Big baby found

One of the hottest debates in star formation at the moment centres around giant stars and how they form. We know that stars up to and maybe beyond one hundred and thirty times the mass of the Sun exist, but theoretically dealing with their formation is a bit of a disaster. Stars above about ten solar masses burn their fuel rather quickly, leading to short lifespans and massive luminosity. They get so bright, in fact, that when dust and gas fall in during their earliest times, theory says the pressure of their outward radiation should blow away the dust, preventing them from getting any bigger.

Alternate explanations for how they might grow to the sizes seen include merging between stars in tightly packed clusters and funnelling of material through magnetic fields intersecting with the star, or through non-spherical infall geometries, with more stuff coming in at certain points than others. Now the first observation of a massive star in the process of formation has been made and it shows – a dusty disc.

IRAS 13481-6124 is located about 10,000 light-years away in the constellation Centaurus. It is around twenty solar masses and has a dust disc that is elongated, stretching thirteen times the Earth-Sun distance in one direction and nineteen times along the other, suggesting a disc seen at an angle of around forty-five degrees. It stops nine and a half times the Earth-Sun distance from the star, similar to such discs seen around lower mass stars in formation. There are indications of jets coming from the poles of this object, suggesting a process of ongoing accretion. Observations of the object were carried out at ESO‘s Very Large Telescope Interferometer, which combined the light from several near-infrared telescopes to form a higher resolution image than could be got from any of the individual telescopes involved.

The resulting paper was published in Nature. The editor of Nature puts a summary here and another blog’s take on the story is here.

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