AN INTERFACE REGION IMAGING SPECTROGRAPH FIRST VIEW ON SOLAR SPICULES

Journal Article · Mon Sep 01 00:00:00 EDT 2014 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/792/1/L15· OSTI ID:22365163

Pereira, T. M. D.; De Pontieu, B.; Carlsson, M.; Hansteen, V. ^[1]; Tarbell, T. D.; Lemen, J.; Title, A.; Boerner, P.; Hurlburt, N.; Wülser, J. P.; Martínez-Sykora, J.; Kleint, L. ^[2]; Golub, L.; McKillop, S.; Reeves, K. K.; Saar, S.; Testa, P.; Tian, H. ^[3]; Jaeggli, S.

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1. Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway)
2. Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street, Org. A021S, Bldg. 252, Palo Alto, CA 94304 (United States)
3. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

Solar spicules have eluded modelers and observers for decades. Since the discovery of the more energetic type II, spicules have become a heated topic but their contribution to the energy balance of the low solar atmosphere remains unknown. Here we give a first glimpse of what quiet-Sun spicules look like when observed with NASA's recently launched Interface Region Imaging Spectrograph (IRIS). Using IRIS spectra and filtergrams that sample the chromosphere and transition region, we compare the properties and evolution of spicules as observed in a coordinated campaign with Hinode and the Atmospheric Imaging Assembly. Our IRIS observations allow us to follow the thermal evolution of type II spicules and finally confirm that the fading of Ca II H spicules appears to be caused by rapid heating to higher temperatures. The IRIS spicules do not fade but continue evolving, reaching higher and falling back down after 500-800 s. Ca II H type II spicules are thus the initial stages of violent and hotter events that mostly remain invisible in Ca II H filtergrams. These events have very different properties from type I spicules, which show lower velocities and no fading from chromospheric passbands. The IRIS spectra of spicules show the same signature as their proposed disk counterparts, reinforcing earlier work. Spectroheliograms from spectral rasters also confirm that quiet-Sun spicules originate in bushes from the magnetic network. Our results suggest that type II spicules are indeed the site of vigorous heating (to at least transition region temperatures) along extensive parts of the upward moving spicular plasma.

• OSTI ID: 22365163
• Journal Information: Astrophysical Journal Letters, Vol. 792, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
CHROMOSPHERE
COMPARATIVE EVALUATIONS
EMISSION SPECTRA
INTERFACES
NASA
PLASMA
SOLAR PROMINENCES
STAR EVOLUTION
SUN
VELOCITY