Cassiopeia A(Cas A) is a well-known candidate for studying cosmic-ray acceleration, in which compact features of various scales have attracted much attention. Based on observations by the Very Large Array of Cas A at ...Cassiopeia A(Cas A) is a well-known candidate for studying cosmic-ray acceleration, in which compact features of various scales have attracted much attention. Based on observations by the Very Large Array of Cas A at 6 cm and 21 cm, we measure the spectral index distribution of various scale components using the observation of the 1998 epoch. We decompose its total density image into nine scale components, and map the temperature spectral index distribution of each component, which ranges from-2.48 ± 0.01 to-2.91 ± 0.05. We find that the spectral indices increase from the small scale to large scale components. A damped post-shock magnetic field model with a strength larger than ~200 μG and a damping length scale less than ~10% of the remnant radius can account for the spectral index variation naturally.展开更多
We take advantage of red clump stars to build the relation of the optical extinction(AV) and distance in each direction of supernova remnants(SNRs) with known extinction in the fourth Galactic quadrant.The distances o...We take advantage of red clump stars to build the relation of the optical extinction(AV) and distance in each direction of supernova remnants(SNRs) with known extinction in the fourth Galactic quadrant.The distances of nine SNRs are determined well by this method.Their uncertainties range from 10% to30%,which are significantly improved for eight SNRs,G279.0+1.1,G284.3–1.8,G296.1–0.5,G299.2–2.9,G308.4–1.4,G309.2–0.6,G309.8–2.6 and G332.4–0.4.In addition,SNR G284.3–1.8 with the new distance of 5.5 kpc is not likely associated with the PSR J1016–5857 at 3 kpc.展开更多
基金support from the National Natural Science Foundation of China(NSFC,Grant Nos.12041301 and 12073039)the China Manned Space Project(CMS-CSST2021-A09)the Youth Innovation Promotion Association of CAS(2023000015)。
文摘Cassiopeia A(Cas A) is a well-known candidate for studying cosmic-ray acceleration, in which compact features of various scales have attracted much attention. Based on observations by the Very Large Array of Cas A at 6 cm and 21 cm, we measure the spectral index distribution of various scale components using the observation of the 1998 epoch. We decompose its total density image into nine scale components, and map the temperature spectral index distribution of each component, which ranges from-2.48 ± 0.01 to-2.91 ± 0.05. We find that the spectral indices increase from the small scale to large scale components. A damped post-shock magnetic field model with a strength larger than ~200 μG and a damping length scale less than ~10% of the remnant radius can account for the spectral index variation naturally.
基金supports from the National Key R&D Programs of China (2018YFA0404203)the National Natural Science Foundation of China (Grant Nos. 11603039 and U1831128)
文摘We take advantage of red clump stars to build the relation of the optical extinction(AV) and distance in each direction of supernova remnants(SNRs) with known extinction in the fourth Galactic quadrant.The distances of nine SNRs are determined well by this method.Their uncertainties range from 10% to30%,which are significantly improved for eight SNRs,G279.0+1.1,G284.3–1.8,G296.1–0.5,G299.2–2.9,G308.4–1.4,G309.2–0.6,G309.8–2.6 and G332.4–0.4.In addition,SNR G284.3–1.8 with the new distance of 5.5 kpc is not likely associated with the PSR J1016–5857 at 3 kpc.
