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Location: Great Boreal Deciduous Hardwood Forest, New England, United States

old dude, all hair, swell new teeth

13 April 2006

Before you book your trip, read about the places you'll see!

Clicking usually makes things better.

This I swear to you:
Someday human beings -- women and men AND children from Earth -- will get to these places. Maybe you and I will all be Long Dead. But It Will Happen.

We have to go there. The first humans to get there will get there for Pure Nosiness, for the unquenchable Human Obsession To Know.

Later will come the Industrialists and the Bureaucrats, and the Food Service Providers.

Maybe eventually Pirates. Please de-frost me and whisper in my disoriented ear when this happens, I want to hear all about The Space Pirates.

ARE YOU READY? Have you bought your Vleeptron Guide to the Stars? One of the first Charter Tours will surely be The Big Dipper Tour, an unforgettable journey from star to star in the most famous of all our Constellations. Read about the different Stars you'll see before you go.

You don't want to get to Alioth and discover they don't take Visa or Mastercard. On Dubhe-6, you have to constantly scream Voo! Voo! or you'll be forceably married to a Xqznnnnnn. Read this and learn the important local stuff in advance.

How far away are these stars? That's been the most difficult of all astronomical questions for us to answer. Hubble discovered one of the first tools which worked to answer this mystery. (Before Hubble, the most precise answer was "That star is Very Far Away.") Hubble's distancing tool is called the Cepheid Variable star.

Here's the problem, essentially. All stars are so far from us that even with telescopes, we can only see most of them as bright pinpoints. Stars range dramatically in intrinsic (local) brightness (as opposed to apparent brightness, how bright we see them).

From Earth, how can we tell the difference between a very bright star that's very far away, and a much dimmer star that's much closer?

The standard introductory experiment is a football field on a very dark moonless night. Flashlights of very different powers are placed all over the field, all pointing at one end of the field. Students at that end have to make estimates, best guesses of what yardline each distant flashlight is actually on.

Night highway driving also requires us to figure out how far away oncoming headlights of various strengths are. It's a common experience to seriously misjudge how far away the headlights are. I used to know an idiot who drove a huge overpowered car very fast day and night, and paid hundreds of dollars for superpowered halogen headlights (which were way illegal).

We could figure out the distance to a star much more easily if we could use the huge distance which is the major axis of the Earth's ellipse orbit, and measure the different angles to the same star at one point, and then re-measure the angle six months later. This trigonometry tool for measuring the distance of far-away objects is called Parallex. But we can't use Parallex because even the nearest stars are so far away that we can't get any useful answers from the infinitessimally tiny difference angles -- the huge distance between where Earth is six months apart is still far too tiny to use to compute the distance to even nearby stars, and even more useless to compute the distance to other galaxies. I can draw you a picture if you want me to.

So Vleeptron is proud to present the first installment of the Vleeptron Guide to Stars Visible from Earth. All this is shamelessly filched verbatim from Jim Kaler, Prof. Emeritus of Astronomy, University of Illinois (at Urbana-Champaign, the campus that solved the Four-Color Problem).

What would you pay
to take
the first Voyage
to the Big Dipper?


If you think it's a bad idea to use our intellectual and societal and physical resources to travel to the Stars, what do you think is a better thing to do with our intellectual and societal and physical energies?

You bet, feed and give good health and peaceful security to everybody. Vleeptron is way down with that.

But we've never done a very good job at that. All over Earth, the people who actually make the priorities decisions have never been wildly enthused about major improvements in providing health, food and physical security.

Mostly wars prioritize our societal and economic and political resources. Every time Bush cooks up a war, the war must come first, and it just sucks the living shit out of our desires to improve health or education or the substandard, ailing, wheezing national and international infrastructure.

And space exploration is always the first to suffer. One war forward, three planets back.

Our Priority One is the most shameful thing a society can do.

The most enlightened, civilized and humane things humans can do -- that's Priority twelve or nineteen or thirty-five.

