M 44, the Beehive Cluster in Cancer - also called "Praesepe" (Tomahide Nakaegawa) http://www.ne.jp/asahi/nakaegaw/piz/)
Season: Well, it's "summer" at last over 50 North. Of course, it won't really begin until mid-April. And then its over usually well before 21 September. (Pull those shades down at your summer dachas.)
(Biography: Steve Yaskell is a science author in astronomy and natural history. His articles and insights have appeared in many publications around the world, such as Great Britains' Astronomy Now, as well as Sky & Telescope and The Sciences in the USA, among others. He recently co-authored a book on solar astrophysics and severe global climate change at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, USA. [The Maunder Minimum and the Variable Sun-Earth Connection, WSP:2004])
NAR obtains permission to use material by solicitation. If NAR cannot obtain it at web addresses, NAR publishes with the proviso that NAR will remove it instantly if the discovering author(s)so wishes. All reasonable efforts to contact content contributors are made by NAR. If you wish to reprint articles in whole or part, please obtain permission from NAR. Or drop NAR an email at starthrower1@msn.com. Clearance for rewriting and editing timely news material from Science Magazine was granted by Elisabeth Sandler at the American Association for the Advancement of Science(esandler@aaas.org). This rule generally holds for most scientific journals.
________________________________________________________________
Regular quarterly features
*The quadrant
*Star hopping with
small telescopes (Beehive in Cancer, and a careful pat on the lion's head.)
(Steven H. Yaskell)
*Star hopping with
large telescopes (Galloping galaxies with Darrell Abrahams.)
*Coordinates over
50○ N (Sun, Moon, Moon phases and the planets.)
*NAR guest feature
(As a matter of fact, you may be interested in new matter: the Scenario Machine)
(Vladimir Mikhailovitch Lipunov of Moscow State University and the Sternberg
Astronomical Institute and his team offers you some summertime parameter games.)
*Astronomical
science news (Heard the one about the dinosaurs, the asteroid and the
dinoflagellates? - hard evidence at last connects to life: Russian scientist's
simulations explain the plumes in black holes.)
*In
astronomical history (The late, great transit circle.)
*Equipment
review (The Sovietski 6 inch...the Russian telescope that doesn't look like
"it's ready to kill something.") (Ed Ting)
*Holy Spring
(A poem by Dylan Thomas.)
The quadrant
\\\ Time to defrost and put on
sunglasses______________________________________
I don’t have any idea how
many of you choose to rough it in a backyard or on a hillside without some kind
of wind breaking technology when you observe. Alternately I can’t picture you
sensible ones who use remote devices when you stargaze since I’ve never used any
(yet). If I ever get to, it’ll be an old age project. Those of you with homemade
observatories I won’t bother to mention. (You’re too smart for all of us.)
I’m one of those who
actually sits on a balcony at 59 North in the winter dressed like an Inuit
waiting by a seal hole in the snow with his spear. It is dark and it is cold.
Fortunately I have a banister that blocks my neighbor’s lights and most
importantly, the wind which never stops up here. I can run into the livingroom
after half an hour or so of scanning my east to southwest view. If I want to
look north, I have to set up below past the apartment complex’s common washroom
and sauna, which abuts a pleasant garden kept by a neighboring couple.
Of course in late February,
that pleasant garden is a garden of ice and stone and can be so throughout
March, as well. This is the reason why I withhold all my north sky rambling
until late March, when, by the end of the month or by April it is tolerable to
stand outside for an hour at a time. Then I have a month left to whirl through
Cassiopeia and Perseus since by April’s end true darkness ends up here. The
midnight sun comes in. Those of us above or near 50 North will have many
pellucid yellow and eggshell blue nights until mid July or, as in my case, by
the time of the Perseid meteor shower in mid August.
