Elementary Astronomy News Highlights

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Each week in 107-02 we will discuss something interesting that has been in the news. The subjects will be drawn from the New York Times, [http://apod.nasa.gov/apod/ Astronomy Picture of the Day], and press releases from NASA, the European Space Agency, the European Southern Observatory, or the Space Telescope Institute. If there is something interesting from one of our telescopes we may tell you about that too. This page has the highlights.

Week of January 16, 2012

The New York Times and Nature reported the discovery of more planets orbiting two stars. Like the fictional Tatooine of Star Wars there would be two "suns" in the sky if you could stand on them and look up. However, these new discoveries are the size of Saturn, and they are so close to their stars that they are too hot to be habitable.

The first planet found orbiting two stars was Kepler 16. The Kepler telescope finds planets by capturing the moment when they pass between us and their stars, blocking out a tiny fraction of the star's light (often less than 0.1%). These events allow astronomers to measure the size of the orbit, the diameter of the planet, and in some instances even the planet's atmosphere. For Kepler 16 the data look like this:

Kepler16 transits.jpg
A planet in orbit around another star may block off light from the star for a few hours every time it goes around.
L. Doyle et al., Kepler-16: A Transiting Circumbinary Planet in Science 333, 1602-1606 (2011)

A planet like Earth is at just right distance -- in the Goldilocks zone -- where life such as we know it can flourish. Other known planets are usually either too close to their star(s) and too hot, are too far away and too cold.

Kepler16 system.jpg
Kepler 16 and other recently discovered planets orbit two stars.
L. Doyle et al., Kepler-16: A Transiting Circumbinary Planet in Science 333, 1602-1606 (2011)

Week of January 9, 2012

The science journal Nature reported the discovery made at the Very Large Telescope of the European Southern Observatory of a cloud of gas that is on a trajectory to fall into the million-solar-mass black hole at the center of the Milky Way. Click this link to see what they had to say.You may have to be connected through the University of Louisville's network to read the full article.

Nature Volume 481 Number 7379 pp5-108

A gas cloud has been spotted approaching the Milky Way's central black hole. Observations of its closest approach, expected to occur in mid-2013, may offer insight into the black hole's immediate surroundings.

Credit: ESO

The discovery was also described in the New York Times with the headline Black Hole Forecast: A Cold Gas Cloud

The center of the Milky Way is a site known as Sagittarius A*, or SgrA* for short. You can watch a short video about this here:

YouTube: ESO Discovery of gas near the center of our galaxy