April First Light Newsletter

April 2014 Issue 118

AlachuaAstronomyClub.org North Central Florida's Amateur Astronomy Club

April 15, 2014 Total Lunar Eclipse Serving Alachua County since 1987

Member Member M. L. McGaughran obtained this nice image of the Astronomical NASA April 15 total lunar eclipse using a Canon EOS 7D League Night Sky Network and 400 mm lens. The "h Vir" V mag = 5.21 is visible in the upper left of the photograph. (click photograph to enlarge)

Other AAC members who photographed the eclipse include Howard Cohen, Howard Eskildsen, Andy Howell, and Don Loftus.

The Power of the 's Engines

April Space Place article by Dr. Ethan Siegel

Here on Earth, the sun provides us with the vast majority of our energy, striking the top of the atmosphere with up to 1,000 Watts of power per square meter, albeit highly dependent on the sunlight's angle-of-incidence. But remember that the sun is a whopping 150 million kilometers away, and sends an equal amount of radiation in all directions; the Earth-facing direction is nothing special. Even considering sunspots, solar flares, and long-and-short term variations in solar irradiance, the sun's energy output is always constant to about one-part-in-1,000. All told, our parent star consistently outputs an estimated 4 × 1026 Watts of power; one second of the sun's emissions could power all the world's energy needs for over 700,000 .

That's a literally astronomical amount of energy, and it comes about thanks to the hugeness of the sun. With a radius of 700,000 kilometers, it would take 109 Earths, lined up from end-to-end, just to go across the diameter of the sun once. Unlike our Earth, however, the sun is made up of around 70% hydrogen by mass, and it's the individual protons ​- or the nuclei of hydrogen atoms - that fuse together, eventually becoming helium-4 and releasing a tremendous amount of energy. All told, for every four protons that wind up becoming helium-4, a tiny bit of mass - just 0.7% of the original amount - gets converted into energy by E=mc2, and that's where the sun's power originates.

You'd be correct in thinking that fusing ~4 × 1038 protons-per-second gives off a tremendous amount of energy, but remember that nuclear fusion occurs in a huge region of the sun: about the innermost quarter (in radius) is where 99% of it is actively taking place. So there might be 4 × 1026 Watts of power put out, but that's spread out over 2.2 × 1025 cubic meters, meaning the sun's energy output per-unit-volume is just 18 W / m3. Compare this to the average human being, whose basal metabolic rate is equivalent to around 100 Watts, yet takes up just 0.06 cubic meters of space. In other words, you emit 100 times as much energy-per-unit-volume as the sun! It's only because the sun is so large and massive that its power is so great.

It's this slow process, releasing huge amounts of energy per reaction over an incredibly large volume, that has powered life on our world throughout its entire history. It may not appear so impressive if you look at just a tiny region, but - at least for our sun - that huge size really adds up!

Composite of 25 sun images, showing solar activity over a 365 day period.

NASA Solar Dynamics Observatory / Atmospheric Imaging Assembly

S. Wiessinger; post-processing by E. Siegel

Check out these “10 Need-to-Know Things About the Sun”: http://solarsystem.nasa.gov/ planets/profile.cfm?

Kids can learn more about an intriguing solar mystery at NASA's Space Place: http://spaceplace.nasa.gov/sun-corona

Schools Outreach & Star Parties Mike Toomey Ivo Rabell

On April 3rd, the school The March 29th outreach cadre entertained Rosemary Hill over 150 visitors to Williston Observatory star party Elementary School, Levy was cancelled due to County. Chuck Broward, Lisa clouds but keep looking Eager, Alexandrea Matthews, out for future star parties at this Patrick McSween, Ivo Rabell and I site. Until then, here is a history of attended on behalf of the club. Before RHO: sundown, we enjoyed a beautiful crescent moon. Eventually, Jupiter appeared, and Rosemary Hill Observatory is an finally, after patiently waiting out a few astronomical observatory located clouds, we presented many other near Bronson, Florida, 24 miles showcase objects such as the Great Orion southwest of Gainesville, Florida. . The observatory is owned and operated by the University Of Florida. Established in 1967, the observatory sits on 80 acres which were donated by Mrs. Marie Hergert. The observatory was named after the rosemary plant which has grown around the two domes. Rosemary plant is a woody perennial herb with fragrant evergreen needle-like leaves. The name derives from Latin meaning "dew of the sea".

