We present new three-dimensional (3D) interstellar dust reddening maps of the Galactic plane in three colours, EpG´K S q, EpG BP´GRP q and EpH´K S q. The maps have a spatial angular resolution of 6 arcmin and covers over 7000 deg 2 of the Galactic plane for Galactic longitude 0˝ă l ă 360˝and latitude |b| ă 10˝. The maps are constructed from robust parallax estimates from the Gaia Data Release 2 (Gaia DR2) combined with the high-quality optical photometry from the Gaia DR2 and the infrared photometry from the 2MASS and WISE surveys. We estimate the colour excesses, EpG´K S q, EpG BP´GRP q and EpH´K S q, of over 56 million stars with the machine learning algorithm Random Forest regression, using a training data set constructed from the large-scale spectroscopic surveys LAMOST, SEGUE and APOGEE. The results reveal the large-scale dust distribution in the Galactic disk, showing a number of features consistent with the earlier studies. The Galactic dust disk is clearly warped and show complex structures possibly spatially associated with the Sagittarius, Local and Perseus arms. We also provide the empirical extinction coefficients for the Gaia photometry that can be used to convert the colour excesses presented here to the line-of-sight extinction values in the Gaia photometric bands.

We present a three dimensional extinction map in r band. The map has a spatial angular resolution, depending on latitude, between 3 -9 arcmin and covers the entire XSTPS-GAC survey area of over 6,000 deg 2 for Galactic longitude 140 ď l ď 220 deg and latitude´40 ď b ď 40 deg. By cross-matching the photometric catalog of the Xuyi Schmidt Telescope Photometric Survey of the Galactic Anticentre (XSTPS-GAC) with those of 2MASS and WISE, we have built a multi-band photometric stellar sample of about 30 million stars and applied spectral energy distribution (SED) fitting to the sample. By combining photometric data from the optical to the near-infrared, we are able to break the degeneracy between the intrinsic stellar colours and the amounts of extinction by dust grains for stars with high photometric accuracy, and trace the extinction as a function of distance for low Galactic latitude and thus highly extincted regions. This has allowed us to derive the best-fit extinction and distance information of more than 13 million stars, which are used to construct the three dimensional extinction map. We have also applied a Rayleigh-Jeans colour excess (RJCE) method to the data using the 2MASS and WISE colour pH´W2q. The resulting RJCE extinction map is consistent with the integrated two dimensional map deduced using the best-fit SED algorithm. However for individual stars, the amounts of extinction yielded by the RJCE method suffer from larger errors than those given by the best-fit SED algorithm.

We introduce the LAMOST Stellar Parameter Pipeline at Peking University -LSP3, developed and implemented for the determinations of radial velocity V r and stellar atmospheric parameters (effective temperature T eff , surface gravity log g, metallicity [Fe/H]) for the LAM-OST Spectroscopic Survey of the Galactic Anti-center (LSS-GAC). We describe the algorithms of LSP3 and examine the accuracy of parameters yielded by it. The precision and accuracy of parameters yielded are investigated by comparing results of multi-epoch observations and of candidate members of open and globular clusters, with photometric calibration, as well as with independent determinations available from a number of external databases, including the PASTEL archive, the APOGEE, SDSS and RAVE surveys, as well as those released in the LAMOST DR1. The uncertainties of LSP3 parameters are characterized and quantified as a function of the spectral signal-to-noise ratio (SNR) and stellar atmospheric parameters. We conclude that the current implementation of LSP3 has achieved an accuracy of 5.0 km s −1 , 150 K, 0.25 dex, 0.15 dex for the radial velocity, effective temperature, surface gravity and metallicity, respectively, for LSS-GAC spectra of FGK stars of SNRs per pixel higher than 10. The LSP3 has been applied to over a million LSS-GAC spectra collected hitherto. Stellar parameters yielded by the LSP3 will be released to the general public following the data policy of LAMOST, together with estimates of the interstellar extinction E(B − V ) and stellar distances, deduced by combining spectroscopic and multi-band photometric measurements using a variety of techniques.

Magnetars may have strong surface dipole field. Observationally, two magnetars may have passive fallback disks. In the presence of a fallback disk, the rotational evolution of magnetars may be changed. In the self-similar fallback disk model, it is found that: (1) When the disk mass is significantly smaller than 10 −6 M ⊙ , the magnetar is unaffected by the fallback disk and it will be a normal magnetar. (2) When the disk mass is large, but the magnetar's surface dipole field is about or below 10 14 G, the magnetar will also be a normal magnetar. A magnetar plus a passive fallback disk system is expected. This may correspond to the observations of magnetars 4U 0142+61, and 1E 2259+586. (3) When the disk mass is large, and the magnetar's surface dipole field is as high as 4 × 10 15 G, the magnetar will evolve from the ejector phase to the propeller phase, and then enter rotational equilibrium. The magnetar will be slowed down quickly in the propeller phase. The final rotational period can be as high 2 × 10 4 s. This may correspond to the super-slow magnetar in the supernova remnant RCW 103. Therefore, the three kinds of magnetars can be understood in a unified way.