Sirius Astronomer Newsletter

April 2012 Free to members, subscriptions $12 for 12 Volume 39, Number 4 Although the conjunction between Venus and Jupiter has drawn much attention lately, Mars was re- cently at opposition with Earth. OCA member Trey McGriff captured this image of Mars with ice clouds on March 13th. Trey used a Meade 14-inch LX200 to create this image. OCA CLUB MEETING STAR PARTIES COMING UP The free and open club meeting The Black Star Canyon site will be The next session of the Beginners will be held April 13th at 7:30 PM open on April 14th. The Anza site will Class will be held on Friday, April in the Irvine Lecture Hall of the be open on April 21st. Members are 6th at the Heritage Museum of Hashinger Science Center at encouraged to check the website cal- Orange County at 3101 West Har- Chapman University in Orange. endar for the latest updates on star vard Street in Santa Ana. The This month, frequent OCA speaker parties and other events. next two sessions will be on Ap- Dr. Gary Peterson discusses Com- May 4th and . ets: Implications for the Earth. Please check the website calendar for the outreach events this month! Volun- GOTO SIG: TBA NEXT MEETINGS: May 11, June 8 teers are always welcome! Astro-Imagers SIG: Apr. 23, May 15 You are also reminded to check the Remote Telescopes: TBA web site frequently for updates to Astrophysics SIG: Apr. 20, May the calendar of events and other 18 club news. Dark Sky Group: TBA The Planet in the Machine By Diane K. Fisher and Tony Phillips The story goes that a butterfly flapping its wings in Brazil can, over time, cause a tornado in Kansas. The “butterfly effect” is a common term to evoke the com- plexity of interdependent variables affecting weather around the globe. It alludes to the notion that small changes in initial conditions can cause wildly varying outcomes. Now imagine millions of butterflies flapping their wings. And flies and crickets and birds. Now you understand why weather is so complex. All kidding aside, insects are not in control. The real “butterfly effect” is driven by, for example, global winds and ocean currents, polar ice (melting and freezing), clouds and rain, and blowing desert dust. All these things interact with one another in bewilderingly com- plicated ways. And then there’s the human race. If a butterfly can cause a tornado, what can humans cause CloudSat is one of the Earth-observing satellites collecting data that with their boundlessly reckless disturbances of initial will help develop and refine atmospheric circulation models and other conditions? types of weather and climate models. CloudSat’s unique radar system reads the vertical structure of clouds, including liquid water and ice Understanding how it all fits together is a relatively new content, and how clouds affect the distribution of the Sun’s energy in field called Earth system science. Earth system scien- tists work on building and fine-tuning mathematical the atmosphere. See animation of this data simulation at models (computer programs) that describe the complex www.nasa.gov/mission_pages/calipso/multimedia/ inter-relationships of Earth’s carbon, water, energy, and trace gases as they are exchanged between the terrestrial biosphere and the atmosphere. Ultimately, they hope to understand Earth as an integrated system, and model changes in climate over the next 50-100 years. The better the models, the more accurate and detailed will be the image in the crystal ball. NASA’s Earth System Science program provides real-world data for these models via a swarm of Earth-observing satellites. The satellites, which go by names like Terra and Aqua, keep an eye on Earth’s land, biosphere, atmosphere, clouds, ice, and oceans. The data they collect are crucial to the modeling efforts. Some models aim to predict short-term effects—in other words, weather. They may become part of severe weather warning systems and actually save lives. Other models aim to predict long-term effects—or climate. But, long-term predictions are much more difficult and much less likely to be believed by the general population, since only time can actually prove or disprove their validity. After all, small errors become large errors as the model is left to run into the future. However, as the models are further validated with near- and longer-term data, and as different models converge on a common scenario, they become more and more trustworthy to show us the future while we can still do something about it—we hope. For a listing and more information on each of NASA’s (and their partners’) Earth data-gathering missions, visit http:// science.nasa.gov/earth-science/missions/. Kids can get an easy introduction to Earth system science and play Earthy word games at http://spaceplace.nasa.gov/ecosphere . This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aer- onautics and Space Administration. 2 AstroSpace Update April 2012 Gathered by Don Lynn from NASA and other sources Hubble Space Telescope (HST) and various ground-based telescopes are watching a de- layed broadcast of a spectacular outburst from the unstable double-star system Eta Carinae that occurred between 1837 and 1858. Visual observations were written up at the time, but sophisticated science instruments did not exist. But comparison of recent images showed a light echo moving through the clouds surround- ing Eta Carinae. The light echo is just light from the outburst that reflected off clouds, where the light took a path that was about 170 light- years longer than a direct path to us, so we see the echo of the 1837 event now. To prove that it was indeed and echo of that event, the brightness of the echo over the last few years was compared to records of the old visual observations, and the brightness changes matched. Located about 7500 light-years from Earth, Eta Carinae is one of the largest and brightest star systems in our galaxy. During the 1837 event the star shed about 20 solar mass- es and became the 2nd brightest star in our sky. Some of the outflow formed the twin giant lobes seen today. Eta Carinae does not behave like other stars of its class, which is called Lu- minous Blue Variables. They are large, ex- tremely bright stars that are prone to periodic outbursts. But the temperature of Eta’s outflow is much cooler than that of other stars in its class. The blueshift in the spectrum of the light echo shows that the outflow in the 1837 event was moving at about 445,000 mph (700,000 kph), which matched theory. Observations are continuing, as it is expected that a secondary outburst from 1844 should soon appear. HST has also come up with a new class of planet, a waterworld surrounded by a thick, steamy atmosphere. The planet is known as GJ1214b, and was discovered in 2009. Observations soon after showed that it has an atmosphere of water vapor. New HST observations in infrared showed that the whole atmosphere seems to be water vapor, not just a haze layer of water. Since it is a transit- ing planet (passes in front of its star), astronomers have measured its diameter, which is about 2.7 times that of our Earth. It orbits its red-dwarf star every 38 hours at a distance of only 1.3 million miles. This should make its temperature about 450° F (230° C). Its mass has been determined as about 7 times that of Earth, which yields a density of about twice that of water. Earth is 5.5 times as dense as water. That means GJ1214b has much more water and much less rock than Earth. A huge fraction of its mass must be water. The high temperature and pressure should form exotic materials like “hot ice” or “superfluid water”. Theorists expect that GJ1214b formed farther out from its star, where water ice was plentiful, and migrated inward early in the system’s history. In the process, it would have passed through the star’s habitable zone. How long it lingered there is unknown. The planet is in Ophiuchus, and is about 40-light-years from Earth. 3 HST has also found evidence for a cluster of young blue stars encircling one of the 1st intermediate-mass black holes ever discovered. Small black holes (formed from a star collapsing) and supermassive black holes (found at the centers of most large galaxies) are both common. But intermediate-mass black holes are quite rare. This one was found in 2009 toward the edge of galaxy ESO 243-49 by the X-rays given off by material falling into it. Its estimated mass is 20,000 times that of our Sun. New observations by HST show an un- resolved glow about the black hole that matches what should be emitted by a cluster of young blue stars combined with a gaseous disk. It takes both kinds of sources to explain the glow. More observations are needed to confirm these light sources, as other expla- nations are possible. Though young star clusters are common in the disk of a galaxy, they do not appear at the location where this one was found. This suggests that the intermediate-mass black hole came from some other galaxy, probably a dwarf galaxy that was captured by ESO 243-49. The future of the black hole is not known. Depending on its trajectory, which is unknown, it could spiral into the supermassive black hole at the center of ESO 243-49, or it could go into orbit around that galaxy.

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