Thanks to the Hα narrowband filter, VPHAS+ will reveal emission line objects of the following types:
- Wolf-Rayet and other massive evolved emission line stars
- Compact planetary nebulae and rapidly evolving post-AGB stars
- Be stars of all types - including young Herbig stars
- Clustered and field T Tau stars
- A range of interacting binary stars: symbiotics, 'supersoft'
compact binaries, WD/NS/BH accreting binaries
The inclusion of the u band filter enables selection of the following:
- white dwarfs and hot subdwarfs, horizontal branch stars
- reddened OB stars (at visual extinction of up to 10 magnitudes)
- interacting binaries dominated by a hot companion
- planetary nebula central stars
Different filter combinations also support effective selection of:
- large numbers of reddened A-type stars via strong Hα
absorption
- post common-envelope binaries
- red giants and dwarfs, located within distinct colour-colour tracks
The Hα narrowband images reveal diffuse ionised nebulae
of all types: HII regions, supernova remnants, spatially-resolved
planetary nebulae. The sensitivity of the r-Hα colour to
intrinsic stellar colour can also be exploited along with
the broadband data to trace line-of-sight extinction, at high
angular resolution.