麻豆淫院

This new NASA/ESA/CSA James Webb Space Telescope Picture of the Month presents HH 30 in unprecedented detail. This target is an edge-on protoplanetary disk that is surrounded by jets and a disk wind, and is located in the dark cloud LDN 1551 in the Taurus Molecular Cloud.

Herbig-Haro objects, like HH 30, are luminous regions surrounding newborn stars (known as protostars). They form when stellar winds or jets of gas spewing from these newborn stars form shockwaves as they collide with nearby gas and dust at high speeds.

HH 30 is of particular interest to astronomers. In fact, the HH 30 disk is considered the prototype of an edge-on disk, thanks to its early discovery with the NASA/ESA Hubble Space Telescope. Disks seen from this view are a unique laboratory to study how dust grains drift and settle.

An international team of astronomers have used Webb to investigate the target in great detail. By combining Webb's observations with those from the Hubble Space Telescope and the Atacama Large Millimeter/submillimeter Array (ALMA), the team was able to study the multiwavelength disk appearance of the system.

The long-wavelength data from ALMA trace the location of millimeter-sized dust grains, which are found in a narrow region in the central plane of the disk. The shorter-wavelength infrared data from Webb reveal the distribution of smaller dust grains. These grains are only one millionth of a meter across鈥攁bout the size of a single bacterium. While the large dust grains are concentrated in the center of the disk, the small grains are much more widespread.

These Webb observations were taken as part of the Webb GO program #2562 (PI F. Me虂nard, K. Stapelfeldt), which aims to understand how dust evolves in edge-on disks like HH 30. Combined with the keen radio-wavelength eyes of ALMA, these observations show that large dust grains must migrate within the disk and settle in a thin layer. The creation of a narrow, dense layer of dust is an important stage in the process of planet formation. In this dense region, dust grains clump together to form pebbles and eventually planets themselves.

In addition to the behavior of dust grains, the Webb, Hubble, and ALMA images reveal several distinct structures that are nested within one another. A high-velocity jet of gas emerges at a 90-degree angle from the narrow central disk. The narrow jet is surrounded by a wider, cone-shaped outflow. Enclosing the conical outflow is a wide nebula that reflects the light from the young star that is embedded within the disk. Together, these data reveal HH 30 to be a dynamic place, where tiny dust grains and massive jets alike play a role in the formation of new planets.