Fri, 25 May 2007
Outflows have been discovered from a Brown Dwarf star, 2MASS1207-3932, the lightest yet.
Found by Emma Whelan and Tom Ray of DIAS and others , using the ESO's Very Large Telescope (VLT), this is the first time that Jets have been seen from an astronomical object as small as this.
The Brown Dwarf is 2MASS1207-3932, a 24-Jupiter mass 'near star'. Jets of material are a common feature in astrophysics, seen from Galaxies and young stars, but this is the first time they have been seen in something this small. It opens the possibility of similar outflows from smaller objects, such as giant planets.
The brown dwarf 2MASS1207-3932 is full of surprises. Its companion, a 5 Jupiter-mass giant, was the first confirmed exoplanet for which astronomers could obtain an image, thereby opening a new field of research - the direct detection of alien worlds. It was then later found that the brown dwarf has a disc surrounding it, not unlike very young stars.
Thu, 19 Apr 2007
As a followup to the talk given at Galway Astrofest 2007 by Dr. Aaron Golden on work done by the Cool Stars research Group here at NUIG, the detail of this work were announced this week at the RAS National Astronomy Meeting 2007. Other press releases can be found at Spaceflight Now, and NRAO, though the best summary is probably at the NUIG Webpage (Thanks to Ronan Newman for the links). Kudos to all involved: Gregg and Stephen are currently writing up their PhDs and should have an interesting dissertions from this.
Basically, they discovered that some Brown Dwarfs can act as Pulsars, blasting out huge amounts of radio-wave energy. Brown Dwarfs are objects between 'Planet' and 'Star' in mass terms, often thought of as boring failed stars, not large enough to ignite into fusion. They were thought by most to be highly boring : this discovery was completely unexpected.
As the group in Galway has a lot of pulsar experience, they were well set to explain this. It looks as though this phenomena is due to a 'coherent maser' : an effect seen in large planets such as Jupiter, where the magnetic field spins up electrons from a solar wind. Certainly, it makes Brown Dwarfs, undiscovered until 1994 but thought to be widespread across the universe, more interesting things to look at.
Sun, 11 Feb 2007
I went to the Astronomy Festival on Jan 27 organised by Galway Astronomy Club. Worth seeing; it attracted about 100 people (the Hotel conference room was full); successful for a town like Galway, so frequently covered in Cloud.
Dr. Lucie Green save a good talk on Solar Physics, describing the different methods we now have of exploring the Suns behaviour, Flares, Sunspots, etc. and the different missions such as SOHO and the new STEREO mission to observe the Sun.
Prof. Chris Dainty gave a clear presentation describing the state of the Art in Adaptive Optics, and work his group has been doing, both in Astronomy and pushing AO into other fields, such as opthalmology (treating the eye as the obstacle and observing the retina behind) and productising A.O. for 'non-professional' use. He hopes in the near future to be able to provide Adaptive Optics to Amateurs (price range around Eur 5000, status: not ready yet, the first units would be for 'University Dept' observatories, costing 20-30k, in the next year or two).
Of particular interest were one by Prof. Dick Butler, head of the Chemistry dept. here in NUIG; it was on Organic Chemistry and meteorites. He is a long-time amateur astronomer but professional chemist; he was particularly interested in the organic chemistry of the Murchison meteorite. After pointing out the out the false alarm of ALH 84001, he gave a convincing presentation of the extra-terrestrial origin of complex organic compounds, including amino acids, etc. in the Murchison meteorite. In particular he disputed claims that the meteorite was contaminated, pointing to the Deuterium enrichment of the compounds within; as the C-D bond is stronger that C-H, Carbon-Hydrogen compounds are more likely to be broken up by extraterrestrial radiation that their deuterium variants, leading to deuterium enrichment over terrestrial equivalents. Later he gave a nice summary of conditions on Saturn's moon Titan, pointing to its rich supply of organic compounds, showing that when hit by meteorites, lakes of water would be possible for several hundred years at a time, as the impact craters cooled, and called Titan a utopia for organic chemistry exploration.
This seems to make the idea of panspermia: life originating off-Earth more plausible. For a while now I've had a book (found in the Bargain bin somewhere) by Fred Hoyle and Chandra Wickramasinghe, From Grains to Bacteria, a collection of papers documenting their belief that they've discovered bacteria in free space via spectroscopy. I must admit my spectroscopy is not up to challenging them; time to dig deeper and fish it out.
Dr. Aaron Golden gave a very interesting talk on Brown Dwarfs: Planets or Pulsars that he and his students have been doing. Basically it turns out that while Brown Dwarfs have long been seen as the 'runt' of the Stellar world, stars that didn't make it, some of them it seems are Pulsars. (He's invented the acronym SPUDs: Sporadically Pulsating Ultracool Dwarfs, for them; maybe it'll help people remember that Pulars were originally discovered by an Irishwoman, too).
This was first seen by Aarons' Postgrads Greg Hallinan and Steve Bourke - (see the papers). Kinda interesting as Aaron studied under Dr. Andy Shearer in NUIG working on Pulsars, so knew a bit about them, and had seen behaviour like this before, with a bit of a clue what might be causing it. It was wierd going to this talk; Andy hired me to work in ICHEC, and we have an office in NUIG; Greg and Steve work down the hall, and indeed, I see them occasionally working on our computers; but didn't know what they'd been working on until now.
So, it appears that these Brown Dwarfs (they've seen Pulsar behaviour in several) have Starspots (details here and here; some hot-off-the-press stuff: rumour has it he was checking the results of observations from the night before to ensure they didn't disprove what he was about to say). Aaron was pointing out the coherent maser behaviour was similar to that seen at Jupiter, leading to its strong radio emissions. I didn't get to talk to him about it in detail, but the idea of an Object with both sunspots and clouds sounds fairly exotic and interesting.
Beyond that, the Festival was a good opportunity to see what Irish Amateur Astronomers have been doing, and meet some interesting people. Kudos to all those who organised it.