* * * * *

Voyage to Every Star
in The Big Dipper
with Vleeptron Galactic Tours!

A Holiday You'll Never Forget!

Including visits to
the surface of Nine
Reasonably Habitable
Planets
& Four Moons!

NOTICE: Travel Insurance does NOT reimburse travellers or their survivors from hostile acts by Space Pirates.

Oh the Places You'll See!

* * * * *

ALKAID (Eta Ursae Majoris). Though the name may not be so well known, the star certainly is, as Alkaid is the end star in the handle of the Big Dipper, the great asterism that makes most of the grand constellation Ursa Major, the Greater Bear. Just fainter than Dubhe, the front bowl star of the Dipper, second magnitude (1.85)

Alkaid is the third brightest star in the constellation and places number 35 in the list of the brightest stars. Though Johannes Bayer generally listed stars by Greek letter names in order of brightness within a constellation, the stars of the Dipper are named from west to east, rendering Alkaid Eta Ursae Majoris rather than Beta. Different cultures see the sky differently as well. Alkaid's Arabic name means "the leader," and appears to refer to the "daughters" (the handle of the Dipper) that stand by a funeral bier made of the Dipper's bowl. Alkaid is also known as Benetnasch, which also refers to the daughters.

Alkaid is almost exactly 100 light years away. With a surface temperature of about 20,000 degrees Kelvin, is one of the hotter stars that can be seen with the naked eye, and therefore glows to us a soft blue-white. Like the Sun, it is a "main-sequence" star that shines by fusing hydrogen into helium in its core.

However its mass of six times that of the Sun renders it both hotter and over 700 times more luminous. Were Alkaid our Sun, we would have to be 25 times farther away to survive, almost to the orbit of Neptune. It one of the two renegades of the Dipper. The five middle stars are all moving through space together as part of a loosely bound cluster. Alkaid and Dubhe, however, are moving in their own directions, ultimately dooming the Dipper's shape.

The star is just below the temperature limit at which stars produce strong X-rays as a result of shock waves in their winds, and is therefore only a weak source of X-rays.

MIZAR (Zeta Ursae Majoris). One of the most famed stars of the sky, second magnitude (2.06) Mizar, 78 light years away, is the Zeta star of Ursa Major, the Greater Bear, the second star in from the end of the handle of the Big Dipper, and the Dipper's fourth brightest star. In large part its fame comes from the coupling of the star with a nearby visual companion, fourth magnitude Alcor, only 12 minutes of arc (a fifth of a degree) to the northeast. The two, Mizar and Alcor, termed the "horse and rider" by the Arabians, are a good test of minimal vision. The star's Arabic name derives from a word meaning "the groin" of the celestial Bear that plods silently around the north celestial pole (the name mistakenly drawn from Merak, in the Dipper's bowl).

However even without Alcor, Mizar takes its place in the celestial hall of fame as the first known "double star," one that consists of a pair of stars that orbit each other. Found to be double in 1650, Mizar is a prime target for someone with a new telescope, as the components are an easy 14 seconds of arc apart (at least 500 astronomical units), the two taking at least 5000 years to make their orbit about each other. More remarkably, each of these two components is AGAIN double. The brighter of the two (magnitude 2.27) contains a very close pair a mere 7 or 8 thousandths of a second of arc apart (an angle made by a penny at a distance of 300 miles) that has an orbital period of 20.5 days; the fainter of them (magnitude 3.95) contains a pair with a period of about half a year. Mizar is thus actually a quartet of stars, a double-double. It is moving through space together with its more-distant companion, Alcor. Mizar and Alcor together therefore probably make a quintuple star, Alcor taking at least 750,000 years to make a single round trip around its quadruple companion.

