astrophysics – Wis[s]e Words

Sensawunda

Published on June 27, 2010

Centauri Dreams on the increasingly many brown dwarf stars that are being found in our stellar neighbourhood and how cool they are:

In fact, it gives me pause to reflect that the focaccia I baked the night before last needed higher temperatures (500 degrees Fahrenheit) than the coolest of these brown dwarfs can supply. Most of the new objects in the Spitzer study are T dwarfs, the coolest class of brown dwarfs known, defined as being less than 1500 Kelvin (1226 degrees Celsius). One of the dwarfs in this study is cold enough that it may represent the hypothetical class called Y dwarfs, part of a classification created by a co-author of the paper, Davy Kirkpatrick (Caltech).

Brown dwarfs may be the most common stellar objects around as this representation shows. You wonder if brown dwarfs could have planets and if so, whether those planets could have life on them and if so, how it’s adapted to the extremely cold temperatures such planets must suffer from. Of course, from a hypothetical intelligent species arising on a planet around a brown dwarf, we ourselves would be exotic extremophilic lifeforms: imagine being able to exist at temperatures where water is a liquid!

A beautiful day in the neighbourhood

Published on August 5, 2009

So won’t you be my neighbour?

The Solar Neighbourhood

The nearest stars to us, within a range of fifteen lightyears. For the time being that is, as don’t forget we’re all in our separate orbits around the Galaxy. Essential knowledge for any science fiction writer who wants to keep some semblance to reality. As is this, an exploration of the solar neighbourhood up to sixtyfive lightyears out. Via James, of course.

The State of the Universe – Pedro G. Ferreira

Published on May 7, 2009

Cover of The State of the Universe

The State of the Universe
Pedro G. Ferreira
320 pages including index
published in 2006

I felt the need to reacquaint myself with modern astrophysics as it has been far too long since I’ve read anything about it. Sure, I do watch The History Channel’s Universe series whever I catch it, but that doesn’t tell me much I don’t know already, while following the vast array of astronomy blogs out there is no real substitute, as they do assume a certain familiarity with the current state of the art. Long live the public library therefore, for providing quick access to what looks like exactly the book I need: The State of the Universe: a Cosmic Primer. Written by Pedro Ferreira, a lecturer in Astrophysics at Oxford, it’s meant as a layperson’s introduction to what astrophysics thinks the universe looks like and what makes it tick.

The State of the Universe is built up logically from first principles. Ferreira starts with a short overview of classical Ptolemaic cosmology, with the Sun revolving around the Earth and how it was succeeded by the heliocentric cosmology of Copernicus and Gallileo. Over several chapters he then shows how our knowledge of the size and complexity of the universe expanded, from what was once thought to be no bigger than our Solar System, through an understanding of how big our Galaxy actually and finally to an appreciation of the idea that all those galaxy shaped nebulas are actually galaxies as well. Then he goes on to the other end of the scale and explains the physics of the universe: the fundamental forces that shape it (gravity, electromagnetism, the strong and weak force), a quick sketch of the whole zoo of the particles that make up the matter and energy in it and how it all sits together. From the classic Big Bang idea of the evolution of the universe he finally moves on to the cutting edge of current physics, where it all gets a lot less clear what’s real and what’s just clever theorising.