Hubble optical image (left) and VLT infrared image (right) of the circumstellar disk surrounding HD 100546. (ESO/NASA/ESA/Ardila et al.) |
Excerpt from news.discovery.com
Mommy, where do baby planets come from? There’s no storks, birds, bees, or romantic dinners for two involved in the answer to that question — regardless of size, planets are all formed in pretty much the same way: through the aggregation of material within the disk of dust and gas surrounding a young star. While how long it actually takes and just what sort of planets are most likely to form where are still topics of discussion among astronomers, the birth process of a planet is fairly well understood.
And this may be the very first image of it actually happening.
Acquired by the European Southern Observatory’s Very Large Telescope (VLT), the infrared image above (right) shows a portion of the disk of gas and dust around the star HD100546, located 335 light-years away in the constellation Musca. By physically blocking out the light from the star itself by means of an opaque screen — seen along the left side of the image — the light from the protoplanetary disk around HD 100546 can be seen, revealing a large bright clump that’s thought to be a planet in the process of formation.
If it is indeed a baby planet, it’s a big one — as large as, or perhaps even larger than, Jupiter.
This does raise an interesting question for astronomers because if it is a Jupiter-sized planet, it’s awfully far from its star… at least according to many current models of planetary formation. About 68 times as far from HD100546 as we are from the sun, if this planet were in our solar system it’d be located deep in the Kuiper Belt, twice as far as Pluto. That’s not where one would typically expect to find gas giants, so it’s been hypothesized that this protoplanet might have migrated outwards after initially forming closer to the star… perhaps “kicked out” by gravitational interaction with an even more massive planet.
Alternatively, it may not be a planet at all — the bright blob in the VLT image might be coming from a much more distant source. While extremely unlikely, further research will be needed to rule that possibility out.
If it’s found to be a planet, HD100546 “b” would offer scientists an unprecedented opportunity to observe a planetary formation process in action — and from a relatively close proximity as well.
According to the team’s paper, submitted to Astrophysical Journal Letters, ”What makes HD100546 particularly interesting is that 1. it would be the first imaged protoplanet that is still embedded in the gas and dust disk of its host star; and 2. it would show that planet formation does occur at large orbital separations.”
(Now all we have to do is wait a couple billion years and then show these pictures to HD100546b’s girlfriend. How embarrassing!)
Meteorite is ‘hard drive’ from space ~ Researchers decode ancient recordings from asteroid ~ BBC
Like the data recorded on the surface of a computer hard drive, the magnetic signals written in the space rock reveal how Earth's own metallic core and magnetic field may one day die.
The work appears in Nature journal.
Using a giant X-ray microscope, called a synchrotron, the team was able to read the signals that formed more than four-and-a-half billion years ago, soon after the birth of the Solar System.
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Dr James Bryson University of CambridgeThe new picture of metallic core solidification in the asteroid provide clues about the magnetic field and iron-rich core of Earth.
Core values "Ideas about how the Earth's core evolved through [our planet's] history are really changing at the moment," lead researcher Dr Richard Harrison, from the University of Cambridge, told BBC News.
"We believe that Earth's magnetic field is linked to core solidification. Earth's solid inner core may have started to form at very interesting time in terms of the evolution of life on Earth.
"By studying an asteroid we get to see this in fast forward. We can see the start of core solidification in the magnetic records as well as its end, and start to think about how these processes work on Earth."
Tiny particles, smaller than one thousandth the width of a human hair, trapped within the metal have retained the magnetic signature of the parent asteroid from its birth in the early Solar System.
"We're taking ancient magnetic field measurements in nano-scale materials to the highest ever resolution in order to piece together the magnetic history of asteroids - it's like a cosmic archaeological mission," said Dr James Bryson, the paper's lead author.
"Since asteroids are much smaller than Earth, they cooled much more quickly, so these processes occur on a shorter timescales, enabling us to study the whole process of core solidification."
Prof Wyn William, from the University of Edinburgh, who was not involved in the study, commented: "To be able to get a time stamp on these recordings, to get a cooling rate and the time of solidification, is fantastic. It's a very nice piece of work."
The key to the long-lived stability of the recording is the atomic-scale structure of the iron-nickel particles that grew slowly in the asteroid core and survived in the meteorites.
Making a final comment on the results, Dr Harrison said: "In our meteorites we've been able to capture both the beginning and end of core freezing, which will help us understand how these processes affected the Earth in the past and provide a possible glimpse of what might happen in the future."
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