The observatory's two domes are 75 feet above sea level. It also has dormitories for observing runs. The largest dome has a 30 inch Cassegrain reflector telescope built by Tinsley Laboratories and commissioned in 1968. The telescope can be used as an F/4 Newtonian focus or F/16 Cassegrain Paula, Christopher, Frank, and Kylie hold some free focus. The instrument is equipped astronomy reading materials handed out by with a photometric CCD camera, Alexandrea Matthews. filter wheels, and standard Credit: Lisa Statham Posteraro photometric filter. It is occasionally used for instruction, but is primarily used for monitoring active , performing photometry of transiting , and other research purposes. Hopefully next time we will have clear skies!

KidsFest - Upcoming Event

Fun 4 Gators and A Child's Academy are hosting "KidFest" behind Corda Roy's at the corner of 8th Ave & Newberry Road on Saturday, May 3rd.

Visitors will include toddlers, middle Gunnar looks into Mike Toomey's 12½” Newtonian schoolers, and parents. Bring your own kids or grandkids to event. Admission is free! reflecting telescope. Patiently waiting their turn are Jose, Ken, and Taylour. AAC members will bring safe solar telescopes Credit: Lisa Statham Posteraro and show the Sun's prominences, sunspots, and possibly a solar flare. We close out our school at an Alachua County school on May 8th. (click image to enlarge) Please log onto the website and register for the event location. We have one summer program on the calendar so far – Millhopper Library “Fun Friday”. We will be setting up solar viewing – or we will have an indoor alternative if the weather does not cooperate. The program will run on Friday, June 13 from 2 p.m. until about 3 p.m. We anticipate 50 – 100 guests of all ages. Andy Howell and I would like to remind members that attend any of our outreach events to please log their volunteer time on the OurVolts.com web site. This is not a contest among members. Rather, we really would like to demonstrate how much the club contributes to the community. School outreach volunteers will get a reminder after each event to log in. Once you're registered, it takes only For full details of events, please visit seconds to record your time. our Event Calendar.

April & May Meteors Member Profile of the Month Andy Howell Jared Feldman

The Lyrids are active I am a second year from April 16 through 25, Aerospace and peaking on April 21/22. Mechanical The radiant is actually in Engineering student at eastern Hercules, but the University of relatively close to the Florida, hence why I bright star Vega. The shower is moved to Gainesville in late 2012. I associated with Comet Thatcher have a strong interest in all things (C/1861 G1). The best time to see related to space and the universe the Lyrids is anytime after midnight, beyond our own planet. This interest with optimal viewing during the hour led me to my current area of study or so before dawn. Lyra will be and work experience with a Launch directly overhead at this time, Services company. I spent last although a meteor could appear in summer working for United Launch any part of the sky. Alliance where I worked on the Subcontract Management and Bright Lyrid (mag -1) seen early Tuesday Procurement Team. I will be morning, April 22 above Gainesville returning this summer to ULA’s factory in Decatur, Alabama working hands-on assembling their rockets. The main reason I joined the club was to learn more about a telescope given to me by my grandfather while I was cleaning his attic a few months

ago. He was Woody Allen’s chauffeur for over 15 years and he acquired the telescope from Woody. It is a Questar and seems to be in very good shape. I am looking forward to learning more about the telescope In early May, the eta Aquariids and astronomy in general while also swing into view. This shower is getting to know the club's members active from April 19 - May 26, with better! peak activity predicted on May 5/6. This meteor shower is associated with particles from Comet Halley that are on the outbound portions of their orbits around the sun. The radiant rises at 1:30am local time, and best viewing is the hour before dawn when 10-30 meteors per hour might be visible under good conditions.

