From the Director

Rex

 

 

 

by Rex Parker, Director

NEAF Impressionism. Energized from attending the Northeast Astronomy Forum (NEAF), I returned to Princeton contemplating our roles on the stage of science, exploration, and community. The “World’s Largest Astronomy & Space Expo” was conceived and produced for the past 20 years by members of the Rockland (NY) Astronomy Club. It has grown remarkably with 120 exhibitors participating this year. Advances in technology, telescope instrumentation, and knowledge were evident in every direction. Talks on stage at the “Celestron Theatre” were inspiring and wide-ranging. Young speakers confirmed the importance of mentoring by local astronomy clubs and spoke glowingly of that first (and second!) telescope and their growing interest in science and math as they head to college. 2006 Nobel physics laureate John Mather gave an exciting preview of the James Webb Space Telescope, future successor to Hubble, where he is a senior project scientist.

On display throughout NEAF were telescopes large and small, precision equatorial and portable alt-az type mounts, camera systems using the latest CCD and CMOS sensors, cool gadgets, devices, inventions, innovative software and techniques for displaying astro images. The AAAP was an active participant in acquiring some of this new technology in the form of new high sensitivity astro cameras soon to be ready for member use at the Observatory. NEAF was all about depicting the visual impression of the moment, especially in terms of the shifting effect of light and color – the very definition of impressionism!


Jupiter the Star of Show on Member Night at Observatory, Sat. May 12 (rain date May 19). The new moon is May 15, so this get-together for members and family/friends will be a good opportunity to see the deep sky as well as planets. Sunset will be at 8:09 pm and Jupiter rises in the SE by mid-evening May 15. It will be one of the best weeks of the year to observe Jupiter, which reaches its closest point to earth (opposition) the week before. Below is a photo of Jupiter taken in Sept 2010, showing movement of the Great Red Spot in two images taken less than 1 hour apart tin time. In May 2018 Jupiter will be very bright reaching magnitude -2.5, and large approaching 45 arc-sec diameter (this is huge by planetary observing standards!). Come out and learn more about observing and telescope equipment, get to know others in the club, and see if you can detect the Great Red Spot on May 12.

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From the Program Chair

By Ira Polans

James Lowenthal

James Lowenthal

The May meeting will be held on the 8th at 7:30PM in the auditorium (Room 145) of Peyton Hall on the Princeton University campus.

Featured Speaker: The featured speaker is Dr. James Lowenthal of Smith College. His talk is on “Stalking the most luminous galaxies in the Universe with Hubble and the Large Millimeter Telescope”.

Most stars that formed in the first half of the Universe’s lifetime were made in massive, dusty starburst galaxies that are largely hidden from view but shine brightly in far-infrared wavelengths. The FIR light from those galaxies is red-shifted by the Universe’s expansion into the sub-millimeter. We used the Planck satellite to select the most luminous sub-millimeter galaxies at high red-shift and refined the list and confirmed them with a battery of other telescopes including the Herschel satellite, the Very Large Array, the WISE satellite, and the 50-m Large Millimeter Telescope. None of those provided a sharp view of the distant dusty starbursts. New images from Hubble Space Telescope, however, have unveiled a spectacular view: nearly all the brightest SMGs at high red-shift are strongly gravitationally lensed by massive intervening galaxies and groups or clusters of galaxies: most show simple or complex Einstein rings, while others show giant arcs implying lensing masses M>10^14 solar masses. These new images, supplemented with follow-up data from the 8-m Gemini South telescope and ALMA, provide a path to study the most extreme star-forming galaxies known at spatial scales of 100pc or even less, letting us address a fundamental question: what process fuels the extraordinary activity of SMGs?

Member Talk: This month’s 10 minute talk is by Bill Murray on Stellafane. If you don’t know about this event, you will after Bill’s talk!

We are looking for members to give a talk for next year. Maybe you’re doing something astronomically interesting during the summer break? Perhaps you want to share why astronomy is so fascinating to you? If you are interested in giving a talk please contact program@princetonastronomy.org.

Pre-Meeting Dinner: Prior to the meeting there will be a meet-the-speaker dinner at 6PM at Winberie’s in Palmer Square. If you’re interested in attending please contact no later than Noon on May 8.

We look forward to seeing you at dinner and the meeting!

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Naming Uranus

by David Lechter

While looking through a cornucopia of astronomical images at the Pinterest web site I came across the following image that is actually page 49 of an old book entitled “Smith’s Illustrated Astronomy”(3).

I was able to download a digital copy of the book from (1) and the following quote from the Preface helps explain the purpose of Smith’s book:

“It has been the object of the author of this Illustrated Astronomy, to present all the distinguishing principles in physical Astronomy with as few words as possible; but with such occular demonstrations, by way of diagrams and maps, as shall make the subject easily understood. The letter press descriptions and the illustrations will invariably be found at the same opening of the book; and more explanatory cuts are given, and at a much less price than have been given in any other elementary Astronomy.

This work is designed for common schools, but may be used with advantage as an introductory work in high-schools and academies. In the preparation of these pages most of the best works in our language have been consulted, and the best standard authorities, with regard to new discoveries and facts, have governed the author’s decisions”.

