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The warp in Milky Way seen through the young stellar disk shows the complex structures. Its spatial distribution reveals the asymmetry in the vertical distance to the galactic midplane, whereas the kinematics shows the os- cillating motion. We analyze the warp using about 25,000 OB stars from Gaia Data Release 2, with Galactocentric azimuth (φ) range from 135◦ to 225◦. We detect the warp from two distinctive regions. First region (warp down) lies on 100◦ < l < 150◦ and second regions (warp up) lies on 150◦ < l < 220◦. The vertical position towards the Galactic midplane (Z) from all samples shows the line-of-nodes of the warp is on φ = 174◦ ± 2◦. The maximum deviation in warp down region reachs 0.1 kpc and 0.2 kpc in warp up region. The vertical velocity (VZ) from both regions are dominated by negative VZ. From the kinematics dis- tribution, it can be concluded that there is an oscillati1ng motion. Considering with the previous study, the oscillating motion was caused by the gravitational interaction with the Galaxy satellites. From this, we can constrain the origin of the warp is developing from the tidal interaction between Milky Way and its satellites. [ABSTRACT FROM AUTHOR]

Accurate and detailed three-dimensional (3D) maps of Galactic interstellar medium (ISM) are still lacking. One way to obtain such 3D descriptions is to record a large set of individual absorption or reddening measurements toward target stars located at various known distances and directions. The inversion of these measurements using a tomographic method can produce spatial distribution of the ISM. Until recently absorption data were very limited and distances to the target stars are still uncertain, but the situation will greatly improve thanks to current and future massive stellar surveys from ground, and to Gaia mission. To prepare absorption data for inversion from a huge number of stellar spectra, automated tools are needed. We have developed various spectral analysis tools adapted to different type of spectra, early- or late- type star. We also have used diffuse interstellar bands (DIBs) to trace IS structures and kinematics. Although we do not know yet their carriers, they can be a promising tool to trace distant interstellar clouds or Galactic arms. We present some examples of the interstellar fitting and show the potentiality of DIBs in tracing the ISM. We will also briefly show and comment the latest 3D map of the local ISM which reveal nearby cloud complexes and cavities. [ABSTRACT FROM AUTHOR]