Their observations confirm that the salty regions trace the location of the
circumstellar disk.
The dark region at the centre of the image is due to a coronagraph, a mask which blocks the blinding light of the central star and allows astronomers to detect its much fainter disc (rotating
circumstellar disk of dense gas and dust surrounding a young newly formed star) and its planetary companion.
It must be terrestrial, it must have water, it must be in the
circumstellar habitable zone (where water can be liquid someplace), it must have a magnetosphere to protect from cosmic rays, and it must be in a planetary system within the galactic habitable zone --among other criteria.
It has since been identified as the prototypical cometary nebula, a class of fan-shaped reflection nebulae that are often associated with T Tauri stars (very young, variable, low-mass stars often in binary systems; some have
circumstellar disks and are likely progenitors of planetary systems).
(111) The composition, molecular abundances (112), and physical characteristics of the ISM such as temperature, density, and the intensity and type of electromagnetic and cosmic radiation of interstellar,
circumstellar, and protostellar clouds have provided additional insight into the constraints and possibilities for the creation or destruction of advanced organic chemistry.
Among specific topics are dynamics of wind and variations of
circumstellar extinction in the accreting T.
G., "Resolving the
Circumstellar Disk of HL Tauri at Millimeter Wavelengths", ApJ, 741, 1, id.
As with discussions of
circumstellar habitable zones, some simplifying assumptions are helpful.