The image follows:

Orbits of the Planets

Orbits of the Planets

What struck my eye is that the image shows not only the known planets and some asteroids but their orbital inclinations with respect to the ecliptic. You’ll agree that it is very difficult to read the planets’ names and inclinations recorded in the image; some are relatively clear but some are not. Noteworthy, and difficult to see, is the planet labeled as Herschel, the discoverer of Uranus. William Herschel discovered Uranus in March 13, 1781.

Despite the difficulty in reading the orbital inclinations, a check with Wikipedia(2) shows the image is correct in Smith’s illustration of the planets’ orbital inclinations as seen in Table 1.

Table 1. Inclinations of the Planets (as seen in the image)

Planet Inclination
Venus 3.39
Mars 1.85
Hershel 0.77
Earth 0
Jupiter 1.31
Saturn 2.49
Mercury 7.0

Neptune is notably absent in the image. Neptune was observed with a telescope on September 23, 1846 by Johann Gottfried Galle, a director of the Berlin Observatory just three years before the first edition of Smith’s textbook. One can only imagine why Neptune is left out of the image. In fairness to Smith, he does discuss Herschel (Uranus) and Leverrier (Neptune) on page 30. Maybe the image got too crowded or maybe it was an oversight on the artist’s part. We’ll never know I suppose.

We can get a taste of the debate over what to name Herschel’s newly-discovered planet by reading a letter written by Caroline Herschel, William’s sister, to Maria Mitchell and quoted by Dava Sobel in her book on the planets(4). Maria Mitchell, incidentally was an American Astronomer and discoverer of “Miss Mitchell’s Comet”! Caroline’s letter describes how William wanted to name the planet “Georgium Sidus” acknowledging the King’s kindness, while some people in France campaigned for “Planet Herschel”. Sobel mentions that “many other names came forward” too. Herr Bode, director of the Berlin Observatory suggested “Uranus” who “sought safety in mythology”. Sobel notes that sixty years were to pass before the name Uranus was generally accepted. (Incidentally, during this time a German chemist, Martin Heinrich Klaproth, extracted a metal from pitchblende and called it Uranium).

Perhaps we now know why Smith used the name Herschel instead of Uranus in his diagram seen above.

History shows us that continuing studies of ‘Uranus’ a planet with a perturbed orbit led to the discovery of Neptune, a planet that may have been observed by Galileo(5), but was discovered mostly through mathematics!

Sources:

  1. Smith’s illustration

  2. Orbital inclination

  3. Smith, Asa. Smith’s Illustrated Astronomy. New York: Daniel Burgess & Co. 1855.

  4. Sobel, Dava. The Planets. New York: Penguin Books, 2005.

  5. Neptune
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Daystar

by John Church

Fear no more the heat o’ the sun,

Nor the furious winter’s rages.

– Cymbeline, Act IV

Whenever I have trouble getting to sleep, which sometimes happens to people as they get older, I just think about the sun.

I first learned interesting things about the sun from “The Beginner’s Star-Book,” a delightful and classic introduction to astronomy by Kelvin McKready. My father brought it home from the Virginia State Library when I was about ten. I devoured every page, although many of the technical details were way over my head. This book was largely responsible for my lifelong interest in astronomy, some bits of which I have written about elsewhere. When I left Richmond after finishing college, the book stayed in my parents’ home, having been discarded by the library. My father gave it to me, and I have it still.

McKready’s excellent exposition was interspersed with astronomy-related poetical selections from Victorians such as Matthew Arnold and Alfred Tennyson. A sample of the latter will suffice:

My mood is changed, for it fell at a time of year

When the face of the night is fair on the dewy downs,

And the shining daffodil dies, and the Charioteer

And starry Gemini hand like glorious crowns

O’er Orion’s grave low down in the west …

A ten-year-old boy cared little for the maudlin sentimentality of Maud (he might, later on), but he was greatly impressed by such imagery. For he himself had seen Auriga and the Heavenly Twins keeping vigil above the place where the Giant Hunter rested of a delicious late April Richmond evening. And he had shared the thrill of chill November twilights such as those watched by the narrator of Locksley Hall:

Many a night I saw the Pleiads, rising thro’ the mellow shade,

Glitter like a swarm of fireflies tangled in a silver braid.

There was a chapter in McKready’s book describing the sun. Now the sun is something we all take for granted: rising early in the morning to send us off to school or work, then setting in the evening as we reflect on the day and prepare for dinner. It can get in our eyes during our morning or evening commutes in wintertime, might burn us in the summer, and doesn’t always shine when we most want it to. Reading McKready, however, gives us a little more respect for this monstrous thing that heats the earth and keeps it in its orbit.

Anthropocentric conceit would have us imagine that the sun exists for our benefit alone, but some elementary facts disabuse us of this notion. As seen from the sun, the earth is nothing but a ridiculously tiny speck, no bigger than a gnat would appear from several yards away. The earth catches only one part in two billion, two hundred million of the total energy that the sun pours out into space. Put another way, the sun could light up and power well over two billion earths at once. Imagine the amount of energy that the total daylit side of earth is receiving at any one instant, multiply it by this factor, and you will have some remote idea of the sun’s power. And it has been doing this for billions of years and will continue to do so for billions more. (Peace, Carl Sagan, I didn’t mean to overuse your proprietary word.)

Well over a million earths could fit inside the sun’s globe. If the earth were at its center, the moon in its orbit would be only a little more than halfway out to the sun’s surface. What an enormous thing.