Meteor observing requires no equipment except your own eyes! It's a great way to get back to basics and enjoy the night sky. Let me know what you see at meteors@alachuaastronomyclub. org. Alachua Astronomy Club Inc

How to Get Started with Observing

Adapted from Astronomical League article by Robert Togni

[Editor's Note: The May 13 public meeting at the Florida Museum features Dr. Mario Motto as our guest speaker. A former president of the American Association of Variable Star Observers, Dr. Motto will talk about variable .]

Variable stars are stars that change brightness. Some important types of variable stars to observe are:

Cepheids - Named after , these luminous stars brighten and fade with clockwork regularity. There are several types of Cepheids ranging from Beta Cepheids with 0.1 magnitude fluctuations and short periods from 3 to 7 hours to W Virginis Stars with fluctuation of about one magnitude over a period of up to 20 days. In 1910, Henrietta Leavitt learned that the longer a Cepheids period was, the brighter the was. This led to Harlow Shapley developing the method of using Cepheids to determine the distance to globular clusters and nearby galaxies.

Mira Stars - These long period variables are very large red pulsating stars having brightness magnitude ranges of up to 11 magnitudes and a time period from 24 days to 5.7 years. These stars can be regular, semiregular, or irregular. Some examples are Mira 2.0 - 9.3 (332 day period), R Leo 5.9 - 10.1 (313 day period), Chi Cygni 3.3 - 14.2 (408 day period), Betelgeuse 0.4 - 1.3 (5.7 year period). Estimates should be done at least twice per month.

Eruptive Stars - This group contains Novae and Nova like stars with a great range of types. Recurrent Nova such as T Coronae Borealis may have outbursts that are decades apart. Stars like U Geminorum and SS Cygni repeat their outbursts every few months. One type, R Coronae Borealis, instead of erupting drops by as much as eight magnitudes. UV Ceti stars may flare several magnitudes in a matter of minutes. This class of stars is not generally recommended for starting observing programs, h. However one of the most exciting stars in the sky is SS Cygni going from ~mag 12 to ~mag 8 in a few days.

Eclipsing Binaries - These are not true variable stars like the ones listed above. They are systems with the stars rotating in the same plane as our line of vision. The best- known example is Algol. Their periods range from 0.2 days to 30 years.

The manuals describe more categories of variable stars and go into greater detail.

How to Estimate a Variable

A good way to start estimating variable stars is to start with Delta Cephei or Algol. On the chart for Delta Cephei note the triangle Delta Cephei, , and . Epsilon Cephei has a magnitude of 4.2 and Zeta has a magnitude of 3.35. Now look at Delta which has a variation of 3.5-4.4. Is it almost as bright as Zeta or dimmer than Epsilon. Is it between the two, closer to the brighter star or closer to the dimmer star. Estimate the brightness to a tenth of a magnitude. You can use binoculars or naked eye.

When you locate the variable field, identify the variable and comparison stars that are closest to the current magnitude of the variable. Be patient. Try to develop map memory, memorizing patterns of the stars. If it doesn't look like the star field in the chart trace out the stars you used to find it and review your maps again. For some stars you may want to sketch your own finder maps from an atlas or atlas program.

Try to get the variable and the chosen comparison star equally distant from the middle. It is nice to have two comparison stars one with a higher and one with a lower magnitude than the variable. Estimate the variable as we discussed with Delta Cephei. Other techniques include throwing the eyepiece out of focus and comparing the brightness. Red stars appear brighter than they really are and this method is often used for comparison. Averted vision may need to be used for dim stars.

Charts for making Observations and setting up a program.

Use these charts for the naked eye binaries and cepheids required: http://www.citizensky.org/ content/10-star-training. Charts for the other variables required in this program can be obtained from AAVSO at http://www.aavso.org/observing/charts/vsp/. For submission to AAVSO, only current charts from the AAVSO Variable Star Plotter (or Citizen Sky) should be used.

