Issue 118 - Apr 2014

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
M. L. McGaughran obtained this nice image of the Astronomical
League
April 15 total lunar eclipse using a Canon EOS 7D
Member
NASA
Night Sky Network
and 400 mm lens. The star "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 Sun'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 years.
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
Mike Toomey
Outreach & Star Parties
Ivo Rabell
On April 3rd, the school
outreach cadre entertained
over 150 visitors to Williston
Elementary School, Levy
County. Chuck Broward, Lisa
Eager, Alexandrea Matthews,
Patrick McSween, Ivo Rabell and I
attended on behalf of the club. Before
sundown, we enjoyed a beautiful crescent
moon. Eventually, Jupiter appeared, and
finally, after patiently waiting out a few
clouds, we presented many other
showcase objects such as the Great Orion
Nebula.
The
March
29th
Rosemary
Hill
Observatory star party
was cancelled due to
clouds but keep looking
out for future star parties at this
site. Until then, here is a history of
RHO:
Rosemary Hill Observatory is an
astronomical observatory located
near Bronson, Florida, 24 miles
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".
Paula, Christopher, Frank, and Kylie hold some free
astronomy reading materials handed out by
Alexandrea Matthews.
Credit: Lisa Statham Posteraro
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
focus. The instrument is equipped
with a photometric CCD camera,
filter
wheels,
and
standard
photometric filter. It is occasionally
used for instruction, but is primarily
used for monitoring active galaxies,
performing photometry of transiting
exoplanets, 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.
Gunnar looks into Mike Toomey's 12½” Newtonian
reflecting telescope. Patiently waiting their turn are
Jose, Ken, and Taylour.
Credit: Lisa Statham Posteraro
We close out our school year at an
Alachua County school on May 8th.
Please log onto the website and register
for the event location.
Visitors will include toddlers, middle
schoolers, and parents. Bring your own kids
or grandkids to event. Admission is free!
AAC members will bring safe solar telescopes
and show the Sun's prominences, sunspots,
and possibly a solar flare.
(click image to enlarge)
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
seconds to record your time.
For full details of events, please visit
our Event Calendar.
April & May Meteors
Andy Howell
Member Profile of the Month
Jared Feldman
The Lyrids are active
from April 16 through 25,
peaking on April 21/22.
The radiant is actually in
eastern Hercules, but
relatively close to the
bright star Vega. The shower is
associated with Comet Thatcher
(C/1861 G1). The best time to see
the Lyrids is anytime after midnight,
with optimal viewing during the hour
or so before dawn. Lyra will be
directly overhead at this time,
although a meteor could appear in
any part of the sky.
Bright Lyrid (mag -1) seen early Tuesday
morning, April 22 above Gainesville
In early May, the eta Aquariids
swing into view. This shower is
active from April 19 - May 26, with
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.
I am a second year
Aerospace
and
Mechanical
Engineering student at
the
University
of
Florida, hence why I
moved to Gainesville in late 2012. I
have a strong interest in all things
related to space and the universe
beyond our own planet. This interest
led me to my current area of study
and work experience with a Launch
Services company. I spent last
summer working for United Launch
Alliance where I worked on the
Subcontract
Management
and
Procurement Team. I will be
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
and astronomy in general while also
getting to know the club's members
better!
Alachua Astronomy
Club Inc
How to Get Started with Variable Star 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 stars.]
Variable stars are stars that change brightness. Some important types of variable stars to
observe are:
Cepheids - Named after Delta Cephei, 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 absolute magnitude 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
binary star systems with the stars rotating in the same plane as our line of vision. The bestknown 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, Epsilon Cephei, and Zeta Cephei. 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 declination (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 constellation 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
Copyright © 2014 Alachua Astronomy Club, Inc. All rights reserved.
Contact email: [email protected]
Alachua Astronomy Club, Inc.
P.O. Box 141591
Gainesville, FL 32614-1591
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