Scientists sometimes entertain themselves by doing approximate calculations in their heads. (Yes, aren’t we such jolly people?) Lying in bed once, I was curious as to about how much of the sun’s surface would be required to take care of the entire earth’s solar energy budget. As we learned in elementary geometry, the surface area of a sphere is four times pi times the square of the sphere’s radius. Astronomy buffs know, or ought to know, that the sun’s radius is 432,000 miles, or 4.32 times 10 to the 5th power (expressed this way for ease in handling such large numbers). Square this in your head and you will have roughly 20 times 10 to the 10th power. And four times pi is about 12. So the area of the sun’s surface must be about 240 times 10 to the 10th power square miles; simplify this to 2.4 times 10 to the 12th power. In other words, 2.4 trillion square miles.

Now we already know that the sun can light up 2.2 billion earths, as McKready told us. Therefore, it would take only about eleven hundred square miles of the sun’s surface to give full daylight and heat to the entire sunlit side of the earth. Now eleven hundred square miles is not really very much; it’s about the size of two average counties in the small state of New Jersey where I live. So the sun must be incredibly hot and bright. Well, any fool knew that without doing the calculation, but it did help put me to sleep.

Deep inside the sun, five million tons of matter are being tortured to death every second in nuclear reactions and converted to energy by the enormous gravitational pressure of the overlying material. The sun would really like to explode from all this released energy, but it can’t because of this same gravitational confinement, and everything stays almost perfectly in balance. As it slowly loses mass – the rate is about one earth equivalent per 40 million years – it continually expands at a very slow rate, partly because of decreased gravity, but mostly because its power output gradually increases due to complicated changes in its mode of energy generation. After many billions of years it will become a “red giant,” swelling to about the size of the earth’s orbit and melting it completely. Long before things get to this stage, we shall have had to move; it’s not too early to begin thinking about it.

Now for some more illuminating facts. I couldn’t figure these out in my head the other night because I was already bored to death and sound asleep (see, this technique works). The total power being continually released by the sun is about 5 times 10 to the 23rd power horsepower. A number of this size is especially interesting to chemists, because it’s close to what’s known as “Avogadro’s number.” This latter number, about 6 times 10 to the 23rd power, is the number of molecules in what’s called a “gram-molecule” (also known as a “mole”) of any chemical compound.

Take water as an example, made of two hydrogen atoms and one oxygen as we already know. Hydrogen has an atomic weight of very close to 1 (convenient, since it’s the lightest element), and oxygen is 16. So the molecular weight of water is 18 (18.02 if you want to get technical). Now a mole of any compound is defined as the number of grams of that compound numerically equal to its molecular weight. So a mole of water has a mass of 18.02 grams. Volumewise, this is between three and four teaspoonfuls of water. This small swallow has more molecules in it than the horsepower of the sun! Hard to believe, but true.

One more factoid for insomniacs and I’m done. How much of the sun’s surface do I personally need to keep me alive? An average person’s metabolic power consumption is about a hundred watts, or like one bright conventional light bulb. This is the power output of a little under two square millimeters of the sun’s surface. If you do the math, to power all the seven billion people on earth would theoretically require a piece of the sun only about the size of the playing surface at a baseball stadium.

Play ball! But please put on some sunscreen.

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Communiversity Day 2018

by Larry Kane, John Miller

We had a great turnout by AAAP members and we had an opportunity to speak with, and provide literature to, a lot of attendees. When I had the time, I took a few pictures, shown below. This event continues to be a major recruiting effort for the AAAP and should be a part of our our outreach efforts in the future.

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Wiggly Jiggilies

by Ted Frimet

or when black holes collide

Commercial break. All had a great time, during our AAAP outreach. Three telescopes were present, one manned by Dr David Letcher, the other by Outreach Chair, Gene Allen. The third telescope, my 8” SCT push-to, used for hands on – in my own humble opinion, was the star of the show. As you all know, most of our equipment is very expensive. So it goes. An observer must retain domain over his or her telescope and mount. However, this eight inch lady of the light is forever in the public domain. You should see kids faces light up. Even parents. Yes, even with Venus as the only “star” of the show due to light pollution and a sliver of the moon. The experience is especially rewarding. I can’t say enough good things about the Amateur Astronomers Association of Princeton for sponsoring Outreach. Welcome back, audience.

How best to solve a maze? I’ve always been fond of working backwards. For the most part, maze designers made them difficult. They are, or were, a source of entertainment, if not simply down right time consuming. Most persons solving a maze, take the time of an eyepiece view to solve. As astronomers, we take in the scenery, sweeping from West to East. And lastly drop in on the latent glowing red of a binary system at a higher magnification. Was I alluding that a maze is like the night sky? Maybe so. If you like mazes, then I challenge you to backtrack from the end to the beginning of this passage!

Determined as you may be to solve to the bards room, from entry to exit, and not vice-versa, my maze may be somewhat challenging. I intend to tease and defeat those that are back-door solvers. And you few that dip the ink into an old fashioned labyrinth, now manage to make my mental glee that much harder to obtain. However, the vocabulary to describe said “maze-management” remains a constant. Or at least a scant web search suggests that to be so.

Welcome to my reverse maze. As of the time of this writing, the Lyrids are not at full peak. And I will be a tired soul for staying the course, late into the evening to view them. And at first light, I will engage the star drive to Sunday’s North East Astronomy Forum (NEAF 2018 – Yes, Saturday was a sleep-in). Yes. Definitely tired. Maybe skip the Lyrids, and go to bed early?

