Astronomy news

Ceres and Vesta - a foretaste to a visit by the Dawn spacecraft

Astronomy and Astrophysics journal is publishing a study of the orbital evolution of minor planets, including asteroids such as Ceres and Vesta, in the lead-up to the visit by the Dawn spacecraft. It seems that the earth's past orbit cannot be reconstructed beyond 60 million years ago, it is claimed. In other words, the past orbit of the earth is open to conjecture and it is not as cut and dried as uniformitarianism would have us believe.

Black Holes

At www.physorg.com/print229767192.html there is some speculation about the origin of black holes. They were not formed by mergers between galaxies as hypothesised elsewhere, it says. They are mostly found in massive galaxies with lots of dark matter, it is alleged, and continues by saying they are absent in galaxies of moderate mass. The information is derived from space telescopes and cameras and is published in the Astrophysical Journal and represents an attempt to explain why some galaxies have extremely bright features, evidence of activity, and others are less bright.

The Sun ... dark fireworks

This story is at a variety of sites but www.physorg.com/print229686172.html is as good as most. On June 7th this year, 2011, a flash of X-rays was registered with an origin in the Sun - but was fairly moderate as these things go. However, when astronomers looked at the images taken by cameras on satellites circling the earth they were astonished at the intensity of the solar storm. A video and a smaller You Tube version is available online to view.

Dwarf Galaxies ... again

At www.dailygalaxy.com/my_weblog/2011/07/is-there-a-fundamental-flaw-in-our... is an interesting question - and it is all up for grabs. The bigger galaxies are supposed to form from a merger of smaller galaxies but the properties of dwarf galaxies do not seem to match this scenario. Eline Tolstoy from the University of Groningen in the Netherlands draws attention to this anomaly. Dwarf galaxies are the most straight forward objects astronomers can study as far as star formation is concerned.

Dwarf Galaxies

Pavel Kroupa of the University of Bonn, and colleagues, analysed the notion of dwarf galaxies, thousands of stars that orbit the Milky Way. These are apparently orbiting in a plane rather than being evenly distributed - which is a problem for calculations. These seem to show such small galaxies do not contain dark matter yet, observations of their orbital speed implies they should contain dark matter as the extent material is not enough to explain the velocities inferred.

A black hole ... Cygnus X1

At www.dailygalaxy.com/my_weblog/2011/06/cygnus-x-1-a-black-hole-harvard-sm... is one of those posts where you wonder if the use of proof is a bit stretched, but never mind, apparently some people think Hawking has lot a bet he made with Caltech astrophysicist Kip Thorn on Cygnus X1. Hawking said it was a neutron star and Thorn was sure it was a black hole. It seems Thorn has won himself a year's subscription to Penthouse magazine as astrophysicists claim to have measured the distance and mass of the star.

A trillion bolts of lightning

Yes, a trillion bolts of lightning are being emitted from what is said to be an enormous black hole in a distant galaxy (see www.dailygalaxy.com/my_weblog/2011/06/universes-highest-electric-current... ). Philipp Kraberg of the University of Toronto and some colleages say they have measured the alignment of radio waves around Galaxy 3C303 where a giant jet is shooting out of the centre. A sudden change in the alignment of waves coinciding with the jet was 'an unambigous signature of an electric current' he said.

More info on Mercury

At www.dailygalaxy.com/my_weblog/2011/06/-mercurys-messenger-reveals-surpri... (see earlier post a few days ago). This blog post is derived from information from the Carnegie Institute and it expands a little on what the Messenger spacecraft has found out about the magnetosphere of Mercury. The Mariner 10 fly by in 1974 witnessed a burst of highly energetic particles in the magnetosphere but nothing as powerful as that has been seen by the Messenger during its 3 fly bys so far. However, bursts of energetic electrons have been seen - which were not as energetic.

Upstairs ...

It seems that elliptical galaxies are not spherical as once thought but disc shaped and resemble spiral galaxies. This result came from Atlas 3D and was published in the Monthly Notices of the Royal Astronomical Society (in June) (see www.physorg.com/print227770886.html).

Odd Mercury

Mercury isn't a bit like it was supposed to be. NASAs Messenger spacecraft shows craters on the planet that are deep and cold enought to hold frozen water - but Mercury is the rock closest to the Sun. Images of other regions indicate large eruptions have taken place - which somehow they can date to 3.7 billion years ago. When journalists or press releases express these numbers with such certainty one can't help being amused - but then again someone must have fed them the information. Craters are in fact thought to be buried beneath the lava - or basalt floor of the planet.