scholarly journals Stellar Rotation of T Tauri Stars in the Orion Star-forming Complex

2021 ◽  
Vol 923 (2) ◽  
pp. 177
Author(s):  
Javier Serna ◽  
Jesus Hernandez ◽  
Marina Kounkel ◽  
Ezequiel Manzo-Martínez ◽  
Alexandre Roman-Lopes ◽  
...  
Keyword(s):  
Large Scale ◽  
Rotational Velocity ◽  
T Tauri Stars ◽  
Evolutionary Models ◽  
Stellar Rotation ◽  
Low Mass Stars ◽  
Star Forming ◽  
T Tauri ◽  
Low Mass ◽  
Early Phases

Abstract We present a large-scale study of stellar rotation for T Tauri stars in the Orion star-forming complex. We use the projected rotational velocity ( v sin ( i ) ) estimations reported by the APOGEE-2 collaboration as well as individual masses and ages derived from the position of the stars in the HR diagram, considering Gaia-EDR3 parallaxes and photometry plus diverse evolutionary models. We find an empirical trend for v sin ( i ) decreasing with age for low-mass stars (0.4M ⊙ < M * < 1.2M ⊙). Our results support the existence of a mechanism linking v sin ( i ) to the presence of accreting protoplanetary disks, responsible for regulating stellar rotation on timescales of about 6 Myr, which is the timescale in which most of the T Tauri stars lose their inner disk. Our results provide important constraints to models of rotation in the early phases of evolution of young stars and their disks.

scholarly journals Circumstellar maher of young low-mass stars: Observations versus theory

1987 ◽  
Vol 122 ◽  
pp. 23-38 ◽  
Author(s):  
Claude Bertout
Keyword(s):  
T Tauri Stars ◽  
Young Stellar Objects ◽  
Low Mass Stars ◽  
Stellar Objects ◽  
Star Forming ◽  
T Tauri ◽  
Region I ◽  
Low Mass ◽  
Infrared Sources

After presenting NGC 7129 as a prototypical star-forming region, I discuss what can be learned from the radio spectra of embedded infrared sources. I then review available observational evidence for disks around young stellar objects, with emphasis on accretion disks around T Tauri stars. Finally, new results on the role of magnetic fields in the circumstellar activity of T Tauri stars are presented.

scholarly journals NMA Imaging of Envelopes and Disks around Low Mass Protostars and T Tauri Stars

1997 ◽  
Vol 182 ◽  
pp. 381-390
Author(s):  
Yoshimi Kitamura ◽  
Masao Saito ◽  
Ryohei Kawabe ◽  
Kazuyoshi Sunada
Keyword(s):  
Accretion Disks ◽  
Molecular Clouds ◽  
Protoplanetary Disks ◽  
Hierarchical Structures ◽  
T Tauri Stars ◽  
Mass Star ◽  
Low Mass Stars ◽  
Star Forming ◽  
T Tauri ◽  
Low Mass

We are intensively studying low mass star formation with the radio telescopes at Nobeyama in Japan. Using both the Nobeyama 45 m dish equipped with a 2 × 2 array receiver and the Nobeyama Millimeter Array (NMA), we can cover a very wide spatial range from overall molecular clouds down to compact protoplanetary disks. With the 45 m dish we are investigating hierarchical structures of molecular clouds including star-forming cores. With NMA we are imaging disklike structures (i.e., envelopes, accretion disks, and protoplanetary disks) around protostars and T Tauri stars. Recently, we have completed our survey for dense disklike envelopes around eleven Class 0 & I protostars by NMA. In this paper, we will present our recent results of the disklike envelopes in addition to the previous NMA results of the disks around three T Tauri stars. On the basis of the data, we will discuss the evolution of the disklike structures (dense envelopes → tenuous ones → dispersing ones → accretion disks → protoplanetary ones), and propose a new scenario for the formation of low mass stars.

scholarly journals Very Low Mass Stars and Brown Dwarfs in Taurus

2003 ◽  
Vol 211 ◽  
pp. 143-144
Author(s):  
Russel White ◽  
Gibor Basri
Keyword(s):  
High Resolution ◽  
Brown Dwarfs ◽  
Optical Spectra ◽  
T Tauri Stars ◽  
Low Mass Stars ◽  
Star Forming ◽  
T Tauri ◽  
Low Mass

We present high resolution optical spectra obtained with the Keck I telescope of low mass T Tauri stars and brown dwarfs in the Taurus star forming region. Based on the inferred photospheric and circumstellar properties, we conclude that objects in Taurus with masses as low as 50 Jupiters form and evolve in the same way as higher-mass T Tauri stars, but with smaller disks and shorter disk lifetimes.

scholarly journals Very Low-Luminosity Objects in Star-Forming Regions

1998 ◽  
Vol 11 (1) ◽  
pp. 423-424
Author(s):  
Motohide Tamura ◽  
Yoichi Itoh ◽  
Yumiko Oasa ◽  
Alan Tokunaga ◽  
Koji Sugitani
Keyword(s):  
Brown Dwarfs ◽  
Mass Function ◽  
T Tauri Stars ◽  
Initial Mass Function ◽  
Formation Mechanisms ◽  
Star Forming ◽  
Star Forming Regions ◽  
T Tauri ◽  
Low Mass ◽  
Stellar Sources

Abstract In order to tackle the problems of low-mass end of the initial mass function (IMF) in star-forming regions and the formation mechanisms of brown dwarfs, we have conducted deep infrared surveys of nearby molecular clouds. We have found a significant population of very low-luminosity sources with IR excesses in the Taurus cloud and the Chamaeleon cloud core regions whose extinction corrected J magnitudes are 3 to 8 mag fainter than those of typical T Tauri stars in the same cloud. Some of them are associated with even fainter companions. Follow-up IR spectroscopy has confirmed for the selected sources that their photospheric temperature is around 2000 to 3000 K. Thus, these very low-luminosity young stellar sources are most likely very low-mass T Tauri stars, and some of them might even be young brown dwarfs.