Friday was a Minatour. I found him imprisoned in the labyrinth of Knossos. It was the Annual Meeting of the International Occultation Timing Association (IOTA) of North America. And lest I am questioned to answer for myself, you will find me as the center focus of King Minos of Crete. You’ve got to admit, though. Minatour is such a cool sounding maze based name. Truly, the IOTA meeting was more of maze junction, or a decision point. It was a place where we have to decide between at least two alternative paths. Keep alert! Be certain that all discussions held, here, at the Crowne Plaza in Suffern, NY were all revelations. And many silent decisions were being made by the nube in the back row. And it is here, in brief that I present the alternative path I have discovered. You knew it already. I simply did not say so, up front.

Regulus before the occultation.

Regulus before the occultation. Courtesy David Dunham

White Dwarf during the occultation.

White Dwarf during the occultation. Courtesy David Dunham

Regulus is such a bright star. He is why we use him as a guide, during the spring night. With the help of fellow Amateur Astronomer John Miller, my sighting of Leo’s alpha is now correct. A knowledge of one more star locus meets my monthly quota. And then came IOTA. I learned from two still pictures that an occultation event dims even the mighty Regulus. And in doing so, revealed the secret of his binary accomplice; a White Dwarf. I am still uncertain as to how a high UV emitter was revealed by white starlight. Still – the evidence lay before me in the images portrayed on the projection screen, during an IOTA talk. The Regulus occultation by the asteroid 268 Adorea appears above. Let us forgo the aforementioned question on account of my humble learning process. We now delve into the more mysterious nature of the occult.

We can discover binary star systems while being visual observers. The fainter, gravitationally bound doublet was previously obscured by the Regulus’ absolute magnitude [-0.57]. The dwarf remained cloaked until a passing asteroid blinked her twin into a temporary visual oblivion. Our three actors; the guide star, a dwarf, and asteroid formed the maze vortex. Ultimately they were linked together, if only for a brief instant in time, and in space. And then the asteroid continued on thru her passageway, bound to repeat her spiral retreat to the outerwall. And once again, orbit back thru the maze.

There is no rest for the weary. However, do take a breath, and have a snack. I’m getting up to get a cup of coffee… Fear not, ye star traveler. I promise not to lead you into the cul-de-sac of Troy. I will not lay before you the blind alley of the maze.

This month might have been, for me, a classical bottleneck. Outreach to scouts, we were told, were for fourth graders in attendance. How difficult could it be? Plan on a chance encounter on my ruse in “how to ride a light beam”, in this months Sidereal Times. There you will find the result of an ask for an academic paper. Never an easy task. And then to convey the essence of the essay message into a hands on experiment? Maybe a little more difficult? I dare say.

After the fact, but before the outreach encounter, I looked up some data on our scouts. Those in attendance were not your everyday fourth graders. These were STEM participants. And I will tell you, frankly, how their behavior was outmatched only by their scientific prowess. They were knowledgeable, and formed solid, lucid questions. Clearly, even as I strike the keys, I show my mazes end. I let you all know that these STEM scouts are a replacement for me. In so very short years, they too will search and find AAAP and the wonders of Sidereal Times!

The paper was a mazes’ bottleneck, and so it was not presented at outreach. It did become the backbone for replying to the Scout Master, as well as document in hand for Ms. Gold. She was the main point of contact, at the Scouts outing. Ms. Gold is the noteworthy STEM teacher for these participants. Reading my information paper was clearly off the menu. Ms. Gold made sure that the essay would be in the hands of those few that were up to the task, including Mr. T – a parent that was acutely aware of the many color palettes of Hubble Space Telescope astrophotography.

There was a diverse range of cosmological knowledge spread upon the 15 astronomers in our STEM group. A later night topic, staved off until the last possible minutes, was on Cherenkov radiation. Followed by a discussion of white dwarf UV emissions and the nebula that re-radiate their light. In demonstration, we shone a small UV flashlight onto some uranium glass; while we all went a-gaze with wonder at the glowing yellow-green light of re-radiation under then, darker skies.

Push back the clock, even earlier. All were in attendance. Due to an abundance of artificial light in the parking lot, more con-fab was called for. And then we showed, with two outstretched arms a demonstration of two black holes in a death spiral. My impression was wanting. All remained well mannered. And then came the question, “what sound does 63 solar mass’ of black holes make when they collide” ? Fortunately for us, AAAP was graced with the LIGO talk of Princeton University Professor Frans Pretorius. And I had the good luck to have heard a reinforced lecture by Kip Thorne, a few days later. Now, how to transcend the lecture room to the parking lot? Simple. Wait on the kids to answer. And answer, they did! “Boom, arrrgh, howl”, loud noises!! Maybe even a bang and crash!! And then I lamely said, “chirp”.

They looked at me, like I as out of my mind. Ok, they got me. Even if they don’t read my essays, they know I’m unusual. Since I listened to Drs. Thorne and Pretorius, I became Daedalus, anew. Yet here as craftsman, a skilled artisan, I had to manage a conveyance of a song bird. With the words of two Phd’s (Pretorius and Thorne) in my mouth; I uttered again, “chirp”. Yes. I explained that as the scientists used the interferometer to monitor one dimension of a gravity wave – our first – they decided to funnel it into a speaker. And our STEM kids were wide eyed with wonder. Although I must admit, in a less than passing fashion, that some body language expressed contempt for a bird call from a black hole. Really? Could you blame them? Chirp? Yup. Thanks, Kip. Diddo to you, Frans.

