The Next New Meteor Shower

My latest at Sky and Telescope

Astronomers confirm that debris from Comet 209P/LINEAR should create a sky show on May 24, 2014.

According to predictions, a little-known comet will pass perihelion in early May of 2014 and, two weeks later, sandblast Earth with dust particles spread along its orbit

Most meteor showers, like this week’s Leonids, occur when Earth plows into the debris trail left behind by a comet. The comet throws this debris off as it’s heated by the Sun, but while all comets heat up as they enter the inner solar system, many do not have orbits that intersect with Earth’s. That’s why the number of major meteor showers per year has remained relatively constant, even though we’re regularly discovering new comets.

The tried-and-true list of showers might change soon, though. As we noted in 2012, the comet 209P/LINEAR, which passed by the Sun in 2009, may produce a big meteor shower on May 24, 2014. New calculations by Quanzhi Ye and Paul A. Wiegert (both University of Western Ontario) refine that prediction — and make it a little less optimistic.

Mind the Gap

My latest at Sky and Telescope

One Gap, No Planets

Where’s the planet that should be to blame for this star’s carved-out disk?

This illustration shows a young star with its dusty disk, in which a gap has been carved out. Astronomers think such gaps signal the formation of planets.

 

How do planets form? This deceptively simple question has sparked a new field in astronomy over the last two decades. Astronomers have used telescopes all over the world (and in orbit!) to study all stages of planet formation, from disks of material around infant stars to the scattered debris and planetesimals in systems such as Fomalhaut’s. The goal of all these studies is the development of a coherent scenario that explains the behavior and evolution of planet-forming disks around young stars and links them to the exoplanets observed around older stars (such as those glimpsed by Kepler).

Click here to read the whole article.

A Stellar Senior Citizen

Here’s my latest at Sky and Telescope:

“The search for the oldest stars in the Universe has just turned up a new candidate: HD 140283. This 7th-magnitude sub-giant has intrigued astronomers for decades. It was one of the first stars found with an extremely low concentration of heavy elements in its outer atmosphere, compared with the Sun. And this composition makes the star — which has roughly the same temperature as the Sun — look like a star twice as hot as it is. 

Now, Howard Bond (Space Telescope Science Institute and Penn State) and his colleagues have confirmed that HD 140283 may be one of the first stars born after the Big Bang, they report in the March 1st Astrophysical Journal Letters.”

Site News

Hi All

I haven’t updated this page in a while, but I have been busy blogging at Sky & Telescope.  For the time being, I will link my new posts from that site here, until I can find a more suitable solution.

 

Here are the latest articles:

Four Mammoth Cameras Take on the Sky

Auroras Grace Stellar Skies

A New Goldilocks Planet

Making Mini-Oort Clouds

 

The First Stars in the Universe

Star formation is one of the great unsolved problems in astronomy.  It is very difficult to simulate the star formation process with a computer mainly because it is a problem that spans many orders of magnitude in size, temperature and pressure, and must incorporate a variety of chemical processes. More simply put, there are hardly any spots to make approximations.  But solving star formation is still very important, because without stars, you wouldn’t be sitting here reading this blog today.  When massive stars explode (or supernova) they seed the space around them with heavy elements, such as the iron in your blood.  These explosions also help future generations of stars form.  Understanding how star formation works today keeps a lot of astronomers (both theorists and observers) very busy, but some astronomers like a challenge.  These astronomers study the first stars to ever form.

Squishing a Neutron Star

The final end products of stars are really extreme. Stars like the Sun end up as “white dwarfs”, where the exposed core of the former star is left behind, and about 60% of the total mass of the star is jammed into something the size of the Earth. A spoonful of a white dwarf would weigh about 1 ton (here on earth). Stars much more massive than the Sun end their lives as black holes. Good luck getting a black hole on a spoon. Its gravitational force would be so intense, the molecules that compose the spoon, your hand, and your arm would be shredded apart. In between black holes and white dwarfs are objects called neutron stars. They are much more dense than white dwarfs. One spoonful of a neutron star would weigh about 1 billion tons. Which raises some interesting questions.

Tiny Particles, Big Equations

Sorry for the delay. I’ve been busy and neglecting my blogging duties. -John

Astronomy basically proceeds in one of two ways. Observers (like me) go out and use telescopes to record positions and brightnesses on the sky. We take that data and compare to models that theorists produce that allow us to infer what is going on at the source of the light that we record. In a paper titled “Neutrino Spectra from Accretion Disks: Neutrino General Relativistic Effects and the Consequences for Nucleosynthesis” by O.L Caballero, G.C. McLaughlin and R. Surman, the authors make theoretical predictions for the behavior of protons, neutrons and neutrinos in the accretion disks around black holes.

The Universe’s Biggest Explosions

Everyday, there are a few explosions ripping through distant galaxies that produce enough energy in a few seconds to power the Sun for its entire lifetime. Or in more terrestrial terms, these explosions are as powerful as 10,000,000,000,000,000,000,000,000,000,000,000,000 100 watt lightbulbs. Yet, no one knew about them until the 60s. Even then, they weren’t detected by astronomers, but by U.S. satellites designed to sniff out Soviet nuclear testing. It wasn’t until the late 90’s that they were studied in large numbers. Now, with data coming from the Swift satellite, astronomers have started to more fully understand what may be causing these large explosions.

Black Holes, Disks and All that Stuff

Black holes are the powerhouse of galaxies. They are typically millions of times more massive than the Sun, yet occupy no space at all (this is a topic for an entire other post). Black holes exert a tremendously large gravitational pull, since gravity is the strongest for massive, small objects. One common misconception about black holes is that they suck material in. This just isn’t the case. If the Sun were replaced with a black hole with the same mass, the Earth would happily orbit this black hole without being pulled in (of course, the lack of sunlight would be bad for all life on Earth). For the most massive black holes, found in the center of many galaxies, there is nearby gas and dust that orbits the black hole at very close distances. This structure is known as an “accretion disk”, since the matter within the disk eventually falls into the black hole.

Some site news

First off, I am planning to ramp up the frequency of my posts. So look for a new article at least every two weeks, and possibly more often if I can recruit some help in this little venture.

Second, in a act of blatant self-promotion, please check out the this article at space.com, which highlights some of my own work that was presented at the last major astronomy convention in Seattle, Wa in Jan 2011. Perhaps when this work is posted to the ph, I will link to it.

Third, if you like this blog (and have actually found it), you’ll also be interested in Astrobites. This is a great blog put together by a few Harvard grad students that does something very similar to my own site. They summarize current ph articles for undergrads astronomy majors. If you’d like just a sample of their work, I’d recommend this article.