Bibliographic Details
| Title: |
Center-to-limb Variation of Transition-region Doppler Shifts in Active Regions |
| Authors: |
Abhishek Rajhans, Durgesh Tripathi, Vinay L. Kashyap, James A. Klimchuk, Avyarthana Ghosh |
| Source: |
The Astrophysical Journal, Vol 944, Iss 2, p 158 (2023) |
| Publisher Information: |
IOP Publishing, 2023. |
| Publication Year: |
2023 |
| Collection: |
LCC:Astrophysics |
| Subject Terms: |
The Sun, Solar active regions, Solar activity, Sunspots, Solar physics, Solar photosphere, Astrophysics, QB460-466 |
| More Details: |
Studying Doppler shifts provides deep insights into the flow of mass and energy in the solar atmosphere. We perform a comprehensive measurement of Doppler shifts in the transition region and its center-to-limb variation (CLV) in the strong-field regions (∣ B ∣ ≥ 50 G) of 50 active regions (ARs), using the Si iv 1394 Å line recorded by the Interface Region Imaging Spectrometer. To locate the ARs and identify strong-field regions, we have used the magnetograms obtained by the Helioseismic and Magnetic Imager (HMI). We find that in strong-field regions, on average, all the ARs show a mean redshift ranging between 4 and 11 km s ^−1 , which varies with ARs. These flows show a mild CLV, with sizable magnitudes at the limb and substantial scatter in the mid-longitude range. Our observations do not support the idea that redshifts in the lower transition region ( T ≲ 0.1 MK) are produced by field-aligned downflows as a result of impulsive heating and they warrant an alternative interpretation, such as a downflow of type-II spicules in the presence of a chromospheric wall created by cooler type-I spicules. |
| Document Type: |
article |
| File Description: |
electronic resource |
| Language: |
English |
| ISSN: |
1538-4357 |
| Relation: |
https://doaj.org/toc/1538-4357 |
| DOI: |
10.3847/1538-4357/acb4ed |
| Access URL: |
https://doaj.org/article/9083d250d54b41d2b45da3300a5342d4 |
| Accession Number: |
edsdoj.9083d250d54b41d2b45da3300a5342d4 |
| Database: |
Directory of Open Access Journals |
