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Title: Dynamics of Subarcsecond Bright Dots in the Transition Region above Sunspots and Their Relation to Penumbral Micro-jets

Abstract

Recent high-resolution observations have revealed that subarcsecond bright dots (BDs) with sub-minute lifetimes appear ubiquitously in the transition region (TR) above sunspot penumbra. The presence of penumbral micro-jets (PMJs) in the chromosphere was previously reported. It was proposed that both the PMJs and BDs are formed due to a magnetic reconnection process and may play an important role in heating of the penumbra. Using simultaneous observations of the chromosphere from the Solar Optical Telescope (SOT) on board Hinode and observations of the TR from the Interface Region Imaging Spectrograph , we study the dynamics of BDs and their relation to PMJs. We find two types of BDs, one that is related to PMJs, and another that does not show any visible dynamics in the SOT Ca ii H images. From a statistical analysis we show that these two types have different properties. The BDs that are related to PMJs always appear at the top of the PMJs, the vast majority of which show inward motion and originate before the generation of the PMJs. These results may indicate that the reconnection occurs at the lower coronal/TR height and initiates PMJs at the chromosphere. This formation mechanism is in contrast with themore » formation of PMJs by reconnection in the (upper) photosphere between differently inclined fields.« less

Authors:
;  [1];  [2];  [3]
  1. Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India)
  2. School of Earth and Space Sciences, Peking University (China)
  3. University of St. Andrews, St. Andrews (United Kingdom)
Publication Date:
OSTI Identifier:
22654553
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 835; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CHROMOSPHERE; INTERFACES; LIFETIME; MAGNETIC FIELDS; MAGNETIC RECONNECTION; OSCILLATIONS; PHOTOSPHERE; RESOLUTION; SUN; TELESCOPES; ULTRAVIOLET RADIATION

Citation Formats

Samanta, Tanmoy, Banerjee, Dipankar, Tian, Hui, and Schanche, Nicole, E-mail: tsamanta@iiap.res.in, E-mail: huitian@pku.edu.cn, E-mail: dipu@iiap.res.in, E-mail: ns81@st-andrews.ac.uk. Dynamics of Subarcsecond Bright Dots in the Transition Region above Sunspots and Their Relation to Penumbral Micro-jets. United States: N. p., 2017. Web. doi:10.3847/2041-8213/835/2/L19.
Samanta, Tanmoy, Banerjee, Dipankar, Tian, Hui, & Schanche, Nicole, E-mail: tsamanta@iiap.res.in, E-mail: huitian@pku.edu.cn, E-mail: dipu@iiap.res.in, E-mail: ns81@st-andrews.ac.uk. Dynamics of Subarcsecond Bright Dots in the Transition Region above Sunspots and Their Relation to Penumbral Micro-jets. United States. doi:10.3847/2041-8213/835/2/L19.
Samanta, Tanmoy, Banerjee, Dipankar, Tian, Hui, and Schanche, Nicole, E-mail: tsamanta@iiap.res.in, E-mail: huitian@pku.edu.cn, E-mail: dipu@iiap.res.in, E-mail: ns81@st-andrews.ac.uk. Wed . "Dynamics of Subarcsecond Bright Dots in the Transition Region above Sunspots and Their Relation to Penumbral Micro-jets". United States. doi:10.3847/2041-8213/835/2/L19.
@article{osti_22654553,
title = {Dynamics of Subarcsecond Bright Dots in the Transition Region above Sunspots and Their Relation to Penumbral Micro-jets},
author = {Samanta, Tanmoy and Banerjee, Dipankar and Tian, Hui and Schanche, Nicole, E-mail: tsamanta@iiap.res.in, E-mail: huitian@pku.edu.cn, E-mail: dipu@iiap.res.in, E-mail: ns81@st-andrews.ac.uk},
abstractNote = {Recent high-resolution observations have revealed that subarcsecond bright dots (BDs) with sub-minute lifetimes appear ubiquitously in the transition region (TR) above sunspot penumbra. The presence of penumbral micro-jets (PMJs) in the chromosphere was previously reported. It was proposed that both the PMJs and BDs are formed due to a magnetic reconnection process and may play an important role in heating of the penumbra. Using simultaneous observations of the chromosphere from the Solar Optical Telescope (SOT) on board Hinode and observations of the TR from the Interface Region Imaging Spectrograph , we study the dynamics of BDs and their relation to PMJs. We find two types of BDs, one that is related to PMJs, and another that does not show any visible dynamics in the SOT Ca ii H images. From a statistical analysis we show that these two types have different properties. The BDs that are related to PMJs always appear at the top of the PMJs, the vast majority of which show inward motion and originate before the generation of the PMJs. These results may indicate that the reconnection occurs at the lower coronal/TR height and initiates PMJs at the chromosphere. This formation mechanism is in contrast with the formation of PMJs by reconnection in the (upper) photosphere between differently inclined fields.},
doi = {10.3847/2041-8213/835/2/L19},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 835,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}