scholarly journals The Structure and Emission of the Accretion Shock in T Tauri Stars. II. The Ultraviolet‐Continuum Emission

2000 ◽  
Vol 544 (2) ◽  
pp. 927-932 ◽  
Author(s):  
Erik Gullbring ◽  
Nuria Calvet ◽  
James Muzerolle ◽  
Lee Hartmann
Keyword(s):  
T Tauri Stars ◽  
Continuum Emission ◽  
Ultraviolet Continuum ◽  
T Tauri ◽  
Accretion Shock

scholarly journals Aperture synthesis CS and 98 GHz continuum observations of protostellar IRAS sources in Taurus

1991 ◽  
Vol 147 ◽  
pp. 353-356
Author(s):  
N. Ohashi ◽  
R. Kawabe ◽  
M. Hayashi ◽  
M. Ishiguro
Keyword(s):  
Molecular Cloud ◽  
Total Mass ◽  
T Tauri Stars ◽  
Continuum Emission ◽  
Beam Size ◽  
Dust Grains ◽  
Dynamical Mass ◽  
T Tauri ◽  
Cloud Cores ◽  
The Continuum

The CS (J = 2 — 1) line and 98 GHz continuum emission have been observed for 11 protostellar IRAS sources in the Taurus molecular cloud with resolutions of 2.6″−8.8″ (360 AU—1200 AU) using the Nobeyama Millimeter Array (NMA). The CS emission is detected only toward embedded sources, while the continuum emission from dust grains is detected only toward visible T Tauri stars except for one embedded source, L1551-IRS5. This suggests that the dust grains around the embedded sources do not centrally concentrate enough to be detected with our sensitivity (∼4 m Jy r.m.s), while dust grains in disks around the T Tauri stars have enough total mass to be detected with the NMA. The molecular cloud cores around the embedded sources are moderately extended and dense enough to be detected in CS, while gas disks around the T Tauri are not detected because the radius of such gas disks may be smaller than 70 (50 K/Tex) AU. These results imply that the total amount of matter within the NMA beam size must increase when the central objects evolve into T Tauri stars from embedded sources, suggesting that the compact and highly dense disks around T Tauri stars are formed by the dynamical mass accretion during the embedded protostar phase.

scholarly journals Formation of Fe X-Fe XIV coronal lines in the accretion shock of T Tauri stars

2001 ◽  
Vol 369 (3) ◽  
pp. 965-970 ◽  
Author(s):  
S. A. Lamzin ◽  
H. C. Stempels ◽  
N. E. Piskunov
Keyword(s):  
T Tauri Stars ◽  
T Tauri ◽  
Accretion Shock

scholarly journals Evolution of Disks in the Course of Star Formation

1994 ◽  
Vol 140 ◽  
pp. 212-219
Author(s):  
Masahiko Hayashi
Keyword(s):  
Rotating Disk ◽  
Circumstellar Disks ◽  
T Tauri Stars ◽  
Continuum Emission ◽  
Circumstellar Disk ◽  
Upper Limit ◽  
Disk Mass ◽  
T Tauri ◽  
Dust Disk ◽  
Co Emission

AbstractObservations of circumstellar disks with Nobeyama Millimeter Array (NMA) are presented for the following two topics. The first one is on the continued NMA survey for 13 complete samples of protostar candidates associated with Taurus molecular cloud. The observation confirmed the previous result that protostar candidates do not have detectable 3 mm continuum emission except for the two sources L1551-IRS5 and IRAS 04365+2535. This sets the upper limit to the circumstellar disk mass to be ~0.03 Mʘ for the protostar candidates. The disk mass for protostar candidates tends to be smaller than that around young T Tauri stars, suggesting that it may increase in the course of evolution from protostars into T Tauri stars. The second topic is on the detection of CO (J=1-0) emission toward GG Tau. The observations with the 45-m telescope and with NMA show strong evidence of the CO emission arising from a rotating disk with its size significantly extended with respect to the dust disk. Depletion of CO gas in the GG Tau disk is discussed.

scholarly journals The Nobeyama Millimeter Array Survey for Protoplanetary Disks Around Protostar Candidates and T Tauri Stars in Taurus

1994 ◽  
Vol 140 ◽  
pp. 274-275
Author(s):  
Nagayoshi Ohashi ◽  
Ryohei Kawabe ◽  
Masahiko Hayashi ◽  
Masato Ishiguro
Keyword(s):  
Protoplanetary Disks ◽  
Circumstellar Disks ◽  
Stellar Mass ◽  
T Tauri Stars ◽  
Continuum Emission ◽  
Disk Mass ◽  
T Tauri ◽  
The Continuum

AbstractThe Nobeyama Millimeter Array Survey for protoplanetary disks has been made for 19 protostellar IRAS sources in Taurus; 13 were invisible protostars and 6 were youngest T Tauri stars. We observed the 98 GHz continuum and CS(J=2-1) line emissions simultaneously with spatial resolutions of 2.8”- 8.8” (360 AU-1,200 AU). Unresolved continuum emission was detected from 5 of 6 T Tauri stars and 2 of 13 protostar candidates. The continuum emission arose from compact circumstellar disks. Extended CS emission was detected around 2 T Tauri stars and 11 protostar candidates. There is a remarkable tendency for the detectability for the 98 GHz continuum emission to be small for protostar candidates. This tendency is explained if the mass of protoplanetary disks around protostars is not as large as that around T Tauri stars; the disk mass may increase with the increase of central stellar mass by dynamical accretion in the course of evolution from protostars to T Tauri stars.

