Imaging spectropolarimetry of Ti I 2231 nm in a sunspot

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	Imaging spectropolarimetry of Ti I 2231 nm in a sunspot
	Penn, MJ 1,2; Cao WD(曹文达)3,4 ; Walton, SR 2; Chapman, GA 1; Livingston, W 1
刊名	SOLAR PHYSICS
	2003-07
卷号	215 期号:1 页码:87-97
ISSN号	0038-0938
通讯作者	Penn, MJ (reprint author), Natl Opt Astron Observ, Natl Solar Observ, 950 N Cherry Ave, Tucson, AZ 85719 USA.
产权排序	第三完成单位
英文摘要	Spectro-polarimetric observations at 2231 nm were made of NOAA 10008 near the west solar limb on 29 June 2002 using the National Solar Observatory McMath-Pierce Telescope at Kitt Peak and the California State University Northridge - National Solar Observatory infrared camera. Scans of spectra in both Stokes I and Stokes V were collected; the intensity spectra were processed to remove strong telluric absorption lines, and the Stokes V umbral spectra were corrected for instrumental polarization. The sunspot temperature is computed using the continuum contrast and umbral temperatures down to about 3700 K are observed. A strong Ti I line at 2231.0 nm is used to probe the magnetic and velocity fields in the spot umbra and penumbra. Measurements of the Ti I equivalent width versus plasma temperature in the sunspot agree with model predictions. Zeeman splitting measurements of the Stokes I and Stokes V profiles show magnetic fields up to 3300 G in the umbra, and a dependence of the magnetic field on the plasma temperature similar to that which was seen using Fe I 1565 nm observations of the same spot two days earlier. The umbral Doppler velocity measurements are averaged in 16 azimuthal bins, and no radial flows are revealed to a limit of +/- 200 m s(-1). A Stokes V magnetogram shows a reversal of the line-of-sight magnetic component between the limb and disk center sides of the penumbra. Because the Ti I line is weak in the penumbra, individual spectra are averaged in azimuthal bins over the entire penumbral radial extent. The averaged Stokes V spectra show a magnetic reversal as a function of sunspot azimuthal angle. The mean penumbral magnetic field as measured with the Stokes V Zeeman component splitting is 1400 G. Several weak spectral lines are observed in the sunspot and the variation of the equivalent width versus temperature for four lines is examined. If these lines are from molecules, it is possible that lines at 2230.67, 2230.77, and 2231.70 nm originate from OH, while the line at 2232.21 nm may originate from CN.
学科主题	Astronomy & Astrophysics
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	SOLAR MAGNETIC FEATURES ; INFRARED LINES ; TEMPERATURE ; PROBES ; FIELD ; COOL
收录类别	SCI
原文出处	http://link.springer.com/article/10.1023%2FA%3A1024858706915
语种	英语
WOS记录号	WOS:000184251900006
内容类型	期刊论文
源URL	[http://ir.ynao.ac.cn/handle/114a53/4159]
专题	云南天文台_其他
作者单位	1.National Solar Observatory, 950 N Cherry Av, Tucson, AZ , 85719, U.S.A 2.Department of Physics and Astronomy, California State University Northridge, 18111 Nordhoff St, Northridge, CA, 91330-8268, U.S.A 3.National Astronomical Observatories, CAS, Yunnan Observatory, PO Box 110 4.Center for Solar Research, New Jersey Institute of Technology, 323 Martin Luther King Blvd, Newark, NJ, 07102, U.S.A
推荐引用方式 GB/T 7714	Penn, MJ,Cao WD,Walton, SR,et al. Imaging spectropolarimetry of Ti I 2231 nm in a sunspot[J]. SOLAR PHYSICS,2003,215(1):87-97.
APA	Penn, MJ,Cao WD,Walton, SR,Chapman, GA,&Livingston, W.(2003).Imaging spectropolarimetry of Ti I 2231 nm in a sunspot.SOLAR PHYSICS,215(1),87-97.
MLA	Penn, MJ,et al."Imaging spectropolarimetry of Ti I 2231 nm in a sunspot".SOLAR PHYSICS 215.1(2003):87-97.