Rewinding stellar evolution: The last 400,000 years of mass loss from a star
April 11th 2017
The study of K4-37, a planetary nebula never studied in detail before, allows us to trace back the mass loss history of its last stages as a star
The study makes use of data from Calar Alto and San Pedro Martir (Mexico) observatories
Planetary Nebulae (hereafter PNe) are the last evolutionary phase of stars with initial masses between 0.8 and 8 solar masses (Msun). They appear as a compact central star (the remains of the progenitor star) surrounded by a bright shell of expanding gas, produced during the previous red giant phase, when the star blew away its external layers. In a few tens of thousand years, PNe disperse in the interstellar medium. Although more than 3,500 PNe are known to date in the Milky Way, many of them lack appropriate observations to place them in the general context of PN evolution. The study of K4-37, one of these less observed PNe, gives new hints to this context.
SN2015bh: end of star or supernova “impostor”?
March 14th 2017
Astronomers spot an intense explosion of a massive star, which, according to records, experienced frequent eruptions for at least 20 years
The analysis of the outburst does not allow to discern between a real supernova - an explosive event marks the end of a star - or a giant eruption implying a massive change in the star’s evolutionary course
Massive stars end their lives in supernova explosions, highly energetic events that can be as luminous as the entire starlight from their host galaxies. However, there are events called "supernova impostors“ which, despite their intensity, are not the end of the star’s life. This could very well be the case of SN 2015bh, a star which had suffered at least 21 years of violent eruptions and which, together with a number of other objects, could be a member of a new class.
Stellar formation shoots are observed in a type of galaxy where, in theory, stars are no longer born
January 19th 2017
CALIFA project allowed to detect, in three early-type galaxies, a very tenuous arms where stars are being formed.
The data, obtained with Calar Alto Observatory 3.5m telescope, contradict the widespread belief that in old galaxies stars are no longer born.
A stellar burst reveals the formation mechanism of massive stars
November 14th 2016
An outburst from a massive star in formation produced due to the sudden intake of material coming from its accretion disk, has been detected for the very first time.
This discovery is the most solid evidence so far that high mass stars are formed through a similar process to that which gives rise to the low mass ones.
Stars with low mass, like the Sun, are formed from big fragments of clouds of gas and dust, which condense until a central object, or proto star, is formed, growing it up by absorbing gas from a surround disk, and expelling the surplus material through a couple of jets located on both poles. However, it was not known if the most massive stars, with tens of the Sun mass, are formed through the same mechanism. The study of an outburst detected on the massive star in formation NIRS 3, and published today in Nature Physics, has provided the most solid evidence that, in effect, all stars are formed the same.