scholarly journals X-ray emission from dense plasma in classical T Tauri stars: hydrodynamic modeling of the accretion shock

2008 ◽  
Vol 491 (2) ◽  
pp. L17-L20 ◽  
Author(s):  
G. G. Sacco ◽  
C. Argiroffi ◽  
S. Orlando ◽  
A. Maggio ◽  
G. Peres ◽  
...  
Keyword(s):  
Dense Plasma ◽  
Hydrodynamic Modeling ◽  
T Tauri Stars ◽  
X Ray ◽  
T Tauri ◽  
Accretion Shock

scholarly journals The Structure and Emission of the Accretion Shock in T Tauri Stars

1998 ◽  
Vol 509 (2) ◽  
pp. 802-818 ◽  
Author(s):  
Nuria Calvet ◽  
Erik Gullbring
Keyword(s):  
T Tauri Stars ◽  
T Tauri ◽  
Accretion Shock

scholarly journals The magnetic obliquity of accreting T Tauri stars

2020 ◽  
Vol 497 (2) ◽  
pp. 2142-2162
Author(s):  
Pauline McGinnis ◽  
Jérôme Bouvier ◽  
Florian Gallet
Keyword(s):  
Radial Velocity ◽  
Rotational Velocity ◽  
T Tauri Stars ◽  
Rotational Axis ◽  
Stellar Rotation ◽  
Magnetic Pole ◽  
T Tauri ◽  
Significant Difference ◽  
Tentative Evidence ◽  
Accretion Shock

ABSTRACT Classical T Tauri stars (CTTSs) accrete material from their discs through their magnetospheres. The geometry of the accretion flow strongly depends on the magnetic obliquity, i.e. the angle between the rotational and magnetic axes. We aim at deriving the distribution of magnetic obliquities in a sample of 10 CTTSs. For this, we monitored the radial velocity variations of the He i λ5876 Å line in these stars’ spectra along their rotational cycle. He i is produced in the accretion shock, close to the magnetic pole. When the magnetic and rotational axes are not aligned, the radial velocity of this line is modulated by stellar rotation. The amplitude of modulation is related to the star’s projected rotational velocity, vsin i, and the latitude of the hotspot. By deriving vsin i and He i λ5876 radial velocity curves from our spectra, we thus obtain an estimate of the magnetic obliquities. We find an average obliquity in our sample of 11.4° with an rms dispersion of 5.4°. The magnetic axis thus seems nearly, but not exactly aligned with the rotational axis in these accreting T Tauri stars, somewhat in disagreement with studies of spectropolarimetry, which have found a significant misalignment (≳20°) for several CTTSs. This could simply be an effect of low number statistics, or it may be due to a selection bias of our sample. We discuss possible biases that our sample may be subject to. We also find tentative evidence that the magnetic obliquity may vary according to the stellar interior and that there may be a significant difference between fully convective and partly radiative stars.

scholarly journals Disks Around T Tauri Stars

1994 ◽  
Vol 140 ◽  
pp. 203-211
Author(s):  
Anneila Sargent ◽  
Steven Beckwith
Keyword(s):  
Solar System ◽  
Solar Nebula ◽  
Chemical Properties ◽  
Velocity Fields ◽  
T Tauri Stars ◽  
Continuum Emission ◽  
Future Research ◽  
Molecular Line ◽  
Density Distributions ◽  
T Tauri

AbstractA variety of evidence suggests that at least 50% of T Tauri stars are surrounded by disks of gas and dust. Inferred disk properties are compatible with those generally attributed to the solar nebula, before the formation of planets. Millimeter-wave aperture synthesis mapping of molecular line and dust continuum emission from T Tauri stars provides a direct way to ascertain if disks are present. The technique enables detailed studies of disk temperature and density distributions, chemical properties and velocity fields. These results inform our understanding of both star formation and solar system evolution. We review the observations to date and discuss directions for future research.

scholarly journals Aperture synthesis CS and 98 GHz continuum observations of protostellar IRAS sources in Taurus

1991 ◽  
Vol 147 ◽  
pp. 353-356
Author(s):  
N. Ohashi ◽  
R. Kawabe ◽  
M. Hayashi ◽  
M. Ishiguro
Keyword(s):  
Molecular Cloud ◽  
Total Mass ◽  
T Tauri Stars ◽  
Continuum Emission ◽  
Beam Size ◽  
Dust Grains ◽  
Dynamical Mass ◽  
T Tauri ◽  
Cloud Cores ◽  
The Continuum

The CS (J = 2 — 1) line and 98 GHz continuum emission have been observed for 11 protostellar IRAS sources in the Taurus molecular cloud with resolutions of 2.6″−8.8″ (360 AU—1200 AU) using the Nobeyama Millimeter Array (NMA). The CS emission is detected only toward embedded sources, while the continuum emission from dust grains is detected only toward visible T Tauri stars except for one embedded source, L1551-IRS5. This suggests that the dust grains around the embedded sources do not centrally concentrate enough to be detected with our sensitivity (∼4 m Jy r.m.s), while dust grains in disks around the T Tauri stars have enough total mass to be detected with the NMA. The molecular cloud cores around the embedded sources are moderately extended and dense enough to be detected in CS, while gas disks around the T Tauri are not detected because the radius of such gas disks may be smaller than 70 (50 K/Tex) AU. These results imply that the total amount of matter within the NMA beam size must increase when the central objects evolve into T Tauri stars from embedded sources, suggesting that the compact and highly dense disks around T Tauri stars are formed by the dynamical mass accretion during the embedded protostar phase.

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