All of the stars are similar, all "main sequence" hydrogen-fusing stars like the Sun, but of white class A (the brighter both A2, the fainter probably both A5 or A7) with temperatures ranging between around 7500 and 9000 degrees Kelvin and luminosities from 10 to 30 times solar. The orbit of the brighter double that makes Mizar has been observed with a sophisticated "interferometer" that makes use of the interfering properties of light. Analysis shows the component stars to have masses 2.5 times that of the Sun; the masses of the fainter pair are estimated at around 1.6 solar.

The stars have odd chemical abundances as a result of slow rotation, which allows for quiet atmospheres and chemical separation. The brighter of the pair seen through the telescope is rich in silicon and strontium, whereas the fainter is a "metallic line star" that is deficient in aluminum and calcium but high in silicon and in rare earths like cerium and samarium.

ALIOTH (Epsilon Ursae Majoris). The graceful curve of handle of the Big Dipper (the Plough in Great Britain), among the most famed of celestial sights, represents the tail of Ursa Major, the Greater Bear. Third star in from the end, "Alioth" relates not to a bear, but to a "black horse," the name corrupted from the original and mis-assigned to the naked-eye companion of Mizar, which took on the vaguely similar name "Alcor." Bayer's rough rule of assigning Greek-letter names more or less in order of brightness is quite violated here, as the Bear's bright stars are named from west to east, hence "Epsilon" for Ursa Major's brightest (bright second magnitude, 1.77) star, indeed for the 32nd brightest star in the whole sky.

A white class A (A0) star with a measured temperature of 9400 Kelvin, Alioth shines at us from a distance of 81 light years with a luminosity 108 times that of the Sun, from which we derive a diameter of four times solar and a mass close to triple that of the Sun. Large and luminous for its class, Alioth is probably ageing, and is nearing the end of its main sequence hydrogen-fusing lifetime.

Of greater significance, Alioth is the brightest of the "peculiar A (Ap) stars," magnetic stars in which a variety of chemical elements are either depleted or enhanced, and in addition appear to change with great regularity as the star rotates. "Chemically peculiar" behavior in class A and B stars generally comes not from creation of elements, but from their separation in the relatively thin stellar atmospheres, some falling downward within the star's gravitational field, others lofted upward as a result of an outward push by radiation. Here, they are also apparently related to the Alioth's magnetic field.

Alioth is classed as an "Alpha Canum Venaticorum" star (after the prototype, Cor Caroli). Its magnetic field -- and the chemical composition -- change from our perspective during the star's 5.1-day stellar rotation period. Some elements are highly concentrated into distinct regions that swing in and out of sight as the star spins. For example, the abundance of oxygen is 100,000 times greater near the magnetic equator than near the magnetic poles (which are displaced from the rotational equator and poles); chromium behaves similarly. Heavier elements, such as the rare earth europium, also display strong variations. Though visually the brightest of the peculiar A stars, Alioth is also noted for having one of the weakest magnetic fields among its class, only about 100 times that of the Earth, 15 times weaker than that observed for Cor Caroli.

PHECDA (Gamma Ursae Majoris). Few figures in the sky move us more than the Big Dipper, its seven bright stars laid out in a long bent row that the British call the Plough. All but one of its stars are second magnitude, though Phecda, the third one in from the end of the bowl, and southernmost of the bowl stars, is just on the edge of third (2.44). Though it ranks sixth in brightness in the Dipper, indeed in the whole parent constellation, Ursa Major (the Greater Bear), Phecda still received the Gamma designation from Bayer, who simply lettered the Dipper stars from front to back, the brightest (Alkaid) getting Eta.

The name refers directly to the Bear; Phecda is a rough re-pronunciation of the Arabic word that means "thigh," reflecting the star's placement within the Bear's hindquarters. The five middle stars of the Dipper are all part of a group, a loose open cluster of stars (the Ursa Major Cluster) whose members are moving through space together. (Dubhe and Alkaid, at the Dipper's ends, are not a part; the result will be the Dipper's eventual dissolution.) All about the same distance away from us, Phecda, at 84 light years, is just barely the most distant of the five.

