X-ray Behaviors Of Multi-scale Star Activities

The appearance of X-ray emission represents the existence of violent processes. On one hand, X-rays are emitted from stars via different magnetic and/or shock activities, on the other hand, the kinetic energy emanated from O-type stars via line-driven stellar wind or from massive stars via core-collapse supernova explosion heats the ambient medium as well as the mass they sent out to millions degree, which emits X-ray photons. Therefore, the investigation of X-ray perspective of stars in the different scales of assembly and environments will help us to understand the stellar physics as well as the feedback mechanism of young stars.We performed analyses of the X-ray observations of stars of three different assemblies:a supernova remnant (SNR) N11L in the Large Magellanic Cloud (LMC), a massive star-forming region (MSFR) NGC602in the Small Magellanic Cloud (SMC), and three giant Ha regions (GHRs):NGC5461, NGC5462, and NGC5471, in the spiral galaxy M101. They are located in different environments.Firstly, we performed a Chandra X-ray study of the SNR N11L in the LMC. The X-ray emission is predominantly distributed within the main shell and the northern loop-like filaments traced by the optical narrow band images, with an indistinct extension along the north area. The brightest emission comes from a northeast-south--west ridge, and peaks at two patches at center and southwest. Spectral analysis indicates that the blast wave is propagating in an inhomogenous environment, and the X-ray emission overall is dominated by thermal gas whose composition is consistent with swept-up ambient meterial. The ionization time of the hot plasma implied by the X-ray spectral analysis is consistent with the Sedov age of the SNR derived from the best-fit parameters and the apparent radius of the SNR based on the optical images, however, the consequent explosion energy is not only at least one order of magnitude less than the canonical value of1051ergs, but also accounts for a small portion of the thermal energy of the hot gas. That discrepancy supports the blown-out scenario. Secondly, we report the discovery of extended X-ray emission within the young star cluster NGC602a in the Wing of the SMC based on observations obtained with the Chandra X-Ray Observatory. X-ray emission is detected from the cluster core area with the highest stellar density and from a dusty ridge surrounding the\hii～region. We use a census of massive stars in the cluster to demonstrate that a cluster wind or wind-blown bubble is unlikely to provide a significant contribution to the X-ray emission detected from the central area of the cluster. We therefore suggest that X-ray emission at the cluster core originates from an ensemble of low-and solar-mass pre-main-sequence (PMS) stars, which would be too weak in X-rays to be detected individually. We attribute the X-ray emission from the dusty ridge to the embedded tight cluster of the newborn stars known in this area from infrared studies. Assuming that the levels of X-ray activity in young stars in the low-metallicity environment of NGC602a are comparable to their Galactic counterparts, then the detected spatial distribution, spectral properties, and level of X-ray emission are largely consistent with those expected from low-and solar-mass PMS stars and young stellar objects (YSOs). This is the first discovery of X-ray emission attributable to PMS stars and YSOs in the SMC, which suggests that the accretion and dynamo processes in young, low-mass objects in the SMC resemble those in the Galaxy.Thirdly, we performed Chandra X-ray study of three GHRs in the spiral galaxy M101, NGC5461, NGC5462, and NGC5471.The X-ray spectra of the three GHRs all contain a prominent thermal component with a temperature of-0.2keV. In NGC5461, the spatial distribution of the soft (<1.5keV) X-ray emission is generally in agreement with the extent of H1105, the most luminous H～Ⅱ region therein, but extends beyond its southern boundary, which could be attributed to outflows from the star cloud between H1105and H1098. In NGC5462, the X-ray emission is displaced from the H Ⅱ regions and a ridge of blue stars; the H$\alpha$filaments extending from the ridge of star cloud to the diffuse X-rays suggest that hot gas outflows have occurred. The X-rays from NGC5471are concentrated at the B-knot, a "hypernova remnant" candidate. Assuming a Sedov-Taylor evolution, the derived explosion energy, on the order of105ergs, is consistent with a hypernova origin. In addition, a bright source in the field of NGC5462has been identified as a background AGN, instead of a black hole X-ray binary in M101.Finally, we summarized the X-ray properties of the three different contents, and compared their X-ray luminosities with those of the other well-known massive star-forming regions. We present a positive correlation between the H luminosity and the X-ray luminosity of the MSFRs. However, this correlation is a crude estimation, and further detailed investigation is needed. On the other hand, more objects and more pieces of information are needed to achieve a better understanding of the feedback process in the single stellar nebula (stellar wind bubble and supernova remnant), massive star-forming region, and star-forming complex, and the link between them. An arrangement for future work is planned based on those deficits.