Generally this is a time to
pursue other things in astronomy, rather than observing. Like starting that book
you wanted to write on comets, for instance. Or polishing a blank by hand for a
neighbor kid’s science project in building a small reflector. Sun and Moon
observers have fun, solar astronomy and selenology two endless pursuits in
sub-Polar eternal summer brightness. It’s time for mosquito repellant and lazy
afternoons in the Sun, on a towel or in a canoe, dangling a fishing rod. As the
Sun sets think of all that solar insolation which is tanning you, and by so
doing, contemplate the discovery of gravitational waves. Dr. Vladimir Lipunov,
our guest feature astronomer this issue, hailing from Moscow State University in
Russia, has done this with a tool he and his associates developed. There are
several projects already ongoing to detect these from different places, some of
which Lipunov prompted into being with his research (ACIGA in Australia, GEO600
in Germany, LISA in the USA/EU, TAMA 300 in Japan, and the Italian-French Virgo
project, for instance).
Perhaps the LIGO site sums
it up best:
The detection of
gravitational waves from astrophysical sources is probably one of the most
keenly awaited events in the history of astrophysics…Albert Einstein predicted
the existence of these gravitational waves in his 1916 general theory of
relativity, but only now in the 21st Century has technology advanced to enable
their detection and study by science. Although not yet detected directly, the
influence of gravitational waves on a binary pulsar (two neutron stars orbiting
each other) has been measured accurately, and was found to be in good agreement
with original predictions.
Among things the existence
of gravitational waves might reveal are births and disappearances of neutron
stars into black holes, if not the existence of black holes themselves, among
others (for instance, a glimpse at how space-time began). But also, as Dr.
Lipunov points out, the discovery of new matter, altogether, is predicted. Those
of you who are mathematically inclined are invited to visit Lipunov’s site at
the links provided in his fascinating article and to work out some parameters.
Let’s tip our glasses to
the Russians this summer, who’ve made this northern issue complete. Outside of a
look into galactic space much deeper than I can perform (thanks to Canadian
Darrell Abrahams, armed with his 16.5 inch goliath) we have a hot, verbal
clarion call unto this arctic “summer” (is there ever a “spring” up here?) by
the “Lion from Wales” (Tom Jones is the “Bull”) – the poet Dylan Thomas.
Now go get those sunglasses
out for the long summer made longer by the “white nights.” Bask in the
irradiative effervescence, those "arrows of pure fire," drink your favorite
drink and stay cool. We’re children of the cold, having emerged from grasslands,
yet mastered snowdrifts. This means that a hot summer is something to endure.
But it is also something to indulge in and enjoy.
Steve Yaskell
Star hopping with
small telescopes
10th hour: Leo’s
”coeur” through Cancer
Steven H. Yaskell
Spring means arctic
twilight returns to the 50th parallel and above; indeed to the whole hemisphere.
Heavy coats come off. Daylight started to increase well before 1 January. As
Northern Europe cloud cover leaves in March, and harsh polar “white nights”
return everywhere else above 50 North including Alaska and Kamchatka Peninsula
we bet heavily on clear, warmer nights until April’s end. By mid-May only radio
or daytime astronomers operate. Visual silver-on-black-velvet observing is
limited until mid August.
We all love dark sky
observing. It is more than a shame that it is so rare above Fairbanks, Alaska,
St. Petersburg, Russia, and Stockholm, Sweden. Melting snow and the smell of
life covers the ground and fills the evening air. After 1800 and until at least
2030 throughout March, Leo (the lion) spreads in full glory across the
Southeastern sky. Leo fills the gap left months ago by bright Orion – only
higher northeast.
Find Alpha Leonis (Regulus)
- the Lion’s “Coeur” – or “heart” - at 10h 8m 22.3 s (right ascension) +11
degrees, 58´ and 02´´ (declination). It is the big star marked on Leo in the
star map. Regulus is a helium star with a quite powerful visual (apparent) +1.34
magnitude. Richard Hinckley Allen in 1899 reported that Medieval Europeans
thought the star meant royal birth.
