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The WHAC Meeting was held on July 10, 2007 in the CFHT Large Conference Room at the CFHT Headquarters in Waimea.

Doug Summers facilitated the club meeting. He opened the meeting with a welcome to all members both new and old. Those new to WHAC were asked to introduce themselves to the club. There were slightly less than 30 members in attendance, with a half-dozen new faces. We had a few late arrivals who attended a competing astronomy-related event at Keck HQ in Waimea.

Andrew Cooper presented our regular feature The Sky This Month. Andrew showed that there will be a nice grouping of Venus, Saturn, and the Crescent Moon on the evening of July 16. The conjunction will also be nice the evening of July 17. By about August 5 both Venus and Saturn will be lost into the western horizon.

Mercury is well up into the morning sky now. Mercury is at greatest elongation on July 20, and is best seen in the period of July 20-24. By July 30, Mercury will be hard to see as it swiftly dives back into the eastern horizon.

Andrew presented a video clip showing the terrestrial planets in orbit around the Sun. This made is simple to see the reason for the behavior of the planets as described earlier in his presentation.

Andrew shared a video of sunset and moonrise as seen from the Keck Observatory on Mauna Kea. He set up his digital SLR to take one frame per minute, and made a movie out of it. You had to be at the meeting to see and appreciate the video clip. Doug refreshed our collective memory of the star charts that are available on the WHAC website. There was a bit of delay and chaos at the June '07 meeting in trying to get a proper star chart. The WHAC star chart is continually updated and a convenient tool for club members. Doug showed some of the constellations presently visible by using these charts.

Doug then presented a mini-talk on Observing Techniques. Doug began by pointing out that amateur astronomers tend to use one of two techniques to find objects in the night sky. One is the use of a "GoTo" device, such as a telescope with a computer/hand paddle. The user enters the name of the object and the telescope slews to the object. A variant of the GoTo is the "Push To" where a computer device indicates to the user which direction to manually move the telescope to get to a desired object. The second major way to find objects is star hopping. In that technique an observer uses a star chart to hop from star-to-star, ultimately arriving in the vicinity of the object. Then, the observer sweeps about the area to, hopefully, find the object.

Regardless of the technique used, it would be helpful to know whether an object is well placed for viewing. To figure this out, it is necessary to know a few technical tidbits about the night sky.

Everyone is familiar with latitude and longitude lines on the Earth. Each point on the earth has a unique latitude and longitude assigned to it. Similarly, the night sky has a coordinate system. The celestial sphere is the apparent "bowl of stars" overhead in the night sky. Imagine the latitude/longitude lines of the Earth being projected up and onto the celestial sphere. The longitude lines on the celestial sphere are called "Right Ascension" lines and go from 0 hours to 24h59m59s. The "Local Sidereal Time" of an observer is the right ascension of the object that is directly above the observer.
With the above knowledge, it is possible to plan an observing session. For example, Doug showed that he can plan his observing such that he observes objects, in chronological order, as they approach an elevation of 52-degrees. For his telescope, 52-degress is an optimum elevation. Doug has put the Excel observing planning spreadsheet here on the WHAC web site for folks to download and use.

Doug shared that he purchased a Burgess Optical 40mm 2" Paragon eyepiece. He considers it an excellent eyepiece…a "best buy."

Doug called a short break for socializing. We thank CFHT for the cookies and tea!!

The featured talk was by Dr. Josh Walawender, a Post-Doctoral researcher at the Institute for Astronomy at Hilo. His talk was Astrophysics with the Eyeball.

Josh began with an inventory of the Milky Way galaxy. The Milky Way is a spiral, or possibly barred spiral, galaxy. It contains 500B stars, total stellar mass of 200B stars. The Milky Way is 100,000 light years across, and the sun is 25,000 light years away from the nucleus.

So, why are southern skies so good?! Josh presented the following "best of" list -

• Best HII region - Eta Carina Nebula at 7,000 LYA
• Best Open Cluster - Jewel Box at 8,800 LYA
• Best Globular(s) - Omega Centauri and 47 Tuc
• Best Dark Nebula - Coalsack
• Best Satellite Galaxies - SMC, LMC

The southern view is looking out into space through a gap between the Carina-Sagittarius arm and the Perseus arm. This is a relatively unobstructed view. This explains the richness of objects in the south.