They are the collective centerpiece of a much larger structure called the Ursa Major Moving Group that, among many other stars, includes Sirius, and is about 300 million years old. Like its Dipper counterparts, Phecda is a class A (at the hot end of A, A0) main sequence dwarf, a common hydrogen-burner like the Sun (though Alioth -- Epsilon -- is probably close to burning out). Phecda is a white, "colorless," star, meaning that it appears the same relative brightness in a photograph as it does to the eye. With a temperature of 9500 Kelvin, it radiates 64 times as much energy as the Sun from a surface three times the solar diameter, from which we infer a mass about 2.7 times solar. Phecda's spectrum reveals evidence for a close companion, but we have no idea of what it is like other than that it is faint and of little consequence.

Phecda's greatest claim to stellar fame involves emissions from hydrogen that tell of a circulating cloud or disk of spinning gas, making it formally an "Ae" star. Most stars that behave like Phecda are hotter, in class B (which stretches from just over 9500 Kelvin to 30,000 Kelvin). Such "Be stars" are fairly common, and include Achernar, Alcyone, and (at the extreme) Gamma Cas. All are rapid rotators, the fast rotation probably the cause of the spinning cloud that surrounds them. These "emission stars" extend coolward into class A, but they are rare; only about 100 Ae stars are known. Phecda, rotating at least at 168 kilometers per second at its equator, 84 times faster than the Sun, is the brightest. There is no evidence of any dust cloud that might hold planets, a pity as the other Dipper stars would present quite a sight. From Phecda, Merak (the Beta star) would look like Sirius does in our sky. In the opposite direction, the stars of the handle would be strung out like bright jewels along wide string.

DUBHE (Alpha Ursae Majoris). Almost first magnitude, shining for us at the front of the bowl of the Big Dipper in Ursa Major, the Great Bear, Dubhe (the "h" silent, the final "e" pronounced almost any way you wish) leads the Dipper in its northeasterly climb above the horizon.

The Arabic name means "the bear" itself, and comes from a longer phrase that indicates the star's location on the back of the Great Bear. Though not quite the brightest of its constellation, just two percent short of Alioth (the Eta star, third in from the handle), Dubhe received the Alpha designation when Bayer simply lettered the Dipper's stars from west to east, from Dubhe to Alkaid, the latter bringing up the end of the bear's tail.

Together with Merak, the Beta star, Dubhe makes the famed "Pointers," which lead north to the North Star, Polaris. In the other direction they point toward Regulus in Leo. As appropriate for the Dipper's lead star, Dubhe quite stands out among the others that make the famed figure. The middle five stars, which include Mizar along with its little companion Alcor, are all warm class A stars that are part of a physical cluster all about 80 light years away. Dubhe, however, is not a part of the system (nor is Alkaid), and is half again as distant, 124 light years, and the most distant of the Dipper stars.

As a class K giant with a temperature of 4500 Kelvin, it is also the coolest of them (its orange color easily noted), and the only one that is evolved and in the long process of dying, though for now it is temporarily stabilized by the fusion of helium in its core. With a luminosity 300 times that of the Sun, Dubhe is the second most luminous of the seven stars, topped only by hot Alkaid, the luminosity and temperature implying a radius 30 times solar. Dubhe is orbited at a distance of about 23 Earth-Sun distances (somewhat greater than the distance between Uranus and the Sun) by a warmer and much dimmer and less massive class F star that takes 44 years to go around.

Someone riding a planet orbiting the F star would see vastly brighter Dubhe as second orange sun with about half the brightness of the Sun in our sky. Over 400 times farther away is another class F star that also has a companion (with a six- day period), from which Dubhe would appear as a brilliant orange star over 10 times brighter then Venus, making a total of four stars in the system. The Dipper's middle five stars are all moving together, while Dubhe and Alkaid are going in the other direction, the Dipper destined to fall apart over the next tens of thousands of years.

