This is a pannable and zoomable face-on map of the Milky Way galaxy within about 650 pc (2100 ly) of the Sun. It is derived from density isosurfaces of subsets of the 1069480 stars that had relatively low error measurements (error/parallax < 0.2) in the Tycho-Gaia Astrometric Solution (TGAS) star parallax catalog released as part of Gaia DR1.
As Tycho-2 is very uncomplete beyond relative magnitude 11, I have restricted the star selection to only stars with relative magnitude < 11. I used a subset of these stars that should be visible throughout the 650 parsec radius (ignoring dust). This implies an absolute magnitude of approximately 1.5, so I have restricted the stars used for mapping to those with an absolute magnitude of 1.5 or brighter.
The green "bright" star density isosurfaces are computed using about 140 thousand stars and a gaussian normal with a sigma of 8 parsecs. The blue "hot" star density isosurfaces are computed using the 3368 star subset of the bright stars with colour index <= -0.02 and a gaussian normal with a sigma of 8 parsecs.
The more dense bright star cloud displayed on the map is the 70% density isosurface. The less dense cloud is defined as the regions of the 55% isosurface that contain 70% density clouds. The more dense hot star cloud is the 30% isosurface and the less dense hot star cloud is the 20% isosurface.
The stars actually displayed on the map are not the complete set used for mapping, but are the stars found within the 15% density hot star isosurface or the 45% density bright star isosurface. In effect, the map shows the denser concentrations of stars in the solar neigbourhood and the brightest stars within those denser concentrations.
Check the Galaxymap blog for more details on how these isosurfaces were constructed.
The dust surfaces were kindly provided by Lucky Puspitarini and are from research published in Lallement, R., Vergely, J. L., Valette, B., Puspitarini, L., Eyer, L., & Casagrande, L. (2014). 3D maps of the local ISM from inversion of individual color excess measurements. Astronomy & Astrophysics, 561, A91.
The direction of the centre of the galaxy is towards the top of the map.
You can use the controls at the upper right to select the isosurfaces to display, turn the dust view off or on and select general map and/or more detailed isosurface labels. Beneath the search box are two options:
At the upper left are controls to zoom in and out and return to the home view.
You can also move left, right, up and down by dragging your mouse, using the arrow keys, or using the WASD keys. You can zoom in and out using the + and - keys or your mouse wheel.
Clicking or tapping will zoom into the current position. Double clicking/tapping will move the map to the current location of the tap or mouse pointer.
Individual star data is activated at the highest zoom level. Hovering over a star will give its name and distance above and below the galactic plane. Clicking on a star will bring up a box that describes the star in more detail, including links to the Tycho star map, SIMBAD, and various Vizier star catalogs.
The galactic longitude and distance from the Sun along the galactic plane of the current mouse pointer location appear at the lower left.
The isosurface labels list the identifier, a name, the distance of the centre of the isosurface in parsecs from the galactic plane, and the number of bright stars / hot stars located within the isosurface.
The names given to the isosurfaces and other map regions are purely my own invention but are derviced where ever possible from the names of star clusters or the brightest star found within the region.
Kevin Jardine
Galaxy Map