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Post Info TOPIC: HL Tau
Blobrana


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RE: HL Tau
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Title: On planet formation in HL Tau
Author: Giovanni Dipierro, Daniel Price, Guillaume Laibe, Kieran Hirsh, Alice Cerioli, Giuseppe Lodato

We explain the axisymmetric gaps seen in recent long-baseline observations of the HL Tau protoplanetary disc with the Atacama Large Millimetre/Submillimetre Array (ALMA) as being due to the different response of gas and dust to embedded planets in protoplanetary discs. We perform global, three dimensional dusty smoothed particle hydrodynamics calculations of multiple planets embedded in dust/gas discs which successfully reproduce most of the structures seen in the ALMA image. We find a best match to the observations using three embedded planets with masses of 0.2, 0.27 and 0.55 MJ in the three main gaps observed by ALMA, though there remain uncertainties in the exact planet masses from the disc model.

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Blobrana


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HL Tauri
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Planet formation captured in photo

The clearest ever image of planets forming around an infant star has been taken by the Alma radio telescope.
In a vast disc of dust and gas, dark rings are clearly visible: gaps in the cloud, swept clear by brand new planets in orbit.
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Blobrana


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RE: HL Tau
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Title: Enhanced Dust Emission in the HL Tau Disc: A Low-Mass Companion in Formation?
Authors: J. S. Greaves, A. M. S. Richards, W. K. M. Rice, T. W. B. Muxlow

We have imaged the disc of the young star HL Tau using the VLA at 1.3 cm, with 0.08" resolution (as small as the orbit of Jupiter). The disc is around half the stellar mass, assuming a canonical gas-mass conversion from the measured mass in large dust grains. A simulation shows that such discs are gravitationally unstable, and can fragment at radii of a few tens of AU to form planets. The VLA image shows a compact feature in the disc at 65 AU radius (confirming the `nebulosity' of Welch et al. 2004), which is interpreted as a localised surface density enhancement representing a candidate proto-planet in its earliest accretion phase. If correct, this is the first image of a low-mass companion object seen together with the parent disc material out of which it is forming. The object has an inferred gas plus dust mass of approximately 14 M(Jupiter), similar to the mass of a proto-planet formed in the simulation. The disc instability may have been enhanced by a stellar flyby: the proper motion of the nearby star XZ Tau shows it could have recently passed the HL Tau disc as close as ~600 AU.

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Blobrana


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Astronomers see 'youngest planet'
 
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Blobrana


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An embryonic planet detected outside our Solar System could be less than 2,000 years old, astronomers say.
The ball of dust and gas, which is in the process of turning into a Jupiter-like giant, was detected around the star HL Tau, by a UK team.

_44533066_taumap226.jpg
Radio emissions from the HLTau system show the planet

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Blobrana


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HL Tau B
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"We really were amazed to see this, as it wasn't actually what we set out to do. We had an inkling that by looking for dust grains which are actually rocks the size of your fist we could see if rocks were coming together around the star to form a planet. But this was much further out than where we expected to find anything it is twice as far away from its star as Neptune is from the Sun. What it highlights is that other planetary systems must be amazingly diverse. It tells us that we shouldn't be too narrow minded when we are searching for a star that could have an Earth-like planet near it. The environments could be very very different, and we have to think about how this affects these solar systems" - Dr Jane Greaves, St Andrews University.

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Blobrana


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HL Tau
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As young stars form and evolve they generate spectacular high-speed jets and outflows consisting of molecular and atomic gas streaming away from the star. It is not completely understood what mechanisms launch these jets. This is partly because most of the action takes place in the inner, difficult to view, regions of the dense gas and dust accretion disk surrounding these forming stars. The best spatial and spectroscopic resolution is needed to dissect this region. A team led by Michihiro Takami (Subaru Telescope, now at ASIAA) and Tracy Beck (Gemini Observatory) have used the adaptive optics fed integral-field spectrograph NIFS on Gemini North to explore the inner structure of the jet in the young star HL Tau, located about 140 parsecs (460 light years) away in the constellation of Taurus.

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Position(2000): RA 04 31 38.4 Dec 18 13 59
Spectral type: K7e

HL Tau.kmz
Google earth file

-- Edited by Blobrana at 15:20, 2008-01-12

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