Examining the Magnetic Field Strength and the Horizontal and Vertical Motions in an Emerging Active Region
详细信息 查看全文
- 作者：Chia-Hsien Lin ; Yu-Che Chen
- 关键词：Active regions ; magnetic fields ; Active regions ; models ; Active regions ; structure ; Active regions ; velocity field
- 刊名：Solar Physics
- 出版年：2016
- 出版时间：March 2016
- 年：2016
- 卷：291
- 期：3
- 页码：751-777
- 全文大小：8,232 KB
- 参考文献：Brandenburg, A., Kemel, K., Kleeorin, N., Mitra, D., Rogachevskii, I.: 2011, Detection of negative effective magnetic pressure instability in turbulence simulations. Astrophys. J. Lett. 740, L50. DOI . ADS . ADS CrossRef
Calabretta, M.R., Greisen, E.W.: 2002, Representations of celestial coordinates in FITS. Astron. Astrophys. 395, 1077. DOI . ADS . ADS CrossRef
Caligari, P., Moreno-Insertis, F., Schüssler, M.: 1995, Emerging flux tubes in the solar convection zone. 1: Asymmetry, tilt, and emergence latitude. Astrophys. J. 441, 886. DOI . ADS . ADS CrossRef
Centeno, R.: 2012, The naked emergence of solar active regions observed with SDO/HMI. Astrophys. J. 759, 72. DOI . ADS . ADS CrossRef
Cheung, M.C.M., Isobe, H.: 2014, Flux emergence (theory). Living Rev. Solar Phys. 11, 3. DOI . ADS . ADS CrossRef
Chintzoglou, G., Zhang, J.: 2013, Reconstructing the subsurface three-dimensional magnetic structure of a solar active region using SDO/HMI observations. Astrophys. J. Lett. 764, L3. DOI . ADS . ADS CrossRef
Chou, D.-Y.: 1993, Structure of emerging flux regions. In: Zirin, H., Ai, G., Wang, H. (eds.) IAU Colloq. 141: The Magnetic and Velocity Fields of Solar Active Regions, Astron. Soc. Pacific C. S. 46, 471. ADS .
Chou, D.-Y., Fisher, G.H.: 1989, Dynamics of anchored flux tubes in the convection zone. I – Details of the model. Astrophys. J. 341, 533. DOI . ADS . ADS CrossRef
Chou, D.-Y., Wang, H.: 1987, The separation velocity of emerging magnetic flux. Solar Phys. 110, 81. DOI . ADS . ADS CrossRef
Fan, Y.: 2004, Dynamics of emerging flux tubes. In: Sakurai, T., Sekii, T. (eds.) The Solar-B Mission and the Forefront of Solar Physics, Astron. Soc. Pacific C. S. 325, 47. ADS .
Fan, Y.: 2008, The three-dimensional evolution of buoyant magnetic flux tubes in a model solar convective envelope. Astrophys. J. 676, 680. DOI . ADS . ADS CrossRef
Harvey, K.L., Martin, S.F.: 1973, Ephemeral active regions. Solar Phys. 32, 389. DOI . ADS . ADS CrossRef
Hoeksema, J.T., Liu, Y., Hayashi, K., Sun, X., Schou, J., Couvidat, S., Norton, A., Bobra, M., Centeno, R., Leka, K.D., Barnes, G., Turmon, M.: 2014, The Helioseismic and Magnetic Imager (HMI) vector magnetic field pipeline: Overview and performance. Solar Phys. 289, 3483. DOI . ADS . ADS CrossRef
Kubo, M., Shimizu, T., Lites, B.W.: 2003, The evolution of vector magnetic fields in an emerging flux region. Astrophys. J. 595, 465. DOI . ADS . ADS CrossRef
Leka, K.D., Canfield, R.C., McClymont, A.N., van Driel-Gesztelyi, L.: 1996, Evidence for current-carrying emerging flux. Astrophys. J. 462, 547. DOI . ADS . ADS CrossRef
Lites, B.W., Skumanich, A., Martinez Pillet, V.: 1998, Vector magnetic fields of emerging solar flux. I. Properties at the site of emergence. Astron. Astrophys. 333, 1053. ADS . ADS
Metcalf, T.R.: 1994, Resolving the 180-degree ambiguity in vector magnetic field measurements: The ‘minimum’ energy solution. Solar Phys. 155, 235. DOI . ADS . ADS CrossRef
Parker, E.N.: 1955, The formation of sunspots from the solar toroidal field. Astrophys. J. 121, 491. DOI . ADS . ADS CrossRef
Parker, E.N.: 1978, Hydraulic concentration of magnetic fields in the solar photosphere. VI – Adiabatic cooling and concentration in downdrafts. Astrophys. J. 221, 368. DOI . ADS . ADS CrossRef
Pesnell, W.D., Thompson, B.J., Chamberlin, P.C.: 2012, The Solar Dynamics Observatory (SDO). Solar Phys. 275, 3. DOI . ADS . ADS CrossRef
Rempel, M.: 2011, Subsurface magnetic field and flow structure of simulated sunspots. Astrophys. J. 740, 15. DOI . ADS . ADS CrossRef