Nine degrees of arc
northwest of Regulus at + 20 find Algieba (Gamma Leonis). You are now “getting
inside the lion’s head” so to speak. Five minutes northeast lifts you to
MuLeonis. Mu Leonis and Epsilon Leonis (lowered 4 minutes southwest of Mu
Leonis) to the Persians meant “Ras el Asad” or the “head of the lion,” Mu being
the northern star and Epsilon being the southern in the lion’s head. Gamma, Mu
and Epsilon are all around +3 - +4 visual magnitude. But even in Stockholm’s and
Fairbank’s and St. Petersburg’s light pollution they can be seen forming a
triangular hook beginning with Algieba (“lion’s mane”) up to Zeta Leonis, on to
Mu, then down to Epsilon. Zeta Leonis is very near to the radiant of November’s
annual Leonid meteor shower. (The last great one was in 1966, way before many of
us were born.)
Jumping off 3rd magnitude
Lambda Leonis (west of Epsilon) move from 10h 40m right ascension (r.a.) over to
9h 40m r.a. - from about +22 degrees down to +20 degrees. Now find yourself in
the center of Cancer and Messier 44 (M 44) – the Beehive Cluster.
Cancer is the least visible
zodiacal constellation. However, Messier’s probable 44th “object to avoid” (to
his comet-hunter’s thinking) opens the crab’s belly up to us. It is an open
cluster some 500 light years distant and is still called by an old Latin word
Praesepe (“little bed”). It is best seen in image stabilizing binoculars or at
low power (say, around X 40) in telescopes. In binoculars look for how it seems
like a beehive. It is bulb-like, thicker in the middle, with random stars
seeming to spin around it, just like bees. M44 gives me a greenish and yellow
impression in binoculars – like a real crab. (But this could be due to my
forty-seven year old vision.) A Lumicon Deep Sky filter’s 90-100 nanometer
bandpass brings out the beehive’s light and intensifies the experience.
As we finish the star grid
this time round, take a look way off behind the “tail of the lion” to the south.
If you see stars that form a two-towered radio antenna of +3 magnitude stars
like buttons in the sky, you are looking at Melotte (MEL) 111 (at 12h 20m over,
c. +24 up) an open cluster that dwarfs M44’s seconds of 80 arc sky coverage. It
lies in “Berenice’s Hair” - Coma Berenices.
Star hopping with
large telescopes
Spring's galactic
rush hour
Darrell Abrahams
As a fruit and vegetable
gardener, spring is my most hurried time. Trees and vines must be pruned, weeds
pulled, soil prepared, seeds planted and seedlings transplanted. All this must
be done in the wet and rainy conditions of a Canadian west coast spring. The
same can be said for the astronomical viewing of the northerner's spring.
In the autumn as the nights
get longer, the fall night sky seems to hardly change. Just as the turning night
sky advances west about four minutes earlier each evening, the fall sunset and
twilight ending times also recede. This results in a lingering of the same
constellations if one continually observes one or two hours after the receding
sunset.
The opposite problem
happens in the northerner's spring The later sunset times quickly eat into our
observing of the spring night sky and before we know it, twilight has consumed
our whole early summer sky. Add to that the weather on my “wet coast2 and I'm
always rushed in my planned spring observing.
And spring observing is
galaxy hunting time. All those lovely and unique galaxies that ride the sky due
south of the Big Dipper in Coma Berenices, Canes Venatici, Leo and Virgo. These
include the Virgo Galaxy Cluster riding the Coma-Virgo constellation boundry.
But where to start? Many succumb to not identifying them and wind up enjoying
them by just surfing, scanning, and panning across the area with oohs and aahs
but with no real idea of what they're seeing. Others, with large apertures, have
fun trying to find the area that has the most galaxies in one field of view.
