E-Print Archive

There are 3897 abstracts currently viewable.


Search:

Advanced Search
Options
Main Page Add New E-Print Submitter
Information
Feedback
News Help/FAQ About Preferences
Manage Key Phrase
Notification
A Steady-state Supersonic Downflow in the Transition Region above a Sunspot Umbra  

Thomas Straus   Submitted: 2015-07-23 07:58

We investigate a small-scale (≈ 1.5 Mm along the slit), supersonic downflow of about 90 km s-1 in the transition region above the light-bridged sunspot umbra in AR 11836. The observations were obtained with the Interface Region Spectrograph (IRIS) on 2013 September 2, from 16:40 to 17:59 UT. The downflow shows up as red-shifted "satellite" lines of the Si IV and O IV transition region lines and is remarkably steady over the observing period of nearly 80 min. The downflow is not visible in the chromospheric lines, which only show an intensity enhancement at the location of the downflow. The density inferred from the line ratio of the red-shifted satellites of the O IV lines (Ne = 1010.6±0.25 cm-3) is only a factor 2 smaller than the one inferred from the main components (Ne = 1010.95±0.20 cm-3). Consequently, this implies a substantial mass flux (≈ 5 x 10-7 g cm-2 s-1), which would evacuate the overlying corona on time scales of the order of 10 s. We interpret these findings as evidence of a stationary termination shock of a supersonic siphon flow in a cool loop rooted in the central umbra of the spot.

Authors: Thomas Straus and Bernhard Fleck and Vincenzo Andretta
Projects: IRIS

Publication Status: Accepted for A&A
Last Modified: 2015-07-23 10:11
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 


Key
Go to main E-Print pageGo to main E-Print page.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
Delete AbstractDelete abstract.

Abstracts by Author
A Steady-state Supersonic Downflow in the Transition Region above a Sunspot Umbra

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

Archive Maintainer
Alisdair Davey



© 2003 Solar Physics Group - Montana State University