Rempel, M., Cheung, M.C.M.: 2014, Numerical simulations of active region scale flux emergence: From spot formation to decay. Astrophys. J. 785, 90. DOI . ADS . ADS CrossRef
Schou, J., Scherrer, P.H., Bush, R.I., Wachter, R., Couvidat, S., Rabello-Soares, M.C., Bogart, R.S., Hoeksema, J.T., Liu, Y., Duvall, T.L., Akin, D.J., Allard, B.A., Miles, J.W., Rairden, R., Shine, R.A., Tarbell, T.D., Title, A.M., Wolfson, C.J., Elmore, D.F., Norton, A.A., Tomczyk, S.: 2012, Design and ground calibration of the Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory (SDO). Solar Phys. 275, 229. DOI . ADS . ADS CrossRef
Schüssler, M.: 1979, Magnetic buoyancy revisited – Analytical and numerical results for rising flux tubes. Astron. Astrophys. 71, 79. ADS . ADS
Shimizu, T., Shine, R.A., Title, A.M., Tarbell, T.D., Frank, Z.: 2002, Photospheric magnetic activities responsible for soft X-ray pointlike microflares. I. Identifications of associated photospheric/chromospheric activities. Astrophys. J. 574, 1074. DOI . ADS . ADS CrossRef
Strous, L.H., Scharmer, G., Tarbell, T.D., Title, A.M., Zwaan, C.: 1996, Phenomena in an emerging active region. I. Horizontal dynamics. Astron. Astrophys. 306, 947. ADS . ADS
Sun, X.: 2013, On the coordinate System of Space-Weather HMI Active Region Patches (SHARPs): A technical note. ArXiv e-prints. arXiv .
Tanaka, K.: 1991, Studies on a very flare-active delta group – Peculiar delta spot evolution and inferred subsurface magnetic rope structure. Solar Phys. 136, 133. DOI . ADS . ADS CrossRef
Weber, M.A., Fan, Y., Miesch, M.S.: 2011, The rise of active region flux tubes in the turbulent solar convective envelope. Astrophys. J. 741, 11. DOI . ADS . ADS CrossRef - 作者单位：Chia-Hsien Lin (1)
Yu-Che Chen (2)
1. Graduate Institute of Space Science, National Central University, Chung-Li, Taoyuan, Taiwan
2. Department of Atmospheric Science, National Central University, Chung-Li, Taoyuan, Taiwan - 刊物类别：Physics and Astronomy
- 刊物主题：Physics
Astronomy
Extraterrestrial Physics and Space Sciences
Astrophysics - 出版者：Springer Netherlands
- ISSN：1573-093X
文摘
Earlier observational studies have used the time evolution of emerging magnetic flux regions at the photosphere to infer their subsurface structures, assuming that the flux structure does not change significantly over the near-surface layer. In this study, we test the validity of this assumption by comparing the horizontal and vertical motions of an emerging active region. The two motions would be correlated if the emerging structure is rigid. The selected active region (AR) NOAA 11645 is not embedded in detectable preexisting magnetic field. The observed horizontal motion is quantified by the separation of the two AR polarities and the width of the region. The vertical motion is derived from the magnetic buoyancy theory. Our results show that the separation of the polarities is fastest at the beginning with a velocity of \({\approx\,}4~\mbox{Mm}\,\mbox{hr}^{-1}\) and decreases to \({\le\,}1~\mbox{Mm}\,\mbox{hr}^{-1}\) after the main growing phase of flux emergence. The derived thick flux-tube buoyant velocity is between 1 and \(3~\mbox{Mm}\,\mbox{hr}^{-1}\), while the thin flux-tube approximation results in an unreasonably high buoyant velocity, consistent with the expectation that the approximation is inappropriate at the surface layer. The observed horizontal motion is not found to directly correlate with either the magnetic field strength or the derived buoyant velocities. However, the percentage of the horizontally oriented fields and the temporal derivatives of the field strength and the buoyant velocity show some positive correlations with the separation velocity. The results of this study imply that the assumption that the emerging active region is the cross section of a rising flux tube whose structure can be considered rigid as it rises through the near-surface layer should be taken with caution.