This too is enjoyable, but like watching the different types of birds visiting
the bird feeder, they're only just pretty birds until one learns their names,
varieties and differences.
Galaxy hunting in the Virgo
Cluster is a bit like going swimming in a cold mountain lake. It's not something
you can wade slowly into while holding someone's hand. You must either run, jump
or dive in. It's very invigorating. Just like galaxy hunting. So I recommend you
start with a good chart. My first serious dive into the Virgo Cluster was
several years ago with my home built eight inch f 8 Newtonian. It was before I
owned a copy of the Uranometria 2000 Deep Sky Atlas and my detailed chart of the
cluster was a freeware copy of Hallo Northern Sky. With the software I was able
to select only the galaxies up to my chosen limit of about magnitude 11.9 I had
printed and literally cut and taped together a large close-up chart of the Virgo
Cluster and rolled it into a tube.
Out in the dark, my
sidekick Rick and I then started near Epsilon Virginis and worked our way west
through the few stars and many galaxies. He held the Dob in place on the current
object while I scribbled notes and looked up the hop to the next galaxy. What a
riot we had that night. Bagged thirty new galaxies. Once we got lost and had to
start all over from the beginning again. But that was all part of the fun. Later
at home when updating my log book from my notes, I colored in the galaxies we'd
found with a red pencil crayon on the “cut and pasted” chart I'd made.
That was the start of a
great galaxy hunt and a new tradition. When I did get my copy of Uranometria
(first edition) I continued coloring in the objects I'd visited. Red for
galaxies, green for nebulae, yellow for open clusters, orange for globulars and
gray for dark nebulae. Within three years I had a moderately colorful
Uranometria with over 450 objects colored. I hope I'm more than just a hunter -
gatherer. I am enjoying the view and revelling in the many objects unique
characteristics. I'm often reminded of the old joke: Did you hear? Vice
president ___ 's library burned down. Both books. And he hadn't finished
coloring in one of them. (That's me!)
Now with my moderately new
16.5 inch f 5.3 home built Newtonian, I have the new second edition of
Uranometria and I'm just hankering to get coloring galaxies. Due to technical
difficulties I've missed using the scope both of the last two Springs. My galaxy
pages in Virgo and Coma Berenices are mostly just black and white. But this time
I'm ready for the Galactic Rush Hour.
(About the author:
Darrell Abrahams is a member of the Fraser Valley Astronomers Society of British
Columbia, Canada, and is an avid deep sky observer. Why not go to:)
(About some of the
photos: Richard Crisp is a design engineer who works in Silicon Valley,
California, USA. Never satisfied with the detail level gained through the
telescope, he has turned to the camera. Through an ongoing, growing, and
thorough study of astrophotography and its techniques, with a scientist’s
knowledge of how light works, he seeks to engage objects he’s seen in space
photographically and frequently lectures on astro-imaging. He is also a
peripatetic equipment builder in the astrophotography field. NASA has used some
of his photos as the “Astronomy Picture of the Day.” We expect to see more
photos from him worked into NAR features, and perhaps his own column on
astro-imaging and equipment design/optimization. Visit his site and his friends
in the TAC - “The Astronomy Connection" - online at:)
http://www.narrowbandimaging.com/
Coordinates over 50○
N
Sun, Moon and
planets
Courtesy U.S. Naval
Observatory and Stardate Online
MICA is the Multiyear
Interactive Computer Almanac. With it you can obtain sidereal time to your
specific location for the Sun, Moon and planets. To use MICA Version 1.5
(available as test or download) you will need to know your latitude and
longitude. To find Greenwich Mean Time (which is also Universal Time[UT]) find
your local time zone and count forward - or backward -to the time as it would be
at Greenwich (in the UK). MICA uses Universal Time (UT) for all its
calculations. All you need do it add UT and your latitude and longitude and
press a button to get rising and setting times of various Solar System objects.
