Spiral galaxy ESO 137-001 imaged by Hubble with Wide Field Camera 3

Credit: ESA, NASA

This new Hubble image shows spiral galaxy ESO 137-001, framed against a bright background as it moves through the heart of galaxy cluster Abell 3627. This image not only captures the galaxy and its backdrop in stunning detail, but also something more dramatic — intense blue streaks streaming outwards from the galaxy, seen shining brightly in ultraviolet light. These streaks are in fact hot, wispy streams of gas that are being torn away from the galaxy by its surroundings as it moves through space. This violent galactic disrobing is due to a process known as ram pressure stripping — a drag force felt by an object moving through a fluid.

Update: Parallaxes have been found for and an astrometric search for planets performed around 20 southern ultracool dwarfs, and further study has been carried out on the possible disintegrating sub-Mercury sized exoplanet KIC 12557548b. Finally, the importance of binarity and higher stellar multiplicity has long been known, and a new review has investigated the phenomenon as it manifests at the earliest stages of stellar evolution. The review investigates the possible loss of companions through dynamical effects as newly formed stellar groupings evolve:

Surveys of Class 0 protostars with mm interferometers have revealed a very high multiplicity frequency of about 2/3, even though there are observational difficulties in resolving close protobinaries, thus supporting the possibility that all stars could be born in multiple systems. Near-infrared adaptive optics observations of Class I protostars show a lower binary frequency relative to the Class 0 phase, a declining trend that continues through the Class II/III stages to the field population. This loss of companions is a natural consequence of dynamical interplay in small multiple systems, leading to ejection of members. […] Many stars are born in clusters and small groups, and we discuss how interactions in dense stellar environments can significantly alter the distribution of binary separations through dissolution of wider binaries.

Update: the coolest isolated brown dwarf in the TW Hydrae association. The object has spectral type L1, exhibits signs of low surface gravity and thus youth, and has probably 11 – 15 Jupiter masses.


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