Spinor: Visible and Infrared Spectro-Polarimetry at the National Solar Observatory

Socas‐Navarro, H.; Elmore, D.; Pietarila, A.; Darnell, Anthony; Lites, B. W.; Tomczyk, S.; Hegwer, S.

doi:10.1007/s11207-006-0020-x

Cited by 92 publications

(71 citation statements)

References 26 publications

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“…From the 1960's and up through the mid-1980's it was occasionally employed, in particular in multi-line spectrographic studies (among others, Pasachoff et al 1968;Linsky et al 1970;Mein 1971;Shine & Linsky 1972;Beckers et al 1972;Shine & Linsky 1974;Lites 1984). Spurred by the availability of CCD detectors with high sensitivity in this wavelength range, the last decade has instead seen a rapid growth of observational studies adopting these lines both for solar and cool star research; we refer the reader to Socas-Navarro et al (2006); Uitenbroek (2006b); Tziotziou et al (2006); Uitenbroek et al (2006); Pietarila et al (2007b) for recent examples of solar studies, and to Chmielewski (2000); Andretta et al (2005) for the stellar case.…”

Section: Introductionmentioning

confidence: 99%

The solar chromosphere at high resolution with IBIS

Cauzzi¹,

Reardon²,

Uitenbroek

et al. 2008

A&A

157

135

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Context. The chromosphere remains a poorly understood part of the solar atmosphere, as current modeling and observing capabilities are still ill-suited to investigate in depth its fully 3-dimensional nature. In particular, chromospheric observations that can preserve high spatial and temporal resolution while providing spectral information over extended fields of view are still very scarce. Aims. In this paper, we seek to establish the suitability of imaging spectroscopy performed in the Ca II 854.2 nm line as a means to investigate the solar chromosphere at high resolution. Methods. We utilize monochromatic images obtained with the Interferometric BIdimensional Spectrometer (IBIS) at multiple wavelengths within the Ca II 854.2 nm line and over several quiet areas. We analyze both the morphological properties derived from narrow-band monochromatic images and the average spectral properties of distinct solar features such as network points, internetwork areas and fibrils. Results. The spectral properties derived over quiet-Sun targets are in full agreement with earlier results obtained with fixed-slit spectrographic observations, highlighting the reliability of the spectral information obtained with IBIS. Furthermore, the very narrowband IBIS imaging reveals with much clarity the dual nature of the Ca II 854.2 nm line: its outer wings gradually sample the solar photosphere, while the core is a purely chromospheric indicator. The latter displays a wealth of fine structures including bright points, akin to the Ca II H 2V and K 2V grains, as well as fibrils originating from even the smallest magnetic elements. The fibrils occupy a large fraction of the observed field of view even in the quiet regions, and clearly outline atmospheric volumes with different dynamical properties, strongly dependent on the local magnetic topology. This highlights the fact that 1-D models stratified along the vertical direction can provide only a very limited representation of the actual chromospheric physics. Conclusions. Imaging spectroscopy in the Ca II 854.2 nm line currently represents one of the best observational tools to investigate the highly structured and highly dynamical chromospheric environment. A high performance instrument such as IBIS is crucial in order to achieve the necessary spectral purity and stability, spatial resolution, and temporal cadence.

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Section: Introductionmentioning

confidence: 99%

The solar chromosphere at high resolution with IBIS

Cauzzi¹,

Reardon²,

Uitenbroek

et al. 2008

A&A

157

135

View full text Add to dashboard Cite

show abstract

“…Indeed, in recent years, the use of the infrared triplet for solar studies has increased notably (see, e.g. Socas-Navarro et al 2006;Uitenbroek 2006b;Tziotziou et al 2006), although studies combining spatial and spectral high resolution over extended fields of view (FOV) are still scarce.…”

Section: Introductionmentioning

confidence: 99%

The solar chromosphere at high resolution with IBIS

Reardon

Uitenbroek

Cauzzi

2009

A&A

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Aims. Filtergrams obtained in Ca II H, Ca II K, and Hα are often employed as diagnostics of the solar chromosphere. The vastly disparate appearance between the typical filtergrams in these different lines calls into question the nature of what is actually being observed. We investigate the lack of obvious structures of magnetic origin such as fibrils and mottles in on-disk Ca II H and K images. Methods. We directly compare a temporal sequence of classical Ca II K filtergrams with a co-spatial and co-temporal sequence of spectrally resolved Ca II 854.2 images obtained with the Interferometric Bidimensional Spectrometer (IBIS), considering the effect of both the spectral and spatial smearing. We analyze the temporal behavior of the two series by means of Fourier analysis.Results. The lack of fine magnetic structuring in Ca II K filtergrams, even with the narrowest available filters, is due to observational effects, primarily contributions from the bright, photospheric wings of the line that swamp the small and dark chromospheric structures. Signatures of fibrils remain, however, in the temporal evolution of the filtergrams, in particular with the evidence of magnetic shadows around the network elements. The Ca II K filtergrams do not appear, however, to properly reflect the high-frequency behavior of the chromosphere. Using the same analysis, we find no significant chromospheric signature in the Hinode/SOT Ca II H quiet-Sun filtergrams.Conclusions. The picture provided by Hα and Ca II 854.2, which show significant portions of the chromosphere dominated by magnetic structuring, appears to reflect the true and essential nature of the solar chromosphere. Data that do not resolve this aspect, whether spatially or spectrally, may misrepresent the behavior the chromosphere.

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“…Simultaneous photospheric and chromospheric magnetic field measurements (Socas-Navarro, 2005) performed with instruments such as the SPINOR (Spectropolarimeter for Infrared and Optical Regions) (Elmore et al, 2005;Socas-Navarro et al, 2006) that provide crucial information about the 3-D structure Solar Astronomy at High Altitude 819 of the magnetic field. NLST backend instruments will also be designed in a similar fashion for multiline polarimetry at visible and infrared wavelengths.…”

Section: High Altitude Advantages For Infrared and Uv Observationsmentioning

confidence: 99%

Solar Astronomy at High Altitude

Hasan¹,

Bagare²,

Rangarajan³

2014

Proceedings of the Indian National Science Academy

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A major project called the National Large Solar Telescope (NLST) has been proposed for pursuing Solar Astronomy at High Altitude. The project envisages the development of a state-of-the-art 2-m class telescope to carry out high-resolution studies of the solar atmosphere. This project is led by the Indian Institute of Astrophysics and has national and international partners. Its geographical location will fill the longitudinal gap between Japan and Europe and is expected to be the largest solar telescope with an aperture larger than 1.5 m till ATST and EST come into operation. NLST is an on-axis alt-azimuth Gregorian multi-purpose open telescope with the provision of carrying out nighttime stellar observations using a spectrograph at the Nasmyth focus. The telescope utilizes an innovative design with low number of reflections to achieve a high throughput and low polarization. High order adaptive optics is integrated into the design that works with a modest Frieds parameter of 7-cm to give diffraction limited performance. The telescope will be equipped with a suite of post-focus instruments including broad and narrow band imagers, a high-resolution spectrograph and a polarimeter. A comprehensive site characterization programme has demonstrated the presence of at least two excellent sites for setting up observational facilities for solar astronomy at high altitude in India.

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Spinor: Visible and Infrared Spectro-Polarimetry at the National Solar Observatory

Cited by 92 publications

References 26 publications

The solar chromosphere at high resolution with IBIS

The solar chromosphere at high resolution with IBIS

The solar chromosphere at high resolution with IBIS

Solar Astronomy at High Altitude

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