(See link below)
To calculate for planetary
and solar postions, see link below NAR guest feature
Artificial universe
: seeing ahead with the Scenario Machine
Vladimir
Mikhailovitch Lipunov
The Scenario Machine
Based on the present
notions of normal and relativistic star’s evolution in binary systems,
population synthesis of the universe can be carried out.
This artificially created
“Metagalaxy” contains, among well known and clearly understood astrophysical
processes and objects, phenomena not yet found, yet which is highly significant
for all modern science.
A specially constructed
computer program at the Moscow State University - the Scenario Machine - allows
predicting the number and main physical characteristics of relativistic binary
systems, the discovery of which in forthcoming years will lead to two
fundamental results:
* Gravitational waves’
detection
* Confirmation of the
existence of black holes
At the links listed below,
we show our code. At the present time it allows you to obtain evolutionary
tracks of the close binary system with different parameters, which you determine
yourself. Please read "How all this stuff works"
(http://xray.sai.msu.ru/~mystery/articles/review/ ) in order to get more
information about the code and its opportunities, and read "Credits" in order to
get some information about the demiurges of the code and its web version. (To
build your own track, follow "Go to evolutionary track constructor.")
Welcome to the WWW-world of
close binaries!
* Basic parameters
* Kick velocity
* Scenario branches
* Additional parameters
* Output parameters
For more on the
above-bulleted parameters, see
http://xray.sai.msu.ru/cgi-bin/scenario.4.0/main_form.4.0.5.cgi
“How all this stuff works”
In the early 1980s our
understanding of binary star evolution, based on the pioneer work of Paczynski
(1971), Tutukov and Yungelson (1973), van den Heuvel and Heise (1972) allowed us
to construct a general evolutionary scenario which successfully explained the
genesis of well-studied normal stars, and offered potential explanations for new
X-ray sources discovered in space experiments.
It was recognized then that
the evolution of binary systems looked like a branching genealogical, or
“family” tree whose nodes include important physical processes. These processes
are the mass exchange between binary components, the common envelope stage (or
“CE”), loss of orbital angular momentum at the expense of gravitational wave
emission, the magnetic stellar wind (and so on).
________________________________________________________________
Guest writer Dr. Lipunov with book and dog.
________________________________________________________________
________________________________________________________________
________________________________________________________________
To find
Moon phases for the month
http://www.stardate.org/nightsky/moon)
__________________________________________________________________________________________
Artist's impression of gravitational waves. (LIGO)
On the other hand, it was
clear that dramatic new processes should occur after a compact star White Dwarf
(WD), Neutron Star (NS) or Black Hole (BH) has been formed in a binary system.
Taking account of these processes was especially important in the cases of WD
and NS, as they can have strong magnetic fields and rotate rapidly. Here, we
come across a new phenomenon in stellar evolution - the evolution of gravitating
magnetic compact stars (gravimagnetic rotators). The original idea goes back to
pioneer work by V.F. Schwartzman (Schwartzman 1970a, 1971), Illarionov and
Sunyaev (1975), Bisnovatyi-Kogan and Komberg (1975), Shakura (1975),
Wickramasinghe and Whelan (1975), Lipunov and Shakura (1976), Savonije and van
den Heuvel (1977), and Lipunov (1982a) and means that astrophysical
manifestations of the magnetized compact star are mainly determined by its
interaction with the surrounding plasma by means of two types of physical
fields: electromagnetic and gravitational, and the evolution itself represents a
gradual change of the character of this interaction. The universality of such an
approach is not only its ability to explain apparently such different objects as
radio pulsars, X-ray pulsars, X-ray bursters, cataclysmic variables, polars,
transient X-ray sources, etc., but also its ability to predict completely new
and still undiscovered objects.
Therefore, the realistic
treatment of binary star evolution must include both types of evolution:
* The nuclear evolution for
the normal stars, and
* The rotational evolution
for the compact magnetized stars.
