Bakersfield Night Sky – January 19, 2013
By Nick Strobel
Bakersfield College is now back in session for the spring semester and classes are full! The previous week was the biannual meeting of the American Astronomical Society ("AAS" for short). The AAS is the major organization of professional astronomers in North America. Its membership also includes other scientists who do research in space-related fields. Every first week of January and June, many astronomy discoveries are announced in the media as the research groups tell their colleagues and the rest of the world what they've found so that other research groups can verify their findings or build on their findings in other ways. There were plenty of astronomy news stories with astrobiology-related ones getting the most interest.
One announced on Wednesday was the possible detection of the molecule hydroxylamine in the gas surrounding a forming star that has been shocked by material flowing out of the star and ramming into the surrounding gas. Hydroxylamine is thought to be an important stepping stone toward the creation of amino acids that are the building blocks of proteins, the workhorse molecules in all forms of life (on Earth at least). The main reason for announcing the possible detection was to get other research groups to verify the finding because it is a fairly weak signal. (Heck, it makes good press too!)
On the exoplanet front, the Kepler team released another batch of planetary candidates. The previous two data releases were in February of 2011 and 2012, so I was surprised (but happy!) that they released their next batch at the AAS meeting. The Kepler space telescope finds exoplanets by looking for tiny drops in the light of stars as planet cross in front of (or "transit") their host star like Venus did for us last June. The latest batch increases the number of planetary candidates by 461 to now over 2700 candidates with over 40% of them in planetary systems with multiple planets and another four candidate planets in the "sweet spot" habitable zone that are less than twice the size of Earth ("super-Earths"). Candidate planets are those that have not been verified yet through follow-up observations to make sure the star dimming is not due to another star as in an eclipsing binary system or a dead star called a white dwarf. Over a hundred planets found by Kepler have been confirmed as of last week, including at least eight that are definitely rocky planets with densities greater than 3 times that of water.
Using the previous Kepler catalog of the over 2300 planet candidates from last February, one group of the Kepler team was able to do some statistical analysis to find that about 70% of the stars have planets in orbits up to the size of the Earth's orbit around the Sun. Being more picky, they find that one-sixth of the stars (17% to be more precise) have planets 0.8 to 1.25 times the size of the Earth in close orbits up to about Mercury's orbit around the Sun. Yes, these would be too hot for liquid water (and life) to survive but they will apply the same statistical techniques when enough small planets in larger orbits have been found. A planet has to have at least three repeated transits of its stars to even be considered a planet candidate and small planets are much harder to detect than bigger planets, especially if the stars are more intrinsically variable than our Sun (as many have been found to be). Therefore, in the first part of the mission, the exoplanet detections have been a bit biased toward the planets with small orbits that have more transits in a given amount of time. As time goes on, the number of planets with larger orbits will build up. The goal of Kepler, though, is to find an Earth-size rocky planet in a Sun-like star's habitable zone. The first candidate to fit the bill was also announced last week. The candidate, named KOI 172.02 for now, orbits its star every 242 days and it is just 1.5 times Earth's size. Making some elementary assumptions and without knowing what the planet's atmosphere and spin speed are like, the global average surface temperature is calculated to be about 46 deg F, just a little colder than the Earth (though the star is "Sun-like", it is slightly cooler than our Sun). One other finding from the statistics is that planets on up to the size of Neptune are not picky about the stars they orbit---they are just as likely to be found around small, cool red dwarf stars as around Sun-like stars.
The Kepler team has decided to release the huge list of 13,000 raw data transit events to the public. This list is the first step in their discovery pipeline toward the creation the planet candidate list. The Kepler teams computer algorithms have become increasingly better at sifting out the good planet candidates from the raw data transit events but their hope is that other research groups will develop even better methods of pruning the list. This is how science should be done---freely sharing data so that others can build on your work and also to make sure you haven't made a mistake. This rarely (never?) happens with corporation-funded research. You can look for planets too using the Kepler data with Zooniverse's Planet Hunters project at planethunters.org. The interface is simple and it doesn't take long to learn how to find those dips in the brightness, so give it a try! This project takes advantage of the excellent pattern-finding abilities of the human brain that is much better than any computer's. It also takes advantage of the abundant interest in exoplanets among the general public and their willingness to help in the research. Curiosity is a gift present in more than just the pros.
For us here at home, the next astronomy event is the close passage of the Waxing Gibbous Moon by Jupiter. The two objects will be about a fingerwidth at arm's length apart from each other on the evening of January 21st. The closest distance on our sky happens at 8 PM Pacific Time. People down in South America will actually see the Moon occult (or cover up) Jupiter. The Moon and Jupiter won't be this close on our sky again for another thirteen years. The attached star chart shows the evening view at 8 PM but brr! will we still be in our cold snap then? By 8 PM tonight and on the 21st, Jupiter will be almost overhead in the southern sky. It is above the head of Taurus. You'll see the bright orange star Aldebaran at the eye of Taurus. Below Taurus will be the brilliant stars of Orion with bright red-orange Betelgeuse at his shoulder, slightly blue Rigel at his knee, and the glittering stars affixed to his belt. The belt stars point downward to the brightest star in the night sky, Sirius at the nose of Canis Major, Orion's hunting dog. To the left of Orion at an altitude mid-way between Orion's belt and Sirius is the bright star Procyon in Orion's little hunting dog, Canis Minor. Above Canis Minor you'll see the two bright stars, Castor and Pollux, at the heads of the Gemini twins. The Moon will be full on the 26th.
Orion will one of the focus constellations for the GLOBE at Night program (the other one is Leo which is high in the sky much later at night) from January 31st to February 9th. GLOBE at night (www.globeatnight.org) invites everybody to measure the amount of light pollution in their area by comparing their view of a bright, famous constellation (such as Orion) with a standard set at different visibility levels. You'll need to know your latititude and longitude: Bakersfield is 35.4 deg N latitude and 119 deg W or use the webapp on the GLOBE at Night website to get your location very precisely. Find Orion no earlier than 8 PM and match your view to one of the GLOBE at Night brightness charts and report your observation on the observation on their website. You can also compare your obseration with thousands of others around the world. 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.
The evening sky will have shifted a bit by mid-February but those constellations and Jupiter will be featured on the dome of the William M Thomas Planetarium for the first show of the spring semester. The schedule for the spring evening shows is now posted on the planetarium's website at www.bakersfieldcollege.edu/planetarium . Tickets go on sale for "Ice Worlds" on January 24th and we hope to have a system in place to purchase tickets online by then. The physical, hardcopy tickets will still need to be picked up at the ticket office but you can at least make the purchase more conveniently. You can always phone in your order as we've had available before. The BC Ticket Office phone number is 395-4326. Tickets will not be available at the door because the show will very likely be sold out by then (if history is any guide). Other shows in the schedule are "Dynamic Earth" in March and the ever-popular "Black Holes" in April.
In the early morning sky very bright Venus is dropping toward the Sun, becoming visible low in the east just half an hour before sunrise tomorrow morning and then just 15 minutes before sunrise by month's end. Saturn is the early morning planet to look for in the east. It becomes visible in the east as a medium-bright star just a little past 1:30 AM halfway between Virgo and Libra. By the time you see Venus, Saturn is still straddled by Virgo and Libra but has shifted with them so it is about halfway up in the southern sky. On the early morning of February 3rd, the Third Quarter Moon will be half a fist at arm's length to the left of Saturn. A chart for that early morning view is posted in the Night Sky section of the planetarium's website.
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
last updated: January 21, 2013
Webpage contact: Nick Strobel