scholarly journals Molecules in Dense Clouds And Protostars

1971 ◽  
Vol 2 ◽  
pp. 366-377
Author(s):  
P. G. Mezger
Keyword(s):  
Line Emission ◽  
Tauri Star ◽  
Evolutionary Stage ◽  
Solar Mass ◽  
Low Mass Stars ◽  
Dark Clouds ◽  
Physical Conditions ◽  
Dust Clouds ◽  
T Tauri ◽  
Low Mass

AbstractThis paper deals with the interpretation of molecular line emission from class I OH/H2O emission centers associated with compact HII regions and with the OH 18 cm emission from dark clouds in T-Tauri star associations. Observational evidence is presented, that class IOH/H2O emission centers represent a particular stage in the evolution of a massive star (or a group of massive stars) whereas protostars of lower mass apparently do not go through such a stage.It appears that in associations the low-mass stars are formed first and the massive O-stars are formed last. T-Tauri star associations may represent an early evolutionary stage of a star association where low-mass stars are formed. Evidence is presented that the physical conditions in some parts of the Taurus complex of dust clouds and T-Tauri stars are appropriate for the formation of single stars of about a solar mass.

Star Formation, Supernovae and the Structure of Disk Galaxies

1988 ◽  
Vol 101 ◽  
pp. 493-508
Author(s):  
Michael A. Dopita ◽  
Mt. Stromlo
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Collective Effects ◽  
Disk Galaxies ◽  
Solar Mass ◽  
Low Mass Stars ◽  
T Tauri ◽  
Steady Rate ◽  
Supernova Explosions ◽  
Low Mass

AbstractA physical model for bi-modal star formation and the structure of the interstellar medium and the self-regulating evolution of disk galaxies is presented. Stars heavier than about one solar mass are produced as a result of collisions of molecular clouds or in cloud crushing events whereas low-mass stars are produced at a steady rate in dense molecular clouds and the T-Tauri winds resulting maintain the support of these clouds against rapid collapse and fragmentation. Supernova explosions and stellar winds associated with the massive stars maintain the phase structure, and the scale height of the gas. The collective effects of these energetic processes may create a hole in the disk gas, and allow a galactic wind of metalenriched gas to develop.

scholarly journals Dense Cores and Young Stars in Dark Clouds

1987 ◽  
Vol 115 ◽  
pp. 33-43
Author(s):  
Philip C. Myers
Keyword(s):  
Circumstellar Disks ◽  
T Tauri Stars ◽  
Low Mass Stars ◽  
Iras Source ◽  
Dark Clouds ◽  
Dense Cores ◽  
T Tauri ◽  
Circumstellar Extinction ◽  
Molecular Lines ◽  
Low Mass

Dark clouds within a few hundred pc of the Sun contain hundreds of condensations with typical size 0.1 pc, density 104 molecules per cubic cm, mass 1 M⊙, and temperature 10 K. These “dense cores” are defined by maps of molecular lines, such as the (J,K)=(1,1) line of ammonia at 1.3 cm wavelength. They are associated with regions of opaque visual obscuration, groups of T Tauri stars, and other cores. They are closely correlated with steep-spectrum, low-luminosity (1-10 L⊙) IRAS sources! of about 60 cores with ammonia maps, half have an IRAS source within one map diameter. Thus cores form low-mass stars, which are probably precursors of T Tauri stars. Simple models indicate that time for a core to wait before collapsing, to collapse and form a star, and to disperse are each of order 105 yr. Cores with stars have broader lines and bigger velocity gradients than cores without stars, suggesting interaction between the star and the core due to gravity and/or outflow. Stars in cores have about 30 mag greater circumstellar extinction, and greater likelihood of CO outflow, than stars near, but not in, cores. Models of the 1-100 μm spectra of stars in cores suggest that inside of ∼100 A.U., the typical star suffers relatively little line-of-sight extinction but is accompanied by a source of significant luminosity at 5-25 μm. Models involving circumstellar disks provide good fits to the observed spectra.

scholarly journals Evidence of Collective Formation of Low Mass Stars in the Dark Cloud Kh141

1987 ◽  
Vol 115 ◽  
pp. 64-66
Author(s):  
Yoshio Tomita ◽  
Hiroshi Ohtani
Keyword(s):  
Star Formation ◽  
Massive Stars ◽  
T Tauri Stars ◽  
Low Mass Stars ◽  
Dark Cloud ◽  
T Tauri ◽  
Low Mass ◽  
Cloud Complex

To find evidence for collective star formation without massive stars in the dark cloud complex Kh141 (Saito 1980), a search for T-Tauri stars has been made.

scholarly journals The Frequency of YY Orionis Objects among the T Tauri Stars

1977 ◽  
Vol 42 ◽  
pp. 80-87 ◽  
Author(s):  
I. Appenzeller
Keyword(s):  
Statistical Analysis ◽  
Present Theory ◽  
T Tauri Stars ◽  
Early Evolution ◽  
Low Mass Stars ◽  
T Tauri ◽  
Uv Excess ◽  
Low Mass ◽  
Good Agreement

A list of 24 T Tauri stars belonging to the YY Orionis subclass is presented. From a statistical analysis it is estimated that at least 75% (and possibly all) UV-excess T Tauri stars are YY Orionis stars. Since about 50% of all known T Tauri stars show a strong UV-excess, the percentage of YY Orionis stars among the T Tauri stars is estimated to be 40 - 50%. This relative high percentage is in good agreement with the present theory of the formation and early evolution of low mass stars.

scholarly journals A hot Jupiter orbiting a 2-million-year-old solar-mass T Tauri star