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.

Magnetic fields of T Tauri stars and inner accretion discs

2018 ◽  
Vol 14 (A30) ◽  
pp. 121-121
Author(s):  
Jean-Francois Donati
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Near Infrared ◽  
High Sensitivity ◽  
T Tauri Stars ◽  
Accretion Discs ◽  
High Resolution Spectroscopy ◽  
T Tauri ◽  
Low Mass ◽  
The Impact

AbstractMagnetic fields play a key role in the early life of stars and their planets, as they form from collapsing dense cores that progressively flatten into large-scale accretion discs and eventually settle as young suns orbited by planetary systems. Pre-main-sequence phases, in which central protostars feed from surrounding planet-forming accretion discs, are especially crucial for understanding how worlds like our Solar System are born.Magnetic fields of low-mass T Tauri stars (TTSs) are detected through high-resolution spectroscopy and spectropolarimetry (e.g., Johns Krull 2007), whereas their large-scale topologies can be inferred from time series of Zeeman signatures using tomographic techniques inspired from medical imaging (Donati & Landstreet 2009). Large-scale fields of TTSs are found to depend on the internal structure of the newborn star, allowing quantitative models of how TTSs magnetically interact with their inner accretion discs, and the impact of this interaction on the subsequent stellar evolution (e.g., Romanova et al. 2002, Zanni & Ferreira 2013).With its high sensitivity to magnetic fields, SPIRou, the new near-infrared spectropolarimeter installed in 2018 at CFHT (Donati et al. 2018), should yield new advances in the field, especially for young embedded class-I protostars, thereby bridging the gap with radio observations.

scholarly journals Disks around Young Brown Dwarfs

2003 ◽  
Vol 211 ◽  
pp. 133-136
Author(s):  
Michael C. Liu
Keyword(s):  
Brown Dwarfs ◽  
Circumstellar Disks ◽  
Disk Accretion ◽  
Low Mass Stars ◽  
Star Forming ◽  
Star Forming Regions ◽  
Planetary Mass ◽  
T Tauri ◽  
Hα Emission ◽  
Low Mass

We present some results from a systematic survey for disks around spectroscopically identified young brown dwarfs and very low mass stars. We find that ≈75% of our sample show intrinsic IR excesses, indicative of circum(sub)stellar disks. The observed excesses are well-correlated with Hα emission, consistent with a common disk accretion origin. Because the excesses are modest, conventional analyses using only IR colors would have missed most of the sources with disks. In the same star-forming regions, we find that disks around brown dwarfs and T Tauri stars are contemporaneous; assuming coevality, this demonstrates that substellar disks are at least as long-lived as stellar disks. Altogether, the frequency and properties of circumstellar disks are similar from the stellar regime down to the substellar and planetary-mass regime. This offers compelling evidence of a common origin for most stars and brown dwarfs.

scholarly journals Peter Pan discs: finding Neverland’s parameters

2020 ◽  
Vol 496 (1) ◽  
pp. L111-L115
Author(s):  
Gavin A L Coleman ◽  
Thomas J Haworth
Keyword(s):  
Initial Conditions ◽  
Mass Star ◽  
Evolutionary Models ◽  
Peter Pan ◽  
Low Mass Stars ◽  
Star Forming ◽  
Star Forming Regions ◽  
Accretion Rates ◽  
Order Of Magnitude ◽  
Low Mass

ABSTRACT Peter Pan discs are a recently discovered class of long-lived discs around low-mass stars that survive for an order of magnitude longer than typical discs. In this paper, we use disc evolutionary models to determine the required balance between initial conditions and the magnitude of dispersal processes for Peter Pan discs to be primordial. We find that we require low transport (α ∼ 10−4), extremely low external photoevaporation (${\le}10^{-9}\, {\rm M}_{\odot }\, {\rm yr^{-1}}$), and relatively high disc masses (&gt;0.25M*) to produce discs with ages and accretion rates consistent with Peter Pan discs. Higher transport (α = 10−3) results in disc lifetimes that are too short and even lower transport (α = 10−5) leads to accretion rates smaller than those observed. The required external photoevaporation rates are so low that primordial Peter Pan discs will have formed in rare environments on the periphery of low-mass star-forming regions, or deeply embedded, and as such have never subsequently been exposed to higher amounts of UV radiation. Given that such an external photoevaporation scenario is rare, the required disc parameters and accretion properties may reflect the initial conditions and accretion rates of a much larger fraction of the discs around low-mass stars.

scholarly journals Nature of Emission-Line Stars in the Outer Orion Region

1995 ◽  
Vol 148 ◽  
pp. 376-379
Author(s):  
Makoto Nakano ◽  
Peter J. McGregor
Keyword(s):  
Emission Line ◽  
Large Scale ◽  
Near Infrared ◽  
Infrared Photometry ◽  
Low Mass Stars ◽  
Strong Emission ◽  
Star Catalog ◽  
T Tauri ◽  
Low Mass ◽  
Cloud Complex

AbstractNear-infrared photometry is reported for 76 emission-line stars in outer regions of the Orion molecular cloud complex. Most of our program stars are selected from the Hα emission-line star catalog of the large-scale Kiso Schmidt survey of the Orion region. We confirm that most of the emission-line stars with strong emission detected in the Kiso survey are typical T Tauri stars with masses in the range 0.5 to 2 M⊙. Low mass stars have therefore continued to form in the outer parts of the Orion region, away from present day massive molecular clouds, until at least as recently as a few million year ago.

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