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Observations from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) reveal ubiquitous episodic outflows (jets) with an average speed around 120 km s-1 at temperatures often exceeding a million degree in…

Solar and Stellar Astrophysics · Physics 2011-07-27 Hui Tian , Scott W. McIntosh , Shadia Rifal Habbal , Jiansen He

Recent EUV spectroscopic observations indicate that slow magnetosonic waves are present in active region (AR) loops. Some of the spectral data were also interpreted as evidence of fast (~100-300 km/s) quasi-periodic flows. We have performed…

Solar and Stellar Astrophysics · Physics 2015-06-05 Leon Ofman , Tongjiang Wang , Joseph M. Davila

Recent observations from the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode have shown that low density areas on the periphery of active regions are characterized by strong blue-shifts at 1 MK. These Doppler shifts have been…

Solar and Stellar Astrophysics · Physics 2015-05-19 Ignacio Ugarte-Urra , Harry P. Warren

Quasi-periodic disturbances have been observed in the outer solar atmosphere for many years now. Although first interpreted as upflows (Schrijver et al. (1999)), they have been widely regarded as slow magnetoacoustic waves, due to observed…

Solar and Stellar Astrophysics · Physics 2015-06-05 G. Kiddie , I. De Moortel , G. Del Zanna , S. W. McIntosh , I. Whittaker

I report on observations of a set of magnetic loops above a region with late-phase flux emergence taken by IRIS, Hinode and SDO. The loop system consists of many transition region loop threads with size of 5--12\arcsec\ in length and…

Solar and Stellar Astrophysics · Physics 2019-01-09 Zhenghua Huang

Using UV spectra and SJIs from the IRIS, and coronal images and magnetograms from the Solar Dynamics Observatory (SDO), we present the new features in a quiescent filament channel: subarcsecond bright points (BPs) and quasi-periodic…

Solar and Stellar Astrophysics · Physics 2016-04-27 Ting Li , Jun Zhang

Spicules are the thin hair/grass-like structures that are prominently observed at the chromospheric solar limb. It is believed that fibrils and rapid blueshifted and redshifted excursions (RBEs and RREs; collectively referred to as REs)…

Solar and Stellar Astrophysics · Physics 2024-08-09 Ravi Chaurasiya , Ankala Raja Bayanna , R. E. Louis , T. M. D. Pereira , S. K. Mathew

We report multi-wavelength ultraviolet observations taken with the IRIS satellite, concerning the emergence phase in the upper chromosphere and transition region of an emerging flux region (EFR) embedded in the pre-existing field of active…

Solar and Stellar Astrophysics · Physics 2018-04-18 Salvo L. Guglielmino , Francesca Zuccarello , Peter R. Young , Mariariata Murabito , Paolo Romano

We study the high frequency dynamics in the braided magnetic structure of an active region (AR 11520) moss as observed by High-Resolution Coronal Imager (Hi-C). We detect quasi periodic flows and waves in these structures. We search for…

Solar and Stellar Astrophysics · Physics 2015-06-23 V Pant , A Datta , Dipankar Banerjee

Nanoflares are regarded as one of the major mechanisms of magnetic energy release and coronal heating in the solar outer atmosphere. We conduct a statistical study on the response of the chromosphere and transition region to nanoflares, as…

Solar and Stellar Astrophysics · Physics 2023-03-29 Kyuhyoun Cho , Paola Testa , Bart De Pontieu , Vanessa Polito

Using one-arcsecond-slit scan observations from the Hinode/EUV Imaging Spectrometer (EIS) on 05 February 2007, we find the plasma outflows in the open and expanding coronal funnels at the eastern boundary of AR 10940. The Doppler velocity…

Solar and Stellar Astrophysics · Physics 2015-06-22 A. K. Srivastava , P. Konkol , K. Murawski , B. N. Dwivedi , A. Mohan

We examine the role of small-scale transients in the formation and evolution of solar coronal plumes. We study the dynamics of plume footpoints seen in the vicinity of a coronal hole using the Atmospheric Imaging Assembly (AIA) images, the…

Solar and Stellar Astrophysics · Physics 2015-05-19 Vaibhav Pant , Laurent Dolla , Rakesh Mazumder , Dipankar Banerjee , S. Krishna Prasad , Vemareddy Panditi

Using high-resolution ring analysis (HRRA) we deduce subsurface flows within magnetic active regions and within quiet sun. With this procedure we are capable of measuring flows with a horizontal spatial resolution of 2 degrees in…

Solar and Stellar Astrophysics · Physics 2011-02-11 Bradley W. Hindman , Deborah A. Haber , Juri Toomre

Since the discovery of quasi-periodic propagating oscillations with periods of order three to ten minutes in coronal loops with TRACE and EIT (later with EUVI and EIS), they have been almost universally interpreted as evidence for…

Solar and Stellar Astrophysics · Physics 2015-05-19 Bart De Pontieu , Scott W. McIntosh

Solar ultraviolet (UV) bursts are small-scale compact brightenings in transition region images. The spectral profiles of transition region lines in these bursts are significantly enhanced and broadened, often with chromospheric absorption…

Solar and Stellar Astrophysics · Physics 2020-04-07 Yajie Chen , Hui Tian , Xiaoshuai Zhu , Tanmoy Samanta , Linghua Wang , Jiansen He

We report a spectroscopic analysis of an EIT wave event that occurred in active region 11081 on 2010 June 12 and was associated with an M2.0 class flare. The wave propagated near circularly. The south-eastern part of the wave front passed…

Solar and Stellar Astrophysics · Physics 2015-05-28 F. Chen , M. D. Ding , P. F. Chen , L. K. Harra

In this research, we investigate Explosive Events (EEs) in the off-limb solar atmosphere, with simultaneous observations from the Si IV, Mg II k, and slit-jaw images (SJI) of the Interface Region Imaging Spectrograph (IRIS), on 17 August…

Solar and Stellar Astrophysics · Physics 2022-07-06 E. Tavabi , S. Zeighami , M. Heydari

In the present paper, we use Si IV 1393.755 \AA\ spectral line observed by the Interface Region Imaging Spectrograph (IRIS) in the quiet-Sun to determine physical nature of the solar transition region (TR) oscillations. We analyze the…

Solar and Stellar Astrophysics · Physics 2022-10-12 Kartika Sangal , A. K. Srivastava , P. Kayshap , T. J Wang , J. J. González-Avilés , Abhinav Prasad

We study the dynamics of low-lying cool loop systems for three datasets as observed by the Interface Region Imaging Spectrograph (IRIS). Radiances, Doppler shifts and line widths are investigated in and around observed cool loop systems…

Solar and Stellar Astrophysics · Physics 2019-03-27 Yamini K. Rao , Abhishek K. Srivastava , Pradeep Kayshap , Klaus Wilhelm , Bhola N. Dwivedi

Super-sonic downflows have been observed in transition region spectra above numerous sunspots; however, little research has been conducted to date into how persistent these signatures are within sunspots on time-scales longer than a few…

Solar and Stellar Astrophysics · Physics 2020-04-15 C. J. Nelson , S. Krishna Prasad , M. Mathioudakis