TAAA Calendar Next Meeting: April 4, 2008

Puffed-Up Atmosphere of a Star-Hugging Gas Giant Planet. This artist's illustration shows an extrasolar planet orbiting very close to its host star. The planet, designated HD 209458b, is about the size of Jupiter. Unlike Jupiter, the planet is so hot that its atmosphere is 'puffed up.' Starlight is heating the planet's atmosphere, causing hot got to escape into space like stream rising from a boiler. HD 209458b completes an orbit every 3.5 days. The Hubble Space Telescope could not image the planet directly because it is too close to the star. Astronomers, including April keynote speaker Dr. Gilda Ballester, used Hubble to analyze the starlight that filtered through the planet's atmosphere. Imprinted on the starlight is information about the atmosphere's structure and chemical makeup. Credits: NASA, ESA and G. Bacon of StScI. Hubblesite-STSCI image.

The next general meeting will be on Friday, April 4, 2008. The public is invited! Please join us for the following informative talks:

Astronomy Essentials Lecture Begins at 6:30 pm

Title: "Objects of the Season" Speaker: Dr. Mary Turner Dr. Turner will give her quarterly update on the best astronomical objects to observe during the spring and early summer seasons.

Speaker: Gilda Ballester, Ph.D. Lunar and Planetary Laboratory General Meeting Talk Begins at 7:30 pm

Title: "Space Telescope Observations of the Atmospheres of Hot-Jupiter Extrasolar Planets" Keynote Speaker: Dr. Gilda Ballester of the Lunar and Planetary Laboratory. Interested in planets around other stars? On April 4, Dr. Gilda Ballester of the Lunar and Planetary Laboratory will speak to the Tucson Amateur Astronomy Association about "Space Telescope Observations of the Atmospheres of Hot-Jupiter Extrasolar Planets." She is the University of Arizona scientist who discovered the "layer-cake" structure of a hot-Jupiter planet, among many other achievements, and is a fascinating and lively speaker. Abstract: The past few years have seen dramatic progress in the characterization of extrasolar planets. Discovery observations are being made, predominantly with the Hubble and Spitzer Space Telescopes, where minute drops in the stellar signal are detected during planetary transits. Dr. Ballester will summarize recent results for two transiting planets, HD 209458b and HD 189733b. The stars these planets orbit are bright enough for high-quality transit observations spanning from the ultraviolet to the infrared wavelengths. These are new kinds of worlds, Jupiter-mass planets in tidally-locked orbits inside 0.05 AU, exposed to extreme environments due to irradiation from their Sun-like stars. (Note: One AU, or Astronomical Unit, is the average distance between the Earth and the Sun. So these large, Jupiter-sized planets orbit very close to their host stars.) The hot upper atmospheres of these gas giant planets are highly inflated and undergo strong atmospheric escape and comet-like interactions as evidenced by detections of H, O and C+ (hydrogen, oxygen, and carbon). The lower atmospheres reach temperatures of 1,000 K, and the resulting composition is exotic, more like small-mass stars than Jupiter-like planets. Water, methane, and hazes of iron or silicates have also been detected. More information: Dr. Ballester's home page: http://vega.lpl.arizona.edu/~gilda Visit: Hubble Probes Layer-Cake Structure of Alien World's Atmosphere. Read about Dr. Ballester's big discovery in February, 2007 of planet HD 209458b in an article by Donna Weaver and Ray Villard of the Space Telescope Science Institute. The signature of hot hydrogen in the atmosphere of the extrasolar planet HD 209458b, by Gilda E. Ballester, David K. Sing, and Floyd Herbert. Technical scientific paper in Nature 445, 511-514 (February 1, 2007) about the "layer-cake" structure of this hot-Jupiter planet. The image at right is from this Nature letter. Caption: The solar-type star, HD 209458, and its 'hot Jupiter" planet in transit are shown in simulated violet light. As in this illustration, the star would appear as a limb-darkened purple disk if seen in near-ultraviolet and violet light. The dense, narrow layer of hot hydrogen atoms discovered by Dr. Ballester and colleagues is represented by the dark absorbing ring around the opaque planetary disk. The bulk of hydrogen atoms in the upper atmosphere, which forms an extensive cloud and also a comet-like tail, is shown in white. The absorbing layer was drawn at twice the altitude and 10 times the thickness to be more easily visible in this illustration, the rest of which has been drawn to scale. (Art credit: Loretta McKibben, UA Lunar and Planetary Lab). Link to the article in Nature's web pages. Distant Planet Mapped for First Time; "Hot Jupiter" Features Fierce Winds, Article by other researchers posted on National Geographic Web News on May 9, 2007. NASA Develops Weather Map of Hot-Jupiter Planet. From May, 2007. Information on hot-Jupiter planets by other researchers.

