Science Goals and Development of the Advanced Technology Solar Telescope

Keil, Stephen L.; Rimmelé, Thomas; Oschmann, Jacobus M.; Hubbard, Robert P.; Warner, Mark; Price, R.; Dalrymple, N.; Team, Atst

doi:10.1017/s1743921304006933

Cited by 9 publications

(4 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For a more sophisticated investigation, a much higher spatial resolution is required as will be provided by a new generation of telescopes like GREGOR (see Volkmer et al 2005) or the ATST (see Keil et al 2004). Several spectral lines sensitive to different heights should be observed simultaneously.…”

Section: Discussionmentioning

confidence: 99%

Vertical current densities and magnetic gradients in sunspots

Balthasar¹

2006

A&A

View full text Add to dashboard Cite

Aims. The vertical component of electric current densities and the height dependence of the vertical component of the magnetic field in sunspots were determined. Methods. Full-Stokes magnetograms of eight sunspots obtained from infrared spectro-polarimetric measurements were investigated. The magnetic field strength and the magnetic inclination and azimuth were obtained from an inversion code. Vertical current densities and the vertical derivative of the vertical component of the magnetic field strength resulted from Maxwell equations. Results. It is found that electric current densities and magnetic gradients depend on the finestructure of the sunspots. Typical values for current densities vary in the range ±40 mA m −2 , but their errors are of the same order. Disturbances in the radial structure of the penumbra are related to enhanced current densities up to 149 mA m −2 , and a maximum value of 166 mA m −2 was found in a light bridge. There are indications that the radial structure of the penumbra is related to current densities, but no correlation to the local intensity fluctuations was found in the outer penumbra. The vertical component of the magnetic field decreases by 0.5-1.5 G km −1 in the umbra. Mean values in the inner penumbra are somewhat smaller than in the umbra, and locally dark structures exhibit a faster decrease with height than bright ones. In the outer penumbra the vertical magnetic component increases, independent of the local intensity distribution. Conclusions. Electric current densities could be a diagnostic tool for understanding the penumbral finestructure, although the presently available spatial resolution is probably not good enough to avoid artifacts. Magnetic extrapolations might depend crucially on this problem.

show abstract

Section: Discussionmentioning

confidence: 99%

Vertical current densities and magnetic gradients in sunspots

Balthasar¹

2006

A&A

View full text Add to dashboard Cite

show abstract

“…They obtained full Stokes profiles of limb coronal fields and found that field strength is about 4 G at 100 in height above the photosphere. One of the main purposes of the Advanced Technology Solar Telescope (ATST) is to observe coronal magnetic fields (see Keil et al 2004 and their Web site 2 ).…”

Section: Introductionmentioning

confidence: 99%

Preprocessing Magnetic Fields With Chromospheric Longitudinal Fields

Yamamoto

Kusano

2012

ApJ

View full text Add to dashboard Cite

Nonlinear force-free field (NLFFF) extrapolation is a powerful tool for the modeling of the magnetic field in the solar corona. However, since the photospheric magnetic field does not in general satisfy the force-free condition, some kind of processing is required to assimilate data into the model. In this paper, we report the results of new preprocessing for the NLFFF extrapolation. Through this preprocessing, we expect to obtain magnetic field data similar to those in the chromosphere. In our preprocessing, we add a new term concerning chromospheric longitudinal fields into the optimization function proposed by Wiegelmann et al. We perform a parameter survey of six free parameters to find minimum force-and torque-freeness with the simulated-annealing method. Analyzed data are a photospheric vector magnetogram of AR 10953 observed with the Hinode spectropolarimeter and a chromospheric longitudinal magnetogram observed with SOLIS spectropolarimeter. It is found that some preprocessed fields show the smallest force-and torque-freeness and are very similar to the chromospheric longitudinal fields. On the other hand, other preprocessed fields show noisy maps, although the force-and torque-freeness are of the same order. By analyzing preprocessed noisy maps in the wave number space, we found that small and large wave number components balance out on the force-free index. We also discuss our iteration limit of the simulated-annealing method and magnetic structure broadening in the chromosphere.

show abstract

“…目前国际上 1 m以上的太阳望远镜共有4架, 包括美国大熊湖天文台1.6 m太阳望远镜(GST) [8] 、位于加那利群岛的德国1.5 m太阳望远镜(GREGOR)、瑞典1 m太阳望远镜(SST) [9] 和我国的1 m真空太阳望远镜(NVST). 正在建设中的大望远镜有美国国立天文台4 m太阳望远镜(DKIST) [10] . 规划中的大望远镜包括: 欧洲的4 m太阳望远镜(EST) 1) 和印度的2 m太阳望远镜(NLST) [11] .…”

Section: 国内外同类观测设备的研究现状和发展趋势unclassified