Nature ◽  
2016 ◽  
Vol 534 (7609) ◽  
pp. 662-666 ◽  
Author(s):  
J. F. Donati ◽  
C. Moutou ◽  
L. Malo ◽  
C. Baruteau ◽  
L. Yu ◽  
...  
Keyword(s):  
Tauri Star ◽  
Solar Mass ◽  
T Tauri ◽  
Hot Jupiter

scholarly journals DISCOVERY AND OBSERVATIONS OF ASASSN-13db, AN EX LUPI-TYPE ACCRETION EVENT ON A LOW-MASS T TAURI STAR

2014 ◽  
Vol 785 (2) ◽  
pp. L35 ◽  
Author(s):  
Thomas W.-S. Holoien ◽  
Jose L. Prieto ◽  
K. Z. Stanek ◽  
C. S. Kochanek ◽  
B. J. Shappee ◽  
...  
Keyword(s):  
Tauri Star ◽  
T Tauri ◽  
Low Mass

scholarly journals Circumstellar Disks in Very Young Embedded Clusters

2013 ◽  
Vol 8 (S299) ◽  
pp. 165-166
Author(s):  
Naibí Mariñas ◽  
Elizabeth A. Lada ◽  
Paula S. Teixeira ◽  
Charles J. Lada
Keyword(s):  
Circumstellar Disks ◽  
Solar Mass ◽  
Low Mass Stars ◽  
Near Ir ◽  
Lower Disk ◽  
Low Mass ◽  
Embedded Clusters ◽  
Ir Photometry

AbstractWe used FLAMINGOS near-IR photometry and spectroscopy and Spitzer mid-IR photometry to study disk fractions in the 1 to 2 Myr old NGC2264 clusters. We find that stars with masses < 0.3 solar masses have lower disk fractions than stars of solar mass or higher at these early ages. We also find that most disks disappear within the first 4 Myr, which is consistent with previous studies of disk lifetimes. Our study suggests that either some very low mass stars form without disks or that their disks are less massive and/or colder than predicted from models and not detected with Spitzer/Flamingos sensitivities.

scholarly journals The rotation of very low-mass stars and brown dwarfs

2007 ◽  
Vol 3 (S243) ◽  
pp. 241-248
Author(s):  
Jochen Eislöffel ◽  
Alexander Scholz
Keyword(s):  
Angular Momentum ◽  
Brown Dwarfs ◽  
Magnetic Interaction ◽  
Stellar Winds ◽  
Solar Mass ◽  
Low Mass Stars ◽  
Angular Momentum Loss ◽  
Rotational Evolution ◽  
Solar Type ◽  
Low Mass

AbstractThe evolution of angular momentum is a key to our understanding of star formation and stellar evolution. The rotational evolution of solar-mass stars is mostly controlled by magnetic interaction with the circumstellar disc and angular momentum loss through stellar winds. Major differences in the internal structure of very low-mass stars and brown dwarfs – they are believed to be fully convective throughout their lives, and thus should not operate a solar-type dynamo – may lead to major differences in the rotation and activity of these objects. Here, we report on observational studies to understand the rotational evolution of the very low-mass stars and brown dwarfs.

scholarly journals HIGH-RESOLUTION OBSERVATIONS OF DUST CONTINUUM EMISSION AT 340 GHz FROM THE LOW-MASS T TAURI STAR FN TAURI

2010 ◽  
Vol 712 (1) ◽  
pp. 397-404 ◽  
Author(s):  
Munetake Momose ◽  
Nagayoshi Ohashi ◽  
Tomoyuki Kudo ◽  
Motohide Tamura ◽  
Yoshimi Kitamura
Keyword(s):  
High Resolution ◽  
Tauri Star ◽  
Continuum Emission ◽  
T Tauri ◽  
Low Mass

scholarly journals Infalling Streamer-Disk-Outflow System in a Nearby High-mass Star Formation Region

2021 ◽  
Author(s):  
Xi Chen ◽  
Zhiyuan Ren ◽  
Da-Lei Li ◽  
Tie Liu ◽  
Ke Wang ◽  
...  
Keyword(s):  
Direct Detection ◽  
Theoretical Models ◽  
Young Stellar Objects ◽  
High Mass ◽  
Similar Process ◽  
Mass Star ◽  
Solar Mass ◽  
Low Mass Stars ◽  
Stellar Objects ◽  
Low Mass

Abstract Theoretical models and numerical simulations suggest that high mass star (with mass > 8 solar mass) can be formed either via monolithic collapse of a massive core or competitive accretion, but the dominant mechanism is currently unclear. Although recent high resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) have detected physical and kinematic features, such as disks, outflows and filamentary structures surrounding the high mass young stellar objects (HMYSO), direct detection of the infalling gas towards the HMYSO is still the key to distinguish the different scenarios. Chemically fresh gas inflows have been detected towards low-mass stars being formed, which are consistent with the accretion-disk-outflow process. In this work we report the detection of a chemically fresh inflow which is feeding HMYSO growth in the nearby high mass star-forming region G352.63-1.07. High quality images of the dust and molecular lines from both ALMA and the Submillimeter Array (SMA) have consistently revealed a gravitationally-controlled gas inflow towards a rotating structure (disk or torus) around the HMYSO. The HMYSO is also observed to have an outflow, but it can be clearly separated from the inflow. These kinematic features provide observational evidence to support the conjecture that high-mass stars can be formed in a similar process to that observed in the low-mass counterparts. The chemically fresh infalling streamers could also be related with the disk configuration, fragmentation and accretion bursts that occur in both simulations and observations.

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