ON-DISK COUNTERPARTS OF TYPE II SPICULES IN THE Ca ii 854.2 nm AND Hα LINES

By L. R. V. Voort, J. Leenaarts, Bart De Pontieu, M. Carlsson, G. Vissers. 2009

154 citations recorded by the source corpus.

Recently, a second type of spicules was discovered at the solar limb with the Solar Optical Telescope onboard the Japanese Hinode spacecraft. These previously unrecognized type II spicules are thin chromospheric jets that are shorter lived (10–60 s) and that show much higher apparent upward velocities (of order 50–100 km s−1) than the classical spicules. Since they have been implicated in providing hot plasma to coronal loops, their formation, evolution, and properties are important ingredients for a better understanding of the mass and energy balance of the low solar atmosphere. Here, we report on the discovery of the disk counterparts of type II spicules using spectral imaging data in the Ca ii 854.2 nm and Hα lines with the CRisp Imaging SpectroPolarimeter at the Swedish Solar Telescope in La Palma. We find rapid blueward excursions in the line profiles of both chromospheric lines that correspond to thin, jet-like features that show apparent velocities of order 50 km s−1. These blueward excursions seem to form a separate absorbing component with Doppler shifts of order 20 and 50 km s−1 for the Ca ii 854.2 nm and Hα line, respectively. We show that the appearance, lifetimes, longitudinal and transverse velocities, and occurrence rate of these rapid blue excursions on the disk are very similar to those of the type II spicules at the limb. A detailed study of the spectral line profiles in these events suggests that plasma is accelerated along the jet, and plasma is being heated throughout the short lifetime of the event.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/cf1ece641502efea9289637c5d97e45786cce75e

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In Astronomy and Astrophysics

1. J. Leenaarts
2. M. Carlsson
3. Bart De Pontieu
4. V. Hansteen
5. L. R. V. Voort
6. Y. Suematsu
7. G. Tsiropoula
8. K. Tziotziou

In Instrumentation

1. M. Carlsson
2. J. Leenaarts
3. Bart De Pontieu
4. R. Rutten
5. L. R. V. Voort

Citations in the corpus

• THE FORMATION OF THE Hα LINE IN THE SOLAR CHROMOSPHERE (2012, methodology): “For more details on the data processing, we refer to Rouppe van der Voort et al. (2009).”
• Solar Fine-Scale Structures. I. Spicules and Other Small-Scale, Jet-Like Events at the Chromospheric Level: Observations and Physical Parameters (2012, methodology): “Rouppe van der Voort et al. (2009) from spectral observations in the Hα and Ca ii H 8542 Å lines reported also that the disk counterparts of Type II spicules might be the RBEs based on the similarities on their appearance, lifetimes, longitudinal and transverse velocities and occurrence rate.”
• Multiwavelength Studies of MHD Waves in the Solar Chromosphere (2015, background): “The differing behaviour of the related chromospheric phenomena is highlighted in Rouppe van der Voort et al. (2009), who report higher velocities in Rapid Blue-shifted Events (RBEs) observed in Hα than in Ca II 8542 Å and suggest the larger opacity in Hα allows the sampling of higher layers.”
• UBIQUITOUS TORSIONAL MOTIONS IN TYPE II SPICULES (2012, methodology): “On the disk they appear as rapidly moving absorption features in the blue wings of chromospheric lines (Langangen et al. 2008; Rouppe van der Voort et al. 2009).”