Earlier, Ms. Gold had described that they had created a model of our solar system. And pointed out how they learned how massive Jupiter was and how tiny the inner planets were by comparison. More than one scout mentioned this to me, in passing. Where was this Ven I searched for? Where is the knowledge point, a nexus where we can transcend the solar system of old, and introduce the galaxy of new? And what of the Universe of greater ascent? Asking for a volunteer; one STEM participant became the “galaxy center point”, while others formed up the many arms of our spiral galaxy. And around and around they walked – dancing the dance of the ever whirling galactic outreach. They were impressive. I am so proud of them. They produced a great spiral, that evening!

Fortunately outreach does not have to come at a high price; nor does it need to be overly complex. With six tea lights in hand – LED lights – a version for 50 cents a pop – a volunteer was selected to choose a remaining five. And six scouts sought to line up the lights, at a distance. Some close. Some from afar. And all within the safety of oversight of parents, and leadership.

Having first observed all lights at the same distance; and same brightness; they learned absolute magnitude. And now given the opportunity to see their lights close and far – they learned apparent magnitude. Here’s the tricky part. Asking our STEM participants the hard question. If two stars appear to have the same brightness, and yet are hundreds of light years apart, how do you account for this? And to my excitement, my new peer group, a group of 15 exceptional minds, gave me the answer. Among them was a spokesperson who sang out! I was so proud. So very happy not to have answered myself. If you want the whole tale of two magnitudes, please read, “how to ride a light beam”, also found in this months Sidereal Times.

If Aristotle were here, he would be analyzing this tome, a Poetics of sorts. I was going to stop. But I could not help myself. The kids were introduced to Minkowski space of length, width, height and time. And when confronted with passing thru the event horizon of a black hole – having time swap out for a dimension and having that dimension of time flowing in against them – they intuitively agreed that this flow into the black hole would never let anything escape against this arrow of time. Yes. Truly our STEM kids will need the shield of Achilles to accompany the sword of Aegeus in our maze. My essays’ are insufficient. Perhaps the AAAP outreach was never needed. There is a complication in the continuum. Due to a non-anticipated fold in space-time, it appears that all fifteen students were already in attendance at Princeton University. In which case, I was never here. And neither are you. Where is that second cup of coffee? A brief reference to Douglas Adams reveals that the cup appeared in the many worlds version of where lost pens go to. Say “hello” to Douglas, for me, when you see ‘em. Tell him I want my coffee mug back. It was my favorite.

Ah yes. The beginning of the maze presents itself. Now, stand up – raise up your arms and wiggly jigglie all that extra energy! I, as Theseus, lead the way back to the beginning. However, if you took the challenge of paragraph two, you’ve started here. Whoops. Endless loop. Or was it particulate matter, in the forms of electrons, traveling faster than light in an optical density greater than one ? Blue light, or sound waves compressed into a sonic boom? Take your pick. There lay your Minotaur in sight and in sound.

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The new exoplanet hunter

by Prasad Ganti

The Falcon 9 rocket blasted off into space like what has now become a routine launch. This time the payload was a space telescope on a mission, a more powerful set of eyes, peeping into the heavens for worlds beyond our own, to prove that we and our home planet are not all that unique in the Universe.

It is only in the last decade or so that we have been identifying planets orbiting other stars. Having overcome some of the technical challenges to detect something which is not easily visible, Which does not have light of its own, unlike the stars, whose reflection of the starlight is way too feeble. Which causes a very slight dimming of light when it comes in front of its parent star. Which causes its parent star to wobble very slightly as it goes around and around.

The current space telescope Kepler, was a pathfinder in terms of identifying about four thousand such exoplanets. While most of them were far and bigger than our own Earth. Being the first generation of such a finder, the telescope had its own limitations. It looked at only a small patch of the sky. And at stars thousands of light years away.

The new satellite called TESS (Transit Exoplanet Survey Satellite) will continue the legacy. It will be more focused in terms of detecting smaller planets (between the sizes of our own Earth and that of Neptune) and which are closer to us. Closeness is a relative term in astronomy. TESS will focus on a few tens or hundreds of light years, which is still far enough for a human visit. Smaller planets are likely to be rocky and at appropriate distance from the stars called the goldilocks zone, likely to host life. Also, relative proximity to our solar system can make the candidates amenable for more detailed study using other telescopes, both ground and space based.

While Kepler is on its last legs, having been a trailblazer, technology has advanced on our planet. TESS gains from such advances. Powerful cameras – four 16.8-megapixel cameras, each camera having seven lenses, which funnel light from the heavens toward four CCD (Charge Coupled Devices) image sensors which have been custom built by MIT’s (Massachusetts Institute of Technology) Lincoln labs. A single camera can cover a patch of sky 24 degrees wide by 24 degrees high. TESS’s main mission is to sweep almost the entire sky and focus on nearby stars. The search will be for about 200,000 relatively bright, pre-selected stars. The candidate red-dwarf stars are not big. They are not too bright, but because of shorter distances, appear brighter. Such stars live longer, burning their fuel at a slower rate. The longer life gives a greater chance for life to evolve on its planets.