The following link shows a list of easy to observe binocular and telescopic stars http://www.aavso.org/easy-stars

Select from these lists stars that are within reach of your equipment, stars that are in season and that can be viewed from your observing site. The AAVSO Bulletin on the AAVSO website can help you determine when Long Period Variables (LPV) are nearing their peak within reach of modest equipment.

To use binoculars on brighter variables or variables as they near maximum choose charts that have North up. These charts are: a, ab, or b. Using a telescope you will probably want c, d, or e charts. These charts have North down just like a reflecting telescope. If you have a Schmidt Cassegrain then left and right will be backwards. Turning the chart around and shining a light through it puts the stars in the right orientation.

Only AAVSO charts will be accepted for submission to AAVSO and for this program.

Recording Observations

Use a log book to record your observations. Your log book gives you a permanent record you can go back to if other data is lost. Each variable observation needs to include the Variable Name (W Cyg) or designation (2132+44), Time, Variable Magnitude, and Comparison Stars. Special conditions are also noted such as moonlight, haze, etc. For your records you will want to record instrument used and possibly magnification.

The time can be in any format - local time or Universal Time - that can be converted later to Julian format, i.e. 8:35 pm CST, 20:35 CST, 2:35 UT.

The variable magnitude should be to a tenth of a magnitude. If the star is too faint for you to see add ( to the magnitude of the dimmest star you can identify i.e. <13.2. Add a question mark or colon if you are not sure of your estimate (i.e. 13.2: or 13.2?).

Visit the AAVSO web site. Take time to look around, you will find a lot of interesting information. Register with AAVSO and you will receive a user name to use when submitting your observations. Submitting your observations will be quick once you get the hang of it. Don't wait till you complete the observing program to submit your observations. Submit them nightly or at the least weekly. As soon as your data is submitted it will be available in a data base that can be observed in charts. You can check the charts and see where your data fell in the data spread.

Glossary

Designation - the six digit number assigned to each variable that approximates it's position in the sky. R Leo's designation is 094211 which represent 9 hours 42 minutes and 11 degrees north. The (last two digits) with an underline or in italics represents south. The designation comes from the 1900 coordinates for the star.

Variable Name - Variable stars in a normally start with the letter R and go through Z and are named in the order of discovery. After Z, it goes RR, RS, RT, .... SS, ST, SU ... ZZ. Then back to AA ... AZ, BB ... BZ ... QZ with J left out. When a constellation exceeds these 334 letters the next variable star becomes V335 and so on. Naked eye variable stars normally have regular constellation nomenclature or names because they were placed on early charts, like Omicron Ceti ("Mira").

Julian Day - The Julian day is the number of the day from January 1, 4713 BC at 12:00 noon. May 1, 1997 at 12 noon is 2,450,570.00 days since Jan 1, 4713 BC. May 1, 1997 at 12 midnight is 2,450,570.50. If you use the AAVSO on line data entry, you can enter Universal Time or the Julian Date (which is preferred). AAVSO provides a Julian Date calendar each year.

References

Astronomical League Variable Star Program Variable Star Observing Introduction

American Association of Variable Stars Visual Observing Manual

Robert Burnham, Jr.; Burnham's Celestial Handbooks ;Dover Publications, Inc. David H. Levy; The Sky, a user's guide , Cambridge University Press

David H. Levy; Observing Variable Stars , a guide for the beginner ; Cambridge University Press

Webb Society Deep-Sky Observer's Handbook, Volume 8, Variable Stars; Enslow Publishers, Inc.

Richard Dibon-Smith; Starlist 2000; John Wiley and Sons

Leslie C. Peltier; Starlight Nights: The Adventures of a Star-Gazer; Harper and Row 1965

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Contact email: [email protected] Alachua Astronomy Club, Inc. P.O. Box 141591 Gainesville, FL 32614-1591

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