MERAK (Beta Ursae Majoris). High in the sky in northern spring evenings, just climbing above the northern horizon in southern hemisphere autumn, the Big Dipper -- the "plough" in England -- is among the most recognized and recognizable of figures, one of the first learned in a quest to know the constellations.

Leading the westward moving parade are Dubhe at the lip of the Dipper's bowl and Merak, also at the bowl's front and just to the south of Dubhe, the two making the Big Dipper's "Pointers" that lead the way to the North Star. While often considered a constellation, the Dipper is a small part -- an asterism -- of the ancient figure of Ursa Major, the Greater Bear, much of which is circumpolar, never setting for far northerners. The names of all but two of the Dipper's stars (Alioth and Alkaid) refer to the Bear, "Merak" coming from an Arabic description that means "the flank of the Greater Bear."

The two front bowl stars make a nice contrast, Dubhe a cool orange giant, Merak a seemingly standard hot (9000 Kelvin) white class A (A1) "main sequence" dwarf star, one that is quietly fusing hydrogen to helium [in] its core, as does the Sun. With an apparent magnitude of 2.37 (faint second), Merak ranks fifth in brightness in the Dipper, right after Mizar in the figure's handle. In spite of its ranking, however, it received the Beta designation from Bayer, who lettered the Dipper's stars from front to back.

From its distance of 79 light years, Merak's luminosity is seen to be almost 60 times solar, its mass about triple that of the Sun. While these class A stars are not all that common, they are bright enough to be seen at large distances and thus seem disproportionately numerous in nighttime sky. Merak has two special features that set it off from the others. Like Fomalhaut and some others, it is a Vega kind of star, one that radiates extra infrared light that seems to be coming from a disk-like shroud of heated dust, one reminiscent of the dusty disk that produced our planets. Merak's detected disk approaches the orbit of Saturn in size, the dust particles having temperatures of a few hundred degrees Kelvin, similar to that found in our own planetary system.

Does the star have planets too? We do not know.


Merak is also a prominent part of the Ursa Major Cluster, as are all the Dipper's stars but the two at the ends, the middle five all class A stars about the same distance away. The sight from one of Merak's planets, were it to have any, would be quite lovely, the five easterly stars of the Dipper all "zeroth" magnitude or brighter within a 25 degree-wide segment, the middle three stars of the handle (Megrez, Alioth, and Mizar) clumped into a small brilliant triangle.

4 Comments:

Anonymous DespicableTeacher said...

Oh well, we will long be dead, but I bet you one of the first things to be built will be a McDonald's, so «Earthlings» will feel at home!

21:14  
Blogger Jim Olson said...

I want to be the first Christian pastor in space. I want to look at the beautiful blue marble that is our home out the window of a space ship and see our planet the way I think God sees it. Funny that you can't see lines between countries from space.

22:44  
Blogger Bob Merkin said...

my handle on CB back during the CB craze of the late 1970s was Space Rabbi.

i mean, we KNOW there are going to be clergy in space. the only mystery is: Who will get to be the first ones?

My advice: Keep doing all the clergy stuff you're doing ... but take flying lessons on weekends, and get the most advanced pilot's license you can as fast as you can. Your application will be considered for (a.) Spirituality and (b.) competency in air and space technology. Cover both bases.

00:11  
Anonymous patfromyouknowwhere said...

eh, have you seen these cool new images from Venus and Mars yet? Have you heard about the japanese plans that they want to send an Orbiter to the Moon ?
Since it looks like the Zeta Beam will be repaired anytime soon this is probably the only option to get out of this bloody mess for a while (and I could be the third Swiss in Space)
Do you take credit cards ? How about Cable TV on the Coach ? What 'bout the Food ? Will the voyage also include daytrips to Mars and Venus ? Can i bring along my collection of X Munis One episodes for onboard entertainment or are we just going to listen to The Dead all day long ? And most of all; WHERE CAN I SIGN UP ????

14:02  

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