Also, check out TAAA's web page for Public Star Parties, Lectures, and Events for other astronomy-related happenings.

Upcoming Speakers

Mark your calendars! Following are some exciting upcoming speakers at future TAAA General Meetings:

• Lunar and Planetary Laboratory researcher Dr. Randy Jokipii will speak about the "Solar Heliopause and Voyager" at the June TAAA meeting. The two Voyager spacecraft, which were launched in the 1970's, are now over 90 AUs from the Sun (ninety times the distance from the Earth to the Sun). Have they reached the limit of the Sun's influence on space, the heliopause? These amazing spacecraft are still working and teaching us about the far reaches of the Solar System.
  
  

General Information About Monthly Meetings

Astronomy Essentials talks are very informative for both beginning and advanced amateur astronomers, and provide hands-on information about observing with your telescope. The general meetings have speakers such as professional astronomers or planetary scientists, talking about current astronomical or planetary exploration topics. Meetings usually are held on the first Friday of the month.

If you have questions about the next meeting or joining TAAA, please call (520) 792-6414 or send an email to taaa-info@tucsonastronomy.org.

Other TAAA Meetings In January

Meetings other than the General Meeting and Astronomy Essentials are listed in the table below:

General TAAA Meeting Information

In general, TAAA meetings are held the first Friday of the month at 7:30 PM in the lecture hall (Room N210) at Steward Observatory on the University of Arizona campus. For directions go here. Come early for the Beginner's Lecture (Astronomy Essentials) at 6:30 PM.

The Board of Directors meets once per month, on the second Wednesday at 6:30pm, in Steward Observatory Conference Room N305. Any club member is welcome to attend. If there is a specific item you wish to discuss please contact any board member before the meeting to place the item on the agenda. The building is locked in the evening, look for the remote control doorbell we put out next to the courtyard entrance.

The TAAA generally holds two regularly scheduled star parties per month, one on the dark-of-the-moon weekend at Las Cienegas and one on the weekend before or after the new moon weekend at TIMPA. See the information below on these star parties for dates.

TIMPA and Las Cienegas Star Party Information

Come on out and enjoy the winter skies! TIMPA star parties are great for both beginners and experienced observers. Our novice members can get help with observing issues or equipment problems, as there are many experienced members there who would be happy to help. If you don't own a telescope, come anyway, because there are lots of telescopes set up and everyone is invited to look through them. This is a great way to check out different telescope designs before you make that all important decision to buy. We'll do our best to get you the answers you need. If you have friends or relatives who are curious about amateur astronomy, feel free to bring them along. The TIMPA site features a large parking area, and full restroom facilities. It's also a good idea to bring insect repellent. Directions to the TIMPA site are located on the outside flap of each TAAA newsletter.

Las Cienegas (formerly Empire Ranch) has been TAAA's normal dark-sky observing site for quite a number of years. Please try to arrive before sunset. Stay as long as you like, but let everyone know when you are ready to leave; someone may be taking astro-images. Bring a telescope if you have one, but you don't need one to attend. Any member would be glad to let you look through their telescope. And, there are now restroom facilities at the site. Las Cienegas is at 4000 feet so be prepared for cold temperatures. Attendees should park their vehicles either perpendicular to the airstrip facing toward the center of the strip, or parallel to the airstrip along either side facing west. That way, when you are ready to leave, you will not have to back up and turn on your bright white backup lights. See the directions to Las Cienegas on the outside flap of each TAAA newsletter.

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