physical Processes ◽

Intermediate Mass ◽

Observable Quantity ◽

Low Mass ◽

Final Evolution

This Joint Discussion has been titled Massive Star Birth. Perhaps it is appropriate here to define what we mean by a massive star. The very word massive suggests we consider aminimummassMbelow which one would speak of low (or intermediate) mass evolution, and above which is the realm of massive stars. It is natural to take this mass limit as that in which a (single) star will end its life as a supernova: 8M⊙. This corresponds to a (minimum) luminosityLof a few × 103L⊙, a (minimum)Teff of 20000 K, and a ZAMS spectral type of about B1.5V. Note that this mass division refers to the final evolution of a star, and might well have nothing to do with difference in physical processes between massive and low mass starbirth. For example, the minimumTeff for a star to produce an UCHII region, a readily observable quantity, corresponds to aTeffcloser to 30000 K and a mass of 15M⊙.

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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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The White Dwarf Binary Pathways Survey – IV. Three close white dwarf binaries with G-type secondary stars

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3815 ◽

2020 ◽

Vol 501 (2) ◽

pp. 1677-1689

Author(s):

M S Hernandez ◽

M R Schreiber ◽

S G Parsons ◽

B T Gänsicke ◽

F Lagos ◽

...

Keyword(s):

Spectral Type ◽

White Dwarf ◽

Binary Stars ◽

Cataclysmic Variable ◽

Common Envelope ◽

History Of ◽

Low Mass ◽

Orbital Periods ◽

M Dwarf

ABSTRACT Constraints from surveys of post-common envelope binaries (PCEBs) consisting of a white dwarf plus an M-dwarf companion have led to significant progress in our understanding of the formation of close white dwarf binary stars with low-mass companions. The white dwarf binary pathways project aims at extending these previous surveys to larger secondary masses, i.e. secondary stars of spectral-type AFGK. Here, we present the discovery and observational characterization of three PCEBs with G-type secondary stars and orbital periods between 1.2 and 2.5 d. Using our own tools as well as MESA, we estimate the evolutionary history of the binary stars and predict their future. We find a large range of possible evolutionary histories for all three systems and identify no indications for differences in common envelope evolution compared to PCEBs with lower mass secondary stars. Despite their similarities in orbital period and secondary spectral type, we estimate that the future of the three systems is very different: TYC 4962-1205-1 is a progenitor of a cataclysmic variable system with an evolved donor star, TYC 4700-815-1 will run into dynamically unstable mass transfer that will cause the two stars to merge, and TYC 1380-957-1 may appear as supersoft source before becoming a rather typical cataclysmic variable star.

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Discovery of a Tight Brown Dwarf Companion to the Low Mass Star LHS 2397a

Symposium - International Astronomical Union ◽

10.1017/s0074180900210693 ◽

2003 ◽

Vol 211 ◽

pp. 261-264 ◽

Cited By ~ 2

Author(s):

Melanie Freed ◽

Laird M. Close ◽

Nick Siegler

Keyword(s):

Adaptive Optics ◽

Spectral Type ◽

Proper Motion ◽

Near Infrared ◽

Mass Star ◽

Infrared Photometry ◽

Brown Dwarf ◽

Dynamical Mass ◽

Low Mass ◽

Adaptive Optics System

Using the adaptive optics system, Hōkūpa'a, at Gemini-North, we have directly imaged a companion around the UKIRT faint standard M8 star, LHS 2397a (FS 129) at a separation of 2.96 AU. Near-Infrared photometry obtained on the companion has shown it to be an L7.5 brown dwarf and confirmed the spectral type of the primary to be an M8. We also derive a substellar mass of the companion of 0.068M⊙, although masses in the range (0.061 – 0.069) are possible, and the primary mass as 0.090M⊙ (0.089 – 0.094). Reanalysis of archival imaging from HST has confirmed the secondary as a common proper motion object. This binary represents the first clear example of a brown dwarf companion within 4 AU of a low mass star, and should be the first L7.5 to have a dynamical mass. As part of a larger survey of M8-M9 stars, this object may indicate that there is no “brown dwarf desert” around low mass primaries.

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A Relative Age Test of Pre-Main Sequence Evolutionary Models Based on the Young Quadruple System GG Tauri

Symposium - International Astronomical Union ◽

10.1017/s0074180900225540 ◽

2001 ◽

Vol 200 ◽

pp. 464-467

Author(s):

Russel J. White

Keyword(s):

Spectral Type ◽

Temperature Scale ◽

Main Sequence ◽

Evolutionary Models ◽

Low Mass Stars ◽

Relative Age ◽

Wide Range ◽

Quadruple System ◽

Low Mass

The components of the young hierarchical quadruple GG Tau, which span a wide range in spectral type (K7 – M7.5), are used to test both evolutionary models and the temperature scale for very young, low mass stars under the assumption of coeval formation. Of the evolutionary models tested which extend into the substellar regime, those of Baraffe et al. yield the most consistent ages when combined with a temperature scale intermediate between that of dwarfs and giants. The Palla & Stahler and Siess et al. models are also capable of yielding a coeval age down to their lowest mass (0.1 M⊙). These latter two models, which extend to much higher masses than the Baraffe et al. models, agree reasonably well with the Baraffe et al. models at 1.0 M⊙ and thus could be combined to construct a set evolutionary models that extends from Substellar to several solar masses.

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A spectroscopic analysis of the Trapezium Cluster stars

Symposium - International Astronomical Union ◽

10.1017/s007418090021334x ◽

2003 ◽

Vol 212 ◽

pp. 749-750

Author(s):

Sergio Simón-Díaz ◽

Artemio Herrero ◽

César Esteban

Keyword(s):

Spectral Analysis ◽

Spectral Type ◽

Spectroscopic Analysis ◽

Massive Stars ◽

The Other ◽

Orion Nebula ◽

Metal Line ◽

Synthetic Spectra ◽

H Ii Region

We consider the Orion Nebula (M 42) within a project aimed at studying the interaction between massive stars and their surrounding ISM. This is an H ii region ionized by θ1 Ori C, one of the four massive stars in the Trapezium Cluster. θ1 Ori C has the earliest spectral type (O7Vp) among them, emitting an ionizing flux several orders of magnitude larger than those of the other stars. We present a spectral analysis of the Trapezium Cluster stars to determine their stellar parameters. We use spectra between 4250 – 4750 Å and compare them with synthetic spectra obtained by means of an updated version of fastwind that includes an approximated treatment of metal-line blanketing.

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