t We present high spatial resolution X-ray spectroscopy of Tycho＇s supernova remnant （SNR） using observational data from Chandra. The whole remnant was divided into 26 × 27 regions, with each of them covering...t We present high spatial resolution X-ray spectroscopy of Tycho＇s supernova remnant （SNR） using observational data from Chandra. The whole remnant was divided into 26 × 27 regions, with each of them covering 20＂× 20＂. We selected 536 pixels with enough events to generate spectra and fit them with an absorbed two component non-equilibrium ionization model. We obtained maps of absorbing column density, weight-averaged temperature, ionization age and abundances for O, Ne, Mg, Si, S and Fe, with emission used to determine the weight. The abundance maps and the finding that Fe abundance is not correlated with any other element suggest that Fe is located at a smaller radius than other elements, supporting the onion shell model with emission from more massive elements peaking more toward the center. A tight correlation between Si and S abundances support both Si and S coming from explosive O-burning and/or incomplete Si-burning. O and Ne abundances show no correlation with any other element. Considering that O, Ne and Mg are all synthesized in the same process （C/Ne-burning）, we suggest that O/Ne/Mg might mix well with other elements during the explosion of the supernova and the expansion of the SNR.展开更多
We have carried out CO J=2 - 1 and CO J = 3 - 2 observations toward Tycho＇s supernova remnant （SNR） using the KOSMA 3m-telescope. From these observations, we identified three molecular clouds （MCs） around the SNR...We have carried out CO J=2 - 1 and CO J = 3 - 2 observations toward Tycho＇s supernova remnant （SNR） using the KOSMA 3m-telescope. From these observations, we identified three molecular clouds （MCs） around the SNR. The small cloud in the southwest was discovered for the first time. In the north and east, two MCs （Cloud A and Cloud B） adjacent in space display a bow-shaped morphology, and have broad emission lines, which provide some direct evidences of the SNR-MCs interaction. The MCs are revealed at-69∽-59 km s-1, coincident with Tycho＇s SNR. The MCs associated with Tycho＇s SNR have a mass of-2.13 x 10^3 Mo. Position- velocity diagrams show the two clouds to be adjacent in velocity, which means cloud- cloud collision could occur in this region. The maximum value （0.66±0.10） of the integrated CO line intensity ratio （IcoJ=3-2/Icoj=2-1） for the three MCs agrees well with the previous measurement of individual Galactic MCs, implying that the SNR shock drove into the MCs. The two MCs have a line intensity ratio gradient. The distribution of the ratio appears to indicate that the shock propagates from the southwest to the northeast.展开更多
The thin layer approximation applied to the expansion of a supernova remnant assumes that all the swept mass resides in a thin shell. The law of motion in the thin layer approximation is therefore found using the cons...The thin layer approximation applied to the expansion of a supernova remnant assumes that all the swept mass resides in a thin shell. The law of motion in the thin layer approximation is therefore found using the conservation of momentum. Here we instead introduce the conservation of energy in the framework of the thin layer approximation. The first case to be analysed is that of an interstellar medium with constant density and the second case is that of 7 profiles of decreasing density with respect to the centre of the explosion. The analytical and numerical results are applied to 4 supernova remnants: Tycho, Cas A, Cygnus loop, and SN 1006. The back reaction due to the radiative losses for the law of motion is evaluated in the case of constant density of the interstellar medium.展开更多
In this paper we derive three equations of motion for a supernova remnant (SNR) in the framework of the thin layer approximation using the Padé approximant. The circumstellar medium is assumed to follow a density...In this paper we derive three equations of motion for a supernova remnant (SNR) in the framework of the thin layer approximation using the Padé approximant. The circumstellar medium is assumed to follow a density profile of either an exponential type, a Gaussian type, or a Lane-Emden (n = 5) type. The three equations of motion are applied to four SNRs: Tycho, Cas A, Cygnus loop, and SN 1006. The percentage error of the Padé approximated solution is always less than 10%. The theoretical decrease of the velocity over ten years for SNRs is evaluated.展开更多
基金supported by the National Natural Science Foundation of China(NSFC,Grant No.11473023)Hunan Provincial Natural Science Foundation(2015JJ3124)
文摘t We present high spatial resolution X-ray spectroscopy of Tycho＇s supernova remnant （SNR） using observational data from Chandra. The whole remnant was divided into 26 × 27 regions, with each of them covering 20＂× 20＂. We selected 536 pixels with enough events to generate spectra and fit them with an absorbed two component non-equilibrium ionization model. We obtained maps of absorbing column density, weight-averaged temperature, ionization age and abundances for O, Ne, Mg, Si, S and Fe, with emission used to determine the weight. The abundance maps and the finding that Fe abundance is not correlated with any other element suggest that Fe is located at a smaller radius than other elements, supporting the onion shell model with emission from more massive elements peaking more toward the center. A tight correlation between Si and S abundances support both Si and S coming from explosive O-burning and/or incomplete Si-burning. O and Ne abundances show no correlation with any other element. Considering that O, Ne and Mg are all synthesized in the same process （C/Ne-burning）, we suggest that O/Ne/Mg might mix well with other elements during the explosion of the supernova and the expansion of the SNR.
基金supported by the National Natural Science Foundation of China(Grant No. 10473014)
文摘We have carried out CO J=2 - 1 and CO J = 3 - 2 observations toward Tycho＇s supernova remnant （SNR） using the KOSMA 3m-telescope. From these observations, we identified three molecular clouds （MCs） around the SNR. The small cloud in the southwest was discovered for the first time. In the north and east, two MCs （Cloud A and Cloud B） adjacent in space display a bow-shaped morphology, and have broad emission lines, which provide some direct evidences of the SNR-MCs interaction. The MCs are revealed at-69∽-59 km s-1, coincident with Tycho＇s SNR. The MCs associated with Tycho＇s SNR have a mass of-2.13 x 10^3 Mo. Position- velocity diagrams show the two clouds to be adjacent in velocity, which means cloud- cloud collision could occur in this region. The maximum value （0.66±0.10） of the integrated CO line intensity ratio （IcoJ=3-2/Icoj=2-1） for the three MCs agrees well with the previous measurement of individual Galactic MCs, implying that the SNR shock drove into the MCs. The two MCs have a line intensity ratio gradient. The distribution of the ratio appears to indicate that the shock propagates from the southwest to the northeast.
文摘The thin layer approximation applied to the expansion of a supernova remnant assumes that all the swept mass resides in a thin shell. The law of motion in the thin layer approximation is therefore found using the conservation of momentum. Here we instead introduce the conservation of energy in the framework of the thin layer approximation. The first case to be analysed is that of an interstellar medium with constant density and the second case is that of 7 profiles of decreasing density with respect to the centre of the explosion. The analytical and numerical results are applied to 4 supernova remnants: Tycho, Cas A, Cygnus loop, and SN 1006. The back reaction due to the radiative losses for the law of motion is evaluated in the case of constant density of the interstellar medium.
文摘In this paper we derive three equations of motion for a supernova remnant (SNR) in the framework of the thin layer approximation using the Padé approximant. The circumstellar medium is assumed to follow a density profile of either an exponential type, a Gaussian type, or a Lane-Emden (n = 5) type. The three equations of motion are applied to four SNRs: Tycho, Cas A, Cygnus loop, and SN 1006. The percentage error of the Padé approximated solution is always less than 10%. The theoretical decrease of the velocity over ten years for SNRs is evaluated.