Now a word about the orbit of this space telescope. It is an highly elliptical orbit. An ellipse is a stretched out circle. The stretching is pretty significant in this case. It will travel out as far as the moon is away from Earth, and then come back very close to the Earth every fourteen days. Most of the time spent away from the Earth, will protect it from the Earth’s Van Allen radiation belts. After all, space is a very hostile environment. Both to life as well as to spacecraft.

When TESS comes very close to the Earth, it will beam down data at a higher bandwidth. We understand the power of high bandwidth mobile networks like 4G or 5G when it comes to showing us videos on our phones. And TESS will collect huge amounts of data which needs to be analyzed for exoplanet detection. This highly elongated orbit is the first for any spacecraft. It will keep TESS very stable for longer time with minimal fuel consumption. Using a combination of Earth’s and moon’s gravity, it will need to burn very little fuel to keep moving.

The cameras will observe a vertical strip of the space stretching from the Earth’s pole to its equator in each orbit. Proceeding to the new neighboring strip in the next orbit, about twenty seven days later. It will take about one year to scan the heavens above the southern hemisphere and another year to finish the northern hemisphere. By the end of its two-year primary mission, it will have imaged roughly eighty five percent of the sky.

TESS will enable mankind to learn more about the other worlds. Certainly exciting times to be living in.

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Fiddle Dee Dee

by Ted Frimet

Fiddle Dee Dee

A complementary portal to an impressionists viewpoint

As most know, I am not an astrophotographer.

However false coloring does provide some interesting views into deep space by the Hubble Space Telescope.

And I had some time to fiddle with Photoshop.

I created an account at the Space Telescope Science Institute (stsci.edu), and went to the Mikulski Archive for Space Telescopes (MAST). There, they hold a variety of astronomical archives, for the public to access.

From MAST, I found the HST Data Search (http://archive.stsci.edu/hst/search.php) and loaded up on M51.

I pulled three images, J97C34XCQ, J97C34XEQ, and J97C34XGQ, imaged 2005-01-22, using the Hubbles’ Advanced Camera for Surveys (ACS).

They were closely related, enough, to provide some color contrast, when placed into Red-Green-Blue channels, in Photoshop.

GIMP, a free program could be used. However, I am in a new cycle of relearning Adobe Creative Suite – so this fit the bill – as it was already paid for.

What is really very cool, though, is the database not only gives RA, DEC, Exposure Time, Aperture and Instruments used, they also give a complete citation as to where to find where the images were used in scientific literature.

Just as it is found, here:

http://archive.stsci.edu/mastref.php?mission=hst&id=10452

I took the last three images in a series, that might be passable for use in three separate color channels.

The composite images appear below, “side-by-side”. The bottom one of course, was way manipulated in Photoshop.

Not very professional, in terms of astrophotography.

However, as a technique for an outreach class, this may have merit.

Sidereal Times readers: you decide if this is something we can do, for kids, or adults interested in Hubble, at some point going forward.

Who knows? By false coloring existing Hubble archives, your Outreach might even discover a “black hole”!

Best, Ted

P.S. – if you have a Mac, running High Sierra, the archive server required encrypted ftp protocols, which is not supported by Mac OS.

I am working with Apple to…ahem…get them to re-adopt encryption for ftp.

In the meanwhile, I found an inexpensive (free) alternative from the Apple Store, called “Forklift”. Works like a charm, right out of the box.

By the by – running an ftp session, out of DOS, in Windows 10, works just fine, too.

Posted in May 2018, Sidereal Times | Tagged , | Leave a comment

luminous distance

by Ted Frimet

how to ride a light beam

AAAP board member Gene Allen programmed outreach to a Scout Group, for Wednesday night, April 18th, at Bordentown, NJ. No problem, so I thought! These Scouts had an ulterior motive, though. The hidden secret agenda was star brightness and distance calculations. That is one tall order for any neophyte Amateur. Maybe not for our more experienced membership, of course! I realized that, for me, I had better break out the textbooks, and learn to turn a page. It turned out to be a lot of page turning!

I decided to brief the Scouts on a little history, with this essay, followed by some vocabulary. Then feature a basic, intuitive view into star brightness. And close with a luminosity distance calculation.

Astronomers continue to use a system that is based upon Hipparchus. (1) This Greek astronomer established a magnitude method over 2,000 years ago. In a nutshell, the larger the number, the dimmer the star. His simple system accounted for stars between 1st and 6th magnitude.

We keep Hipparchus’ system in mind, even today, and with a twist. In modern times, we speak of magnitude jumps. A 1st-magnitude jump is a brightness change of 2.5 times. A 2nd-magnitude jump is another brightness change using an extra 2.5 factor.

Using basic mathematics, we calculate that a 3rd-magnitude jump is:

( 2.512 x 2.512 ) = 6.310 times brighter than a 1st magnitude star.

Sometime in the 19th century, Astronomers further refined the brightness scale. We can now accommodate stars that are fainter than 6th magnitude. Under dark skies our naked eye limits reach 6th magnitude. The Hubble Space Telescope (HST) can see +30. Our club’s 14 inch diameter telescope can see stars about half-magnitude of HST.

