{"id":12882,"date":"2016-07-13T13:00:04","date_gmt":"2016-07-13T17:00:04","guid":{"rendered":"http:\/\/hobbyspace.com\/Blog\/?p=12882"},"modified":"2016-07-13T01:23:18","modified_gmt":"2016-07-13T05:23:18","slug":"eso-young-stars-outburst-pushes-protoplanetary-disc-snow-line-outward","status":"publish","type":"post","link":"https:\/\/hobbyspace.com\/Blog\/?p=12882","title":{"rendered":"ESO: Young star’s outburst pushes protoplanetary disc snow line outward"},"content":{"rendered":"

ESO<\/a>\u00a0(European Southern Observatory) releases another report this week:<\/p>\n

Stellar Outburst Brings Water Snow Line Into View<\/a>\u00a0<\/strong><\/p>\n

\"This<\/a>
This artist\u2019s impression of the water snowline around the young star V883 Orionis, as detected with ALMA.<\/em><\/figcaption><\/figure>\n

The Atacama Large Millimeter\/submillimeter Array (ALMA) has made the first ever resolved observation of a water snow line within a protoplanetary disc. This line marks where the temperature in the disc surrounding a young star drops sufficiently low for snow to form. A dramatic increase in the brightness of the young star V883 Orionis flash heated the inner portion of the disc, pushing the water snow line out to a far greater distance than is normal for a protostar, and making it possible to observe it for the first time. The results are published in the journal Nature on 14 July 2016.<\/p>\n

\"This<\/a>
This image of the planet-forming disc around the young star V883 Orionis was obtained by ALMA in long-baseline mode. This star is currently in outburst, which has pushed the water snow line further from the star and allowed it to be detected for the first time. The dark ring midway through the disc is the water snowline, the point from the star where the temperature and pressure dip low enough for water ice to form.<\/em><\/figcaption><\/figure>\n

\"eso1626e[1]\"<\/a>
Same image but with orbits of the planet Neptune and dwarf planet Pluto in our Solar System are shown for scale.<\/em><\/figcaption><\/figure>Young stars are often surrounded by dense, rotating discs of gas and dust, known as protoplanetary discs, from which planets are born. The heat from a typical young solar-type star means that the water within a protoplanetary disc is gaseous up to distances of around 3 au<\/a> from the star [1]<\/a> \u2014 less than 3 times the average distance between the Earth and the Sun \u2014 or around 450 million kilometres [2]<\/a>. Further out, due to the extremely low pressure, the water molecules transition directly from a gaseous state to form a patina of ice on dust grains and other particles. The region in the protoplanetary disc where water transitions between the gas and solid phases is known as the water snow line [3]<\/a>.<\/p>\n
\"This<\/a>
This illustration shows how the outburst of the young star V883 Orionis has displaced the water snowline much further out from the star, and rendered it detectable with ALMA.<\/em><\/figcaption><\/figure>\n

But the star V883 Orionis is unusual. A dramatic increase in its brightness has pushed the water snow line out to a distance of around 40 au (about 6 billion kilometres or roughly the size of the orbit of the dwarf planet Pluto <\/a>in our Solar System). This huge increase, combined with the resolution of ALMA at long baselines [4]<\/a>, has allowed a team led by Lucas Cieza (Millennium ALMA Disk Nucleus<\/a> and Universidad Diego Portales, Santiago, Chile) to make the first ever resolved observations of a water snow line in a protoplanetary disc.<\/p>\n