The Lyman-alpha Solar Telescope(LST) for the ASO-S mission——Ⅱ. design of LST

As one of the three payloads for the Advanced Space-based Solar Observatory(ASO-S)mission,the Lyman-alpha(Lyα)Solar Telescope(LST)is composed of three instruments:a Solar Corona Imager(SCI),a LyαSolar Disk Imager(SDI)and a full-disk White-light Solar Telescope(WST).When working in-orbit,LST will simultaneously perform high-resolution imaging observations of all regions from the solar disk to the inner corona up to 2.5 R⊙(R⊙stands for the mean solar radius)with a spatial resolution of 4.8′′and 1.2′′for coronal and disk observations,respectively,and a temporal resolution of 30–120 s and 1–120 s for coronal and disk observations,respectively.The maximum exposure time can be up to20 s due to precise pointing and image stabilization function.Among the three telescopes of LST,SCI is a dual-waveband coronagraph simultaneously and independently observing the inner corona in the HI Lyα(121.6±10 nm)line and white light(WL)(700±40 nm)wavebands by using a narrowband Lyαbeam splitter and has a field of view(FOV)from 1.1 to 2.5 R⊙.The stray-light suppression level can attain<10^-6 B⊙(B⊙is the mean brightness of the solar disk)at 1.1 R⊙and≤5×10^-8 B⊙at 2.5 R⊙.SDI and WST are solar disk imagers working in the Lyαline and 360.0 nm wavebands,respectively,which adopt an off-axis two-mirror reflective structure with an FOV up to 1.2 R⊙,covering the inner coronal edge area and relating to coronal imaging.We present the up-to-date design for the LST payload.

The dying accretion and jet in a powerful radio galaxy of Hercules A

Hercules A(Her A)is one of a rare class of dying and transition-type objects,which has a pair of giant,powerful radio lobes and a weak radio core.We reduce and analyze the radio data of Her A that were observed by the Expanded Very Large Array(EVLA)during 2010-2011 at C band.The intensity distribution is very smooth along the edge of the lobe front and the intensity also sharply decreases at the edge,which supports that magnetic fields may play an important role in radio lobes.The spectrum of the weak core is very steep and the core flux becomes weaker by about ten percent when compared to what was observed twenty years ago,which suggest that the central engine is still dying quickly.Her A deviates a lot from the relation between[O III]luminosity and low-frequency 178 MHz luminosity(LO III-L178 MHz)as defined by other FR I/II sources.However,when only radio core emission is considered,it roughly follows an LO III-L178 MHzcorrelation.This result supports that the black-hole accretion and large-scale jet in Her A did not evolve simultaneously,and indicates that although the large-scale jet is still powerful,the accretion and inner jet have changed into an inactive state.Based on the estimated Bondi accretion rate,we model the spectrum of Her A with a radiatively inefficient accretion flow and jet model.

Development and calibration of the Moon-based EUV camera for Chang'e-3

The process of development and calibration for the first Moon-based ex- treme ultraviolet （EUV） camera to observe Earth＇s plasmasphere is introduced and the design, test and calibration results are presented. The EUV camera is composed of a multilayer film mirror, a thin film filter, a photon-counting imaging detector, a mech- anism that can adjust the direction in two dimensions, a protective cover, an electronic unit and a thermal control unit. The center wavelength of the EUV camera is 30.2 nm with a bandwidth of 4.6nm. The field of view is 14.7° with an angular resolution of 0.08°, and the sensitivity of the camera is 0.11 count s-1 Rayleigh-1. The geomet- ric calibration, the absolute photometric calibration and the relative photometric cal- ibration are carried out under different temperatures before launch to obtain a matrix that can correct geometric distortion and a matrix for relative photometric correction, which are used for in-orbit correction of the images to ensure their accuracy.

Extending the correlation of L_R-L_X to gamma-ray bursts

The well-known correlation between radio luminosity （LR） and X-ray luminosity （Lx）, LR/LX 10^-5, holds for a variety of objects, such as active galactic nuclei, Galactic black holes, solar flares and cool stars. Here we extend the relation to gamma-ray bursts （GRBs） and find that the GRBs also obey a similar LR - LX relation, with a slightly different slope of LR ∝ LX^1.1. This relation implies that the explosions that occur on different scales may have a common underlying origin.

X-ray spectral evolution in an X-ray changing-look AGN NGC 1365 with variable column density

X-ray changing-look active galactic nuclei(CL AGNs) are a subpopulation of AGNs,whose lineof-sight column densities increase/decrease within several years.The physical mechanism for the variation of column density is unclear.We reduce the X-ray data from XMM-Newton and Nu STAR observations for a CL AGN NGC 1365 with strong variation of column densities.The X-ray spectrum quickly softens as the X-ray luminosity increases and optical-to-X-ray spectral index also increases as increasing of optical luminosity.These results support that NGC 1365 also undergoes strong spectral evolution as that recently suggested for the optically selected CL AGNs with reappearance/disappearance of broad emission lines.Therefore,the variation of column density may be driven by the variable disk winds during the strong evolution of disk/corona.

Constraining evolution of magnetic field strength in the dissipation region of two BL Lac objects

With the assumption that the optical variability timescale is dominated by the cooling time of the synchrotron process for BL Lac objects,we estimate time dependent magnetic field strength of the emission region for two BL Lac objects.The average magnetic field strengths are consistent with those estimated from core shift measurement and spectral energy distribution modelling.Variation of magnetic field strength in the dissipation region is discovered.Variability of flux and magnetic field strength shows no clear correlation,which indicates the variation of magnetic field is not the dominant reason of the variability origin.The evolution of magnetic field strength can provide another approach to constrain the energy dissipation mechanism in jets.