التفاصيل البيبلوغرافية
| العنوان: |
Third Epoch HST Imaging of a Nonradiative Shock in the Cygnus Loop Supernova Remnant. |
| المؤلفون: |
Sankrit, Ravi, Blair, William P., Raymond, John C. |
| المصدر: |
Astrophysical Journal; 5/10/2023, Vol. 948 Issue 2, p1-9, 9p |
| مصطلحات موضوعية: |
SUPERNOVA remnants, THERMAL instability, SHOCK waves, OPTICAL images, RANGE of motion of joints, MEDIAN (Mathematics), PARTICLE acceleration |
| مستخلص: |
We present new HST/WFC3 optical images of a region in the northeastern part of the Cygnus Loop supernova remnant, which includes a well-studied Balmer-line filament. These data represent the third epoch of HST H α imaging and a second epoch of [O iii ] λ 5007 imaging of that particular filament. The H α images were used to measure the proper motions at various locations along the shock front, and the values ranged from 55 to 85 mas yr−1 with a median value of 70 mas yr−1, which corresponds to a shock velocity of 240 km s−1. The proper motions between epochs 1 and 2 were the same as between epochs 2 and 3, implying that there has been no measurable deceleration of the shock in the 22 yr period between the first and third epochs. The range of proper motions (and therefore shock velocities) along the filament indicate variations of over a factor of two in the preshock density. The [O iii ] emission is prominent toward one end of the filament where the shock has transitioned from nonradiative to radiative. The proper motion is smaller than for the H α filaments, and it corresponds to a shock velocity of about 155 km s−1. The images obtained about 18 yr apart show that the [O iii ] morphology has not changed, which places limits on any short-timescale variations due to catastrophic cooling or thermal instabilities. We find that the effective shock age is less than the eddy turnover timescale, which implies that turbulence has not yet influenced the dynamics of the shock. [ABSTRACT FROM AUTHOR] |
|
Copyright of Astrophysical Journal is the property of IOP Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) |
| قاعدة البيانات: |
Complementary Index |
Full Text Finder