Emission nebula NGC 6357 and rich open cluster Pismis 24

Image credit: APOD The most prominent star of the open cluster Pismis 24 (top) is another object thought at one time to have several hundred solar masses, but now known to be at least a triple system – one where the components are each a hundred Suns. Wikipedia has a list of the most massive stars. Top of the list are the stars in R136 in the Large Magellanic Cloud, and at the bottom is the extreme red supergiant VY Canis Majoris (right), which can be seen undergoing copious mass loss.


I have drawn attention to the black hole firewall paradox previously, and Scientific American has an article, highlighting new work which argues for the reality of the paradox:

Polchinski and his colleagues conclude that not only is space not smooth at a black hole horizon—at that point the laws of physics completely break down. Instead of an unobtrusive boundary, the scientists argue that there must actually be a sharp division they call a firewall. “The firewall is kind of a wall of energy—it could be the end of spacetime itself,” Polchinski says. “Anything hitting it would break up into its fundamental bits and effectively dissolve.”

A full treatment of the subject is here, and dissenting arguments can be found here. If the new paradigm proves true, the event horizon will be seen as the place where the laws of physics break down, not the singularity itself.


In addition, there are a pair of new brown dwarf discoveries, not yet peer-reviewed but by leading authors in the field. In the first, overseen by Prof. S.J. Warren at Imperial College, the largest homogeneous sample of ultracool dwarfs to date has been assembled, and appears to have increased the number of known L dwarfs enormously. This has been accomplished by mining existing surveys (SDSS, UKIDSS and WISE) down to apparent magnitude J = 17.5. In the second paper, a bizarre underluminous M dwarf – that is, an extreme M subdwarf – appears to have been found with a large proper motion of 1.8 arcseconds per year, in the WISE dataset. The distance is, however, uncertain.

Update: The 25 year Lick planet search, using the Hamilton spectrograph, has been completed and a homogeneous dataset released:

The Lick Observatory planet search program began in 1987 when the first spectrum of τ Ceti was taken with an iodine cell and the Hamilton Spectrograph. Upgrades to the instrument improved the Doppler precision from about 10 m/s in 1992 to about 3 m/s in 1995. The project detected dozens of exoplanets with orbital periods ranging from a few days to several years. The Lick survey identified the first planet in an eccentric orbit (70 Virginis) and the first multi-planet system around a normal main sequence star (Upsilon Andromedae).


Lick will continue at the forefront of exoplanet research with the new robotic Automated Planet Finder (APF). The practice of using the spectrum of an arc lamp as a wavelength comparison has a long history. Above is the high resolution visible spectrum of the Sun, showing numerous absorption lines, strong and weak. Image courtesy W.M. Keck observatories.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: