Analysis of magnetic field measurements for T Tau

Smirnov, D. A.; Romanova, M. M.; Ламзин, С. А.

doi:10.1134/1.1922532

Cited by 4 publications

(4 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Observations suggest a non-dipolar magnetic field near the stellar surface (see Sect. 2, and also, e.g., Safier, 1998;Kravtsova and Lamzin, 2003;Lamzin, 2003;Smirnov et al, 2005). If the dipole component dominates on the large scale, many properties of magnetospheric accretion will be similar to those described above, including the structure of the funnel streams and their physical properties.…”

Section: Numerical Simulations Of Magneto-spheric Accretionmentioning

confidence: 87%

Magnetospheric accretion in T Tauri stars

Bouvier

2003

EAS Publications Series

View full text Add to dashboard Cite

The inner 0.1 AU around accreting T Tauri stars hold clues to many physical processes that characterize the early evolution of solar-type stars. The accretion-ejection connection takes place at least in part in this compact magnetized region around the central star, with the inner disk edge interacting with the star's magnetosphere thus leading simultaneously to magnetically channeled accretion flows and to high velocity winds and outflows. The magnetic star-disk interaction is thought to have strong implications for the angular momentum evolution of the central system, the inner structure of the disk, and possibly for halting the migration of young planets close to the stellar surface. We review here the current status of magnetic field measurements in T Tauri stars, the recent modeling efforts of the magnetospheric accretion process, including both radiative transfer and multi-D numerical simulations, and summarize current evidence supporting the concept of magnetically-channeled accretion in young stars. We also discuss the limits of the models and highlight observational results which suggest that the star-disk interaction is a highly dynamical and time variable process in young stars.

show abstract

Section: Numerical Simulations Of Magneto-spheric Accretionmentioning

confidence: 87%

Magnetospheric accretion in T Tauri stars

Bouvier

2003

EAS Publications Series

View full text Add to dashboard Cite

show abstract

“…For example, a dipole with a 3 kG polar field strength (as suggested for BP Tau by Symington et al 2005) observed at an angle of 45 • would produce a net field of 690 G, well above current detection limits. Accretion hot spots are expected to have essentially no effect on net field measurements from spectropolarimetry (Smirnov et al 2005) since the acretion filling factors are typically ∼ 1% (Valenti et al 1993.…”

Section: Discussionmentioning

confidence: 99%

The Magnetic Fields of Classical T Tauri Stars

Johns–Krull

2007

ApJ

343

305

View full text Add to dashboard Cite

We report new magnetic field measurements for 14 classical T Tauri stars (CTTSs). We combine these data with one previous field determination in order to compare our observed field strengths with the field strengths predicted by magnetospheric accretion models. We use literature data on the stellar mass, radius, rotation period, and disk accretion rate to predict the field strength that should be present on each of our stars according to these magnetospheric accretion models. We show that our measured field values do not correlate with the field strengths predicted by simple magnetospheric accretion theory. We also use our field strength measurements and literature X-ray luminosity data to test a recent relationship expressing X-ray luminosity as a function of surface magnetic flux derived from various solar feature and main sequence star measurements. We find that the T Tauri stars we have observed have weaker than expected X-ray emission by over an order of magnitude on average using this relationship. We suggest the cause for this is actually a result of the very strong fields on these stars which decreases the efficiency with which gas motions in the photosphere can tangle magnetic flux tubes in the corona.Comment: 25 pages, 5 figure

show abstract

“…Strong polarization signals in He I 5876 Å and other accretion related emission lines have now been reported on a number of accreting T Tauri stars [50,52,54,57,235,243,251,252,265]. However, polarization measurements made using magnetically sensitive photospheric absorption lines, which presumably form uniformly across the entire stellar surface, yield small longitudinal field strengths, well below the average fields obtained from Zeeman broadening measurements [42,[234][235][236]. Commonly the net polarization signal is zero [252].…”

Section: Accreting T Tauri Stars and Observations Of Their Magnetic F...mentioning

confidence: 99%

The magnetic fields of forming solar-like stars

Gregory¹,

Jardine²,

Gray³

et al. 2010

Rep. Prog. Phys.

View full text Add to dashboard Cite

Magnetic fields play a crucial role at all stages of the formation of low-mass stars and planetary systems. In the final stages, in particular, they control the kinematics of in-falling gas from circumstellar discs, and the launching and collimation of spectacular outflows. The magnetic coupling with the disc is thought to influence the rotational evolution of the star, while magnetized stellar winds control the braking of more evolved stars and may influence the migration of planets. Magnetic reconnection events trigger energetic flares which irradiate circumstellar discs with high energy particles that influence the disc chemistry and set the initial conditions for planet formation. However, it is only in the past few years that the current generation of optical spectropolarimeters has allowed the magnetic fields of forming solar-like stars to be probed in unprecedented detail. In order to do justice to the recent extensive observational programs new theoretical models are being developed that incorporate magnetic fields with an observed degree of complexity. In this review we draw together disparate results from the classical electromagnetism, molecular physics/chemistry and the geophysics literature, and demonstrate how they can be adapted to construct models of the large scale magnetospheres of stars and planets. We conclude by examining how the incorporation of multipolar magnetic fields into new theoretical models will drive future progress in the field through the elucidation of several observational conundrums.(Some figures in this article are in colour only in the electronic version) 3.4. Difference between a spherical and Cartesian tensor approach 13 4. Magnetospheric accretion models with multipolar magnetic fields 14 4.1. Development of PFSS models and comparison with MHD field extrapolations 14 4.2. Potential field models of T Tauri magnetospheres with complex fields 16 4.3. 3D MHD models of T Tauri magnetospheres with non-dipolar fields 18 5. Summary and applications to outstanding problems 19 Acknowledgments 21 Appendix A. Relations between the equatorial and polar field strength for a multipole of arbitrary order l 21 Appendix A.1. Odd-order multipoles 21 Appendix A.2. Even-order multipoles 22 Appendix B. Electrostatic expansion using Cartesian tensors 22 Appendix B.1. The dipole term 23 Appendix B.2. The quadrupole term 23 References 24

show abstract

Analysis of magnetic field measurements for T Tau

Cited by 4 publications

References 6 publications

Magnetospheric accretion in T Tauri stars

Magnetospheric accretion in T Tauri stars

The Magnetic Fields of Classical T Tauri Stars

The magnetic fields of forming solar-like stars

Contact Info

Product

Resources

About