March 2009: Quasars

In this episode we find out about supermassive blackholes in the early universe from Professor Marco Spaans, we encourage you to hold star parties and other events during the 100 Hours of Astronomy, we get the latest news and find out what to see in the night sky during March.

The News

In the news this month:

• Gamma ray bursts (GRB) are enormously energetic events thought to be signatures of massive stellar explosions in distant galaxies. On September 16th 2008, a spectacular event was recorded by the Gamma-ray Burst Monitor on the FERMI gamma ray satellite. FERMI searches for these events using sensitive instruments and surveys the sky looking for high energy emission from other interesting objects. Located in the southern constellation Carina, the burst - GRB 080916C - was quickly observed with other telescopes on the ground. A team using the 2.2m telescope at La Silla in Chile calculated that the object was at a redshift of 4.35; a distance of 12.2 billion light years. Analysis of the results show that this burst is the most energetic observed to date.
• Exactly how galaxies form has been a topic of debate for some time. Research published in Nature has found evidence that star forming regions in young galaxies are small but forming stars at astonishingly high rates. A team used the IRAM interferometer to study a distant galaxy - J1148+5251 (PDF) - to search for the highly redshifted signal of ionised carbon. They found that the star formation was concentrated in the central 750 parsecs (about 2450 light years) of the galaxy and was 1000 greater than in the Milky Way.
• Orbiting around large galaxies are dwarf galaxies. A study of gas in the Leo Ring by the Galaxy Evolution Explorer (GALEX) has found a collection of very unusual dwarf galaxies forming in a way that has not previously been seen. The Leo Ring is a huge cloud of mainly hydrogen and helium gas surrounding the galaxies M105 and NGC 3384 in the constellation of Leo. The cloud - seen in radio waves but not in optical light - contains a mass of hydrogen almost 2 million times the mass of the Sun. The GALEX observations have shown that star formation has been forming recently within the ring.
• At 4:56am on February 10th an active communications satellite and a retired Russian military satellite collided at a relative velocity of 10 km per second over Siberia, simulations (WMV) show that the collision released 50 kJoules of energy per gram. The collision created over 600 pieces of space debris that are large enough to be tracked from the ground. This has increased the chances of a collision during the planned Hubble servicing mission.

Interview

Nick talked to Marco Spaans (University of Groningen) about quasars - specifically, the first quasars in the universe and what they can tell us about galaxy formation and evolution. Marco also describes how quasars are observed at a variety of wavelengths, including in the sub-mm, using the Atacama Large Millimetre Array (ALMA).

100 Hours of Astronomy

Between 2-5 April, as part of the International Year of Astronomy, people all around the world will be participating in the 100 Hours of Astronomy. If you are organising an event or star party, you can register your event on a global map.

The Night Sky

Ian Morison tells us what we can see in the night sky during March 2009.

Northern Hemisphere

We have a wonderful sky-scape centred on Orion and that has been discussed last month and the month before. To the lower left of Gemini, in the south east at about 10pm, is the constellation of Leo. The question mark shape of the head drops down to the star Regulus. To the lower left of Leo is the constellation of Virgo. There isn't a lot to see by eye but between the tail of Leo and Virgo is the realm of the galaxies. Moving up towards the north we reach Ursa Major or the Great Bear. We tend to only talk about The Plough (The Big Dipper) which is a very nice part of the sky. The two right-hand stars of the Plough are the Pointers and point up towards the north star. If you look at the second star to the end of the tail with binoculars you'll see that it is in fact a double star. With a small telescope you will see that the brighter of those two stars is also a double star.

Jupiter is still very low. On March 22nd Jupiter will be to the left of a waning crescent Moon and on March 23rd it will be to the right. Saturn is one of the best placed planets in the sky rising at around 7.30pm at the start of the month and at sunset by the end of the month. It is sitting below Leo. Mercury is moving away from us this month and will be on the far side of the Sun (superior conjunction) on the 31st March. There is just a chance to spot it at the very beginning of the month before dawn. It will be very low (~2 degrees) above the horizon and seen down to the lower left of Jupiter but, to be honest, its probably not worth it. Mars is still close in angle to the Sun (just 21 degrees as March begins) so will be very hard to spot in the pre-dawn sky having a magnitude of 1.2. By the end of the month the angular seperation has increased to 28 degrees which helps, but as the ecliptic makes such a small angle to the horizon that Mars will be just 4 degrees above the horizon as the Sun rises. We will have to wait a month or so until it will be seen easily in the pre-dawn sky. Venus has been dominating the western sky after sunset for the last few weeks and can still, as March begins, be seen high in the west after sunset shining at magnitude -4.5 so can hardly be missed! Venus will be seen lower in the sky week by week and by the 20th will start to become hard to spot in the glare of the Sun. It will lie between us and the Sun (called inferior conjunction) on March 27th so will be invisible for some time before reappearing in the pre-dawn sky around the 5th of April.

Highlights

• Comet Lulin can still be seen with binoculars moving from Leo into Cancer.
• As the ecliptic in the evening is inclined at a high angle to the horizon, it gives us a chance to see a very thin crescent Moon just 27 hours after New Moon on March 27th. It will be around 6 degrees above the horizon in the west at around 6.30 pm.

Southern Hemisphere

In the north in the early evening you can see Orion, Gemini and Taurus. Below Gemini you might just see the bright star Capella in the constellation of Auriga just above the horizon. To the lower left are the Hyades and Pleiades open clusters in Taurus. Rising up from the southern horizon is a beautiful part of the Milky Way coming up through Centaurus, Carina and Vela. Over to the left is Omega Centauri that is thought to be the remains of a galaxy that had its outer parts stripped off by gravitational interactions with our own Milky Way.

Odds and Ends

Mike Van Vooren and EarthUnit point out the Atlas of the Universe. On the Forum there is a discussion about favourite Jodcast interviews.

Show Credits