Bakersfield Night Sky – February 15, 2014
By Nick Strobel
Last weekend a group of people from the Kern Astronomical Society gathered at a member's house to put together goody bags and create beautiful poster displays for the Astronomy Day that will take place on April 12th at the new Houchin Community Blood Bank at 11515 Bolthouse Drive. The event will be free. It will include a special speaker, Alex Filippenko, who will talk about dark energy and the accelerating universe. This dark energy is the astronomy kind, not something from Harry Potter or the like. Dark energy of the physical astronomy kind is a form of energy of empty space that makes up about 68% of the total universe's energy. It is responsible for making the expansion of the universe increase at a faster rate than before against the attractive force of gravity that would tend to slow the expansion rate down.
This acceleration of the universe's expansion was discovered in 1998 by two independent research teams who used a particular type of supernova explosion to measure distances to very distant galaxies. The type of supernova explosion astronomers like to use for distance measurements are called Type Ia (pronounced "type one A"). Astronomers like to use Type Ia supernovae because they are extremely luminous so you can see them from even billions of light years away and also because they all have about the same luminosity or power output. If you know something's luminosity or intrinsic brightness, you can determine its distance from how dim it appears in the same way you could measure a light bulb's distance if you knew that you were looking at a 100-watt bulb. A Type Ia supernova happens when an already dead compact star called a white dwarf orbiting near another star sucks up enough gas from its companion to explode.
Alex Filippenko happened to be on both of the supernova teams measuring the distances and speeds of distant galaxies and he can attest to the very competitive nature between the two teams. The leaders of the two teams were not fond of each other (I'm being diplomatic here) and therefore, were very eager to prove the other team wrong. The fact that two independent, highly-competitive teams found the same surprising result that was the opposite of their expectations meant that the accelerating universe conclusion could not be discounted. The leaders of the teams eventually got the Nobel Prize in Physics (in 2011) for their discovery and other teams have confirmed that the universe's expansion has been accelerating for the past several billion years. Dr. Filippenko will be able to talk about the accelerating universe from a first-hand researcher's perspective.
It just so happens that a Type Ia supernova went off in a neighboring galaxy to us, so the astronomy news wire has been abuzz about it. The supernova was discovered in late January by a group of astronomy students at the University of London Observatory (within the London city limits). The supernova went off in Messier 82, a starburst galaxy "only" 11.5 million light years away. As of last weekend, it was still bright enough that it could be seen with a normal amateur telescope under the Bakersfield skies, though it has dimmed from its peak. It is the nearest Type Ia supernova to happen since 1972. Having a supernova of the type used for measuring the universe happen so close to us when we now have many space-based observatories able to probe our assumptions of how these objects behave makes this quite a special event. Other supernova have been observed in M82 and its neighbor, the large spiral galaxy M81, but they have been the type that happen when a massive star's core implodes and the resulting shockwave blasts the outer layers outward to space. Supernovae of the massive star death type are described in the March evening show "Black Holes" at the William M Thomas Planetarium. Tickets for that show will go on sale on Friday morning, February 21st.
In the weird astronomy category is the announcement last week of an exoplanet with a rotation axis that wobbles wildly in a just a few years time. The orientation of the Earth's rotation axis also wobbles but over a time period of 26,000 years and the range of the tilt angle itself is just a few degrees over an even longer time period of 41,000 years. The weird exoplanet is called Kepler 413-b and its spin axis angle varies by as much as 30 degrees over just 11 years. To top it off Kepler 413-b's orbit around a close pair of orange and red dwarf stars also wobbles up-and-down, so sometimes the orbit will be aligned with our viewpoint on Earth and sometimes it won't. There's probably other planets or a star as yet unseen that is making Kepler 413-b move in such a whacky way.
The attached star chart is centered on the northern sky constellations of Ursa Major with the Big Dipper at one end and Ursa Minor with Polaris, the North Star, at the end of the tail of the little bear. Further east rising up at around 8 PM is Leo the lion with the bright blue-white hot star Regulus at the end of the sickle part and the white hot star Denebola at the lion's tail. The Full Moon was up and to the right of Regulus yesterday night. One day past full, the Moon is now still a bright Waning Gibbous at the mid-way length between Regulus and Denebola. Almost directly overhead at 8:30 PM are the constellations Auriga with bright yellow-white Capella and Gemini with Castor and Pollux at the heads of the twins.
Outshining all of the stars is bright Jupiter in between the twins. It is continuing moving backward in its retrograde motion and will continue to do so until the first week of March. At about 10:45 PM you will be able to see the orange-red Mars rising next to the brilliant white Spica in Virgo. On February 19th a waning gibbous Moon will be slightly right of Spica.
In the early pre-dawn morning look for Venus very low in the southeast. On morning of February 26th a waning crescent Moon will be just left of Venus, a beautiful pairing for you early risers! The following day, February 27th, will hopefully see the successful launch of the first of five Earth-observing missions in 2014, the Global Precipitation Measurement (GPM). GPM is an international satellite mission that will provide a uniform set of observations of the rain and snow all over the globe every three hours. The GPM mission will help advance our understanding of Earth's water and energy cycles, improve the forecasting of extreme events that cause natural disasters, and extend current capabilities of using satellite precipitation information to directly benefit society.
Want to see more of the stars at night and save energy? Shield your lights so that the light only goes down toward the ground. See www.darksky.org for how.
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com