Just a few weeks ago, I was at a dark sky site, at Jenny Jump State Park, trying to observe The Pinwheel Galaxy. This galaxy has a Messier name of M101. Messier was an Astronomer that noted all the fuzzy things in the night sky. One of our members can point out M101’s location to you, with a laser. However, at around magnitude 9, it cannot be seen with the eye. Even with a 10 inch telescope, it is diffuse and hard to spot. (2) Another source describes this Ursa Major resident at magnitude 7.9 (3). I could not view this face-on galaxy with my 12 inch Newtownian telescope, that dark night.

I might venture we could use low power binoculars to see the very diffuse Pinwheel. My friend and budding Astrophotographer, Captain James DiPietro, US Army NG, member UACNJ, managed to capture images with 90 second exposures. The human eye, being quite different from an electronically assisted astronomy (EAA), cannot build up photons, like Captain DiPietro’s camera. For us, EAA is the best way to view M101.

I did, however, manage to see her sister, M51, the Whirlpool Galaxy. It has since become my favorite, at 8.96 magnitude (4). You might ask, if M101 is brighter than M51, why could I not see it? Diffuse objects in the night sky are very hard for an amateur to see. M51 is more dense, with a size of 11’ x 7’ (arc minutes), 27.9 light years away.

M101 is 8.31 magnitude, 29’ x 27’ size, and 22.2 light years. An object may be closer, or brighter. That doesn’t mean we can view it more easily.

If you want to study a diffuse galaxy, you don’t want to use your highest power objectives. Use lower power to take in a greater field of view (FOV). Ask one of our observers to show you the Andromeda galaxy.

How bright a star is, is defined by absolute magnitude. This is how bright a star appears at a standard distance of 32.6 lightyears. Our sun, Sol, has an apparent magnitude of [-26.7]. Sols’ absolute magnitude is only 4.8 (5).

Astronomers calculate distances by the parallax method. That is, stars appear to move, and shift behind our closer nearby stars. By using math, really by using triangular geometry, you can figure out a distance to a star. According to the Astronomy Education Center at the University of Nebraska-Lincoln, the parallax method is good for stars out to 500 light-years.

We use the distance modulus to calculate even further stellar distances. You can estimate the stellar distance by subtracting absolute magnitude (M) and apparent magnitudes (m) (6) (7). However that is only a first step. We need to know both magnitudes, and apply logarithm math.

We know how to estimate apparent magnitude (m). We could do it, just like Hipparchus, and modify according to modern use. How then do we get absolute magnitude (M)? We measure it using sophisticated software. Or we can look up our numbers in Astronomy reference books.

A brightest stars table, listing 286 stars in all, can be found in the RASC Observers Handbook 2018, USA edition (8). There you will find m & M, as well as distances tabulated in light-years.

A more hands-on approach is to record the M, yourself. For this, we need to become astrophotographers, and make use of well designed telescopes, under dark skies.

One AAAP asset that we subscribe to is the Skynet Robotic Network. The University of North Carolina, Chapel Hill hosts the Skynet telescope system. Afterglow is their post-processing program. We use this software to sample absolute magnitude from astrophotography data. Take a picture of a star, using Skynet, then use Afterglow. Put your cursor on your star and Afterglow will record the absolute magnitude.

Researching the web, you can find many places to learn from. Some are easy to grasp, and some, like the below link, is just out of my learning curve:

http://astro.wku.edu/labs/m100/mags.html

Can we make this more simpler? Yes, we can!

Light intensity decreases as the distance squared.

Basically, the farther out the star is, the less light will reach your eyes.

If a star is 3 times farther out, then the light is 9 times less intense.

If a star is 2 times farther out then the light is 4 times less. Get it?

At the end of the essay you will find online references, and a bibliography for further study.

Now, here is your first distance modulus math calculation:

m – M = (11.13 – 15.56) = -4.43

-4.43 ==> d

d = 1.300 parsecs

parsecs to light years conversion:

Distance = 1.3 parsecs = 4.24 light-years

parsecs to light years (9)

How we derive “d” from the magnitude difference is complex. If you like, you can read below. And we will discuss in detail how we get from m-M to d.

Here is some data (10), taken from a table of nearest stars from The Observers Handbook:

Proxima Centauri

apparent magnitude (m) = 11.13

absolute magnitude (M) = 15.56

ly (light years) = 4.24

Sirius (A)

m = -1.43

M = 1.47

ly = 8.58

Let’s calculate how far Proxima Centauri is. You may recall, from your Scout research, that this red dwarf star, is Sol’s closest neighbor. It is mentioned in this months essay (11), “go fly a kite”, as the Breakthough Starshot Intiative’s destination. Read more, here:

https://princetonastronomy.wordpress.com/2018/04/02/go-fly-a-kite/

Need the math? Ok. Here we go. Hang on!

Proxima Centauri m = 11.13 and M = 15.56

m – M = -5 + 5 log10(d)

11.13 – 15.56 = -5 + 5 log10(d)

-4.43 = 5log10(d) – 5

Using a wiki reference to isolate “d” (retrieved April 3, 2018)

https://en.wikipedia.org/wiki/Distance_modulus

Here, I mean that d = 10↑(distance modulus / 5) + 1

where “↑” means raised to the “power of (distance modulus / 5)”

then add 1 to the answer.

d = 10↑(-4.43/5) +1

d = 10↑(-.886) + 1

d = 0.1300169578 + 1

d = 1.3 parsecs

Distance = 1.3 parsecs = 4.24 light-years

If we check with our RASC reference, our distance to Proximus Centauri is confirmed.