The last fact complicates
the evolutionary tree to such a point that the need for a special numerical tool
for studying binary evolution (the Scenario Machine), analysis of the observed
picture and approval of the evolutionary scenarios is clear (Kornilov and
Lipunov, 1983a, b). Now it consists of a large numerical code that incorporates
the crucial physical processes in binary systems and takes into account:
* Mass exchange between
binary components
* Loss of the orbital
momentum due to gravitational waves
* Loss of the orbital
momentum due to magnetic wind
* Evaporation of normal
stars by radio pulsars
* Spin evolution of
magnetic compact stars.
The history of the Scenario
Machine can be briefly summarized as follows:
* (a + e) Massive binaries
(M ≥ solar mass )
* (a + b + c + e) Low-mass
binaries (M < 10 solar mass)
* (a) Massive binaries
* (a + b + c + d + e) All
mass
* (a + b + c) All mass
* (a + b + c) Low-mass
binaries
Apart from giving an
explanation for the known evolutionary stages of binary systems, this code
proved to be a powerful tool for studying evolutionary links between different
binary star populations (Lipunov, 1994). The results obtained with the Scenario
Machine include the following:
* Prediction of nearly 100
new stages of binary systems with magnetized compact companions
* Prediction of millisecond
X-ray accreting pulsars
* Explanation of some of
the ultra-soft, super-luminous sources as super-accreting compact stars in
binaries, which was confirmed by the discovery of a transient X-ray pulsar RX
J0059.2-7138 in the Small Magellanic Cloud (SMC)
* Prediction and estimation
of the number of binary radio pulsars with OB-stars ( ~ 1 per 700 visible
galactic pulsars) which was confirmed by the discovery of PSR B1259-63
* Estimation of the number
of binary radio pulsars with black holes
* Calculation of the
gravitational wave background formed by galactic and extragalactic binaries.
Many important physical effects were shown to follow from the
modern evolutionary scenario, among which are those listed below.
* Anisotropy of supernova
explosions (that is, these explosions having differing physical properties in
different directions) giving “kick'' velocities of young pulsars of ≈ 70-100
km/s
* A significant evolution
of supernova rates and binary NS merging rates at cosmological distances
* A strong link between the
relative number of binary radio pulsars with different compact components and
star burst formation history.
In the future
The results of Scenario
Machine computations are aimed at the population synthesis of different types of
binary stars in the Galaxy, and in other galaxies. They demonstrate the ability
of this method to make an important gross analysis of the modern scenarios for
binary evolution, as well as to give interesting qualitative and quantitative
predictions which can be checked observationally.
Even the last version of
the code used in the Scenario Machine is rather a schematic representation of
the evolution of binary systems, which in reality is much more complicated.
However, even at the present level the method is obviously indispensable for
overall analysis of different evolutionary scenarios, and, hence, for
understanding binary stellar evolution as a whole. The future development of the
method can be considered from two different points of view.
First, this is the
amendment of the method itself in the sense of more adequate and detailed
description of stellar evolutionary tracks (as performed by, for example, Pols
and Marinus (1994). In fact, this is indeed necessary for some classes of
objects (for instance, if we investigate in detail a particular type of object,
such as cataclysmic variables, their distributions over masses, orbital periods,
etc.). However, here one should always bear in mind that various uncertainties
of the modern evolutionary scenario (such as adequate description of the common
envelope stage, Roche lobe overflow process, parameters of the magnetic stellar
wind, etc.) could hardly make the detailed calculations more precise than they
already are (that is, they do remain uncertain to within the same factor of 2).
On the other hand,
interesting results (which are more statistically reliable) can be obtained by
applying Scenario Machine methods to various examples of extragalactic binary
system’s evolution. That is, it may be better not to refer to the evolution of
stars, but to the evolution of the baryonic component of our Universe instead.