Globular clusters were used by astronomers of long ago to determine that the galactic center was towards Sagittarius. You can see this by use of a planetarium software program. Turn off all objects except globulars. Note how they cluster at Sagittarius.

The Milky Way has a mix of low and high mass stars. Low mass stars are low luminosity (i.e., they are intrinsically faint), have lifetimes of "billions" of years, have cooler (red, orange) surfaces, and are common. High mass stars are big, hot, live short lives (15M years for a star 15X mass of the Sun) and are rare. Keep this information about the two classes of stars in mind for a bit.

The arms of the Milky Way, and any galaxy with arms, are due to spiral density waves. These are compression waves that orbit the galaxy. The individual stars orbit in 220MY, while the spiral compression waves are ~60% slower. These compression waves result in the collapse of the interstellar medium wherever the wave (i.e., arm) is. This compression causes formation of stars of all types. However, there is not enough time for the massive blue stars to drift out of the arm. This is why galaxies have arms that appear blue.

You have probably seen the fine edge-on spiral galaxies NGC-4565 and NGC-891. In a pristine dark sky, such as on Mauna Kea, the dust in the Milky Way is easily seen and appears as a dark lane. Some civilizations defined "dark constellations" -- patterns they saw in the dark lanes of the Milky Way. Both the Hawaiians and the Incas mention dark constellations in their mythologies. The Incas had a dark constellation called "The Llama".

These dark clouds consist of dust and gas. A typical cloud is massive (1,000X to 100,000X mass of the sun), cold (10K-50K), and dark. The dark clouds are actually more turbulent than you might think. This results in nucleation of material and formation of stars. The Taurus Molecular Cloud is an example. Astronomers can use millimeter wave telescopes to peer at the star formation in these clouds.

Eventually the new stars pump out enough radiation to ionize the hydrogen. Fine examples of this are the Orion Nebula and the Eagle Nebula. Commonly there is a cluster of hot stars that blows a hole in the glowing cloud. This is called a "Blister HII Region." In the case of the Orion Nebula, the Trapezium cluster is in a hole that has been created by the Trapezium stars. Most of the glow of the Orion Nebula is from the Trapezium "Theta C" star.

The Eta Carina Nebula makes the Orion Nebula look puny by comparison. ECar has ~10 stars comparable to the Theta C star in the Orion Nebula. The Eta Carina star is almost certainly a future supernova. It has over 100 solar masses. In 1843 it underwent a "Great Eruption" where is coughed off about 10 solar masses of material, resulting in a double-lobed structure seen by the Hubble Space Telescope. ECar is ~7,500 LYA, so we are believed to be safe from its future detonation.

In contrast to ECar, low mass stars do not ionize their birthplaces. We get objects like M78 in Orion. The Pleiades and Hyades in Taurus are open clusters. There the cloud has completely dispersed and only the stars remain. The Pleiades are in a bit of dust which they are randomly passing through. This Pleiades Reflection Nebula is not dust that the Pleiades stars formed from. There are many fine open clusters. M37 in Auriga is nice. OB Associations are where the stars have drifted further apart, making their association looser than an open cluster. The Scorpius-Centaurus Association is 400 LYA from the Sun.

Much of the astrophysics of this talk is of objects that you can glimpse with the unaided eye, although a telescope or binoculars can't hurt.

We thank Josh for a truly excellent talk!!

The WHAC Business was short as always. Doug mentioned the "Sizzling Summer Star Party" cookout at the DLNR site this Saturday July 14. We'll cook hot dogs beginning at 5pm, eat by 6pm, and observe by 7pm. It was noted that most of Josh's featured objects are visible in the evening skies.

We took a few moments to recognize Craig Combes in his departure to the mainland. He was presented a small token of appreciation for all he has done. We will miss his camaraderie and thank him profusely for helping found WHAC. We wish him all the best in his move to California.

The next WHAC meeting is Tuesday August 14, 2007 at the Keck Headquarters Hualalai conference room at 7pm. The meeting agenda will feature a talk about the spectacular total lunar eclipse upcoming the night of August 27-28. The full meeting agenda is on the WHAC web site. The traditional pre-meeting dinner is at 6pm at the Parker Ranch Food Court.