We have calculated a distance to a star, by using the available light.

Now it is time to take notice that Sirius, the dog star, is much brighter than Sol’s closest stellar neighbor. Yet doing the math, we conclude that Sirius is 2/3rds (67%) farther away from us than Proximus Centauri. You have now proved that just because something is brighter, doesn’t necessarily mean it is closer. We will continue to plan on

dealing with star brightness as a function of distance. To do so, we must include both magnitudes types (little m & big M) in our calculations.

By happenstance, I had an opportunity to attend a lecture, this Friday afternoon, April 6th at The University of the Sciences, Philadelphia, Pennsylvania. Today’s guest lecturer was Erica Ellingson, PhD. Dr Ellingson is from the Department of Astrophysical & Planetary Sciences, University of Colorado; Fellow of the Center for Astrophysics & Space Astronomy. I was met there by fellow AAAP member and Program Chair, Ira Polans.

Regretfully, Philadelphia traffic barred me from Dr Ellingson’s first lecture. I did manage to squeeze in a slice of pizza, and the second seminar topic: Dark Energy and Cosmology. Although the topic was well presented and lucid, I’d like to bring out an important side note, touched upon by our lecturer: the Type 1A Nova.

During the seminar, I was reminded that there is a rare chance of a nova in galaxy. And if we group hundreds of galaxies together, for study, we will see many of them. One in particular is of stellar importance to luminous distance measurement. It is the Type 1A supernovae.

The absolute magnitude of a Type 1A is ALWAYS the same luminosity. However, the apparent magnitude, which varies by distance, is not always the same. If you apply the distance modulus math, you can calculate the distance to the parent galaxy. That is, you can tell the distances to stars, galaxies, and the great spaces between them all.

I would venture to say, if you hang around long enough, a Type 1A will show you how to ride a light beam; right up to the edge of what is the visual horizon of our 14.7 billion year old Universe.

Notes, resources and bibliography: (all links retrieved April 3, 2018).

There is an online distance modulus calculator hosted by University of Nebraska-Lincoln. Use it to check your work.

http://astro.unl.edu/naap/distance/distance_modulus.html

With greater ease we can review a Cornell University online document. It has plenty of math, and sample data to use.

http://www.astro.cornell.edu/academics/courses/astro1101/lectures6StellarDistancesRev1.pdf

For more information, you can read here, at Swinburne Astronomy Online:

http://astronomy.swin.edu.au/cosmos/D/Distance+Modulus

A second math approach to calculate luminosity distance (12):

https://en.wikipedia.org/wiki/Luminosity_distance

M = absolute magnitude

m = apparent magnitude

Luminosity distance: DL (written as D)

M = m-5(log10 D – 1)

D = 10↑(m-M/5) + 1

distance = 10↑(11.13 – 15.56)/5) + 1

distance = 10↑(-4.43 / 5) + 1

distance = 10↑(-.886) + 1

distance = .130 + 1

distance = 1.30 parsecs

https://www.metric-conversions.org/length/lightyears-to-parsecs.htm (13)

pc = ly * 0.30660

ly = pc/.30660

ly = 1.30 / .30660

ly = 4.24 ly

  1. Harrington, P. S. (2003). Star watch: The amateur astronomers guide to finding, observing, and learning about over 125 celestial objects. Hoboken, NJ: Wiley. pps7-8
  2. Burnham, R., Dyer, A., Garfinkle, R., George, M., Kanipe, J., Levy, D. H., & O’Bryne, D. (2002). A guide to advanced skywatching: The backyard astronomers guide to starhopping and exploring the universe. San Francisco, CA: Fog City Press., p234
  3. Sparrow, G. (2015). The stargazers handbook: The definitive field guide to the night sky. London: Quercus., p32
  4. Madore, B. F., & Steer, I. (2018). The Royal Astronomical Society of Canada Observer’s Handbook (2018 ed., 110th year of publication – RASC) (J. S. Edgar, Ed.). Canada: Webcom. Observer’s Handbook 2018 USA Edition. Galaxies Brightest and Nearest, p333
  5. Burnham, R., et al, ibid, p162
  6. Burnham, R., et al, ibid, p163
  7. Bishop, Roy (2018), RASC, et al, Some astronomical and physical data, p31
  8. Karmo, Toomas, Corbally, Chris, & Gray, Richard (2018), RASC, et al,
    The brightest stars, pps 275-283
  9. Google web search April 3, 2018: “Parsecs to Light Years” conversion:
    https://www.google.com/search?client=safari&rls=en&q=parsecs+to+light+years&ie=UTF-8&oe=UTF-8
  10. Henry, Todd J. (2018), RASC, et al, The nearest stars, p289
  11. Frimet, T. R. (2018, April 02). Go fly a kite (S. Agarwal & P. Ganti, Eds.). Retrieved April 03, 2018, from https://princetonastronomy.wordpress.com/2018/04/02/go-fly-a-kite/
  12. Luminosity distance. (2018, February 28). Retrieved April 03, 2018, from
    https://en.wikipedia.org/wiki/Luminosity_distance
  13. https://www.metric-conversions.org/length/lightyears-to-parsecs.htm Retrieved April 3, 2018. Wight Hat Ltd. ©2003-2018. Their page last updated: Thr 22 Mar 2018
Posted in May 2018, Sidereal Times | Tagged , | Leave a comment