One important feature
revealed by our computations is that practically all populations of stars in
galaxies are very sensitive to the previous star formation history. In this
connection, a more accurate account of the relevant chemical evolution is
urgently needed, and this is what we are going to do in the near future.
(About the author: Vladimir
Mikhailovitch Lipunov is Soros Professor at Moscow State University and the
Sternberg Astronomical Institute and originated the idea of the Scenario
Machine, as well as coordinating the whole project. Also involved are: Mike
Prokhorov (Scenario Machine coding & adapting code to the web); Konstantin
Postnov (Scenario Machine coding ); Sergey Nazin (web interface design &
coding, project coordination); Ivan Panchenko (Scenario Machine coding &
Image generation); Sergei Popov (Scenario Machine coding). Parts of this article
were excerpted from the Introduction of “The Scenario Machine: Binary Population
Synthesis” (Harwood Academic Publishers)
http://xray.sai.msu.ru/~mystery/articles/review/ .)
Astronomical science
news from Science and Nature
Discovery
proves mass extinction due to asteroids: a connection to life
Matthew Huber of Purdue
University (USA) who has been studying geological biophysics for decades and has
found fossil evidence marking rapid global cooling 65 millions years ago. The
cooling occurred in the so-called “K-T boundary” (Cretaceous-Tertiary Periods)
when a massive asteroid struck Earth, believed to have caused large dinosaur
extinction. (Until now only geological proof was cited.)
A Tunisian site, El Kef,
contains layers the same age as those of Chicxulub Crater, where the mile wide
asteroid struck Earth near modern day Mexico. The evidence for it turned out to
be small, cold-loving ocean organisms called dinoflagellates and benthic
formanifera. These appeared suddenly in an ancient sea that had previously been
very warm at El Kef, right before the impact.
"The fossils indicate that
something suddenly made the water cold enough to support these tiny critters,"
Huber said. What probably caused the prolonged Earth climate-changing cold were
dust screens that blocked sunlight for years. Thus an “impact winter” occurred
when the asteroid punch forced massive quantities of Earth’s crust into the
upper atmosphere.
Huber said that life on the
Earth's surface was probably recovering about 30 years after the meteorite
impact. But the fossil record shows that cold-loving dinoflagellates were
present at El Kef for as long as 2,000 years afterwards. Long term cooling (a
thousand years, plus) from this time matches data in climate models.
"It took much longer for
the oceans to get back to normal," Huber said.
_____________________________________________________________________
This discovery certainly
has relevance to theories about dinosaur extinction. The findings can also help
experts understand recent climate change. It also sheds light as to what happens
to Earth’s climate after sizeable asteroid collisions. (ABC Science Online, June
2004; letter to Geology: June 2004, Vol. 32, No. 6, pp. 529-532.)
Simulations
seem to explain jets in black holes
Some scientists are
actually trying to describe aspects of black holes rather than just theorize
about them.
Vladimir Semenov of the
Institute of Physics at the University of St. Petersburg (Russia) admits that
the origins of jets emitted by black holes are poorly understood. Two possible
energy sources of these jets are accretion disks or the rotating black hole.
Simulations involving magnetohydrodynamics explain these jets in models. The
physics of the jet initiation is explained by a black hole gravitohydromagnetic
theory in their paper. (V. Semenov et al, Science, August 2004).
Relax...it's
the moon
_____________________________________________________________________
In astronomical
history...
The measure of
time using space: transit instruments and other beginnings of astrometrics
Steven H. Yaskell
“Transits, or transit
telescopes are part of a triplet of astrometric instruments that include transit
circles and meridian circles. They were used to measure time and meridian.”
(Encyclopedia Britannica)
With Johannes Kepler’s
Rudolphine Tables the most accurate measurements of the northern hemisphere’s
stars became available, the combined work of himself and the skilled naked eye
observer from Denmark, Tycho Brahe. With these tables the world of studied,
practical astronomy could be said to have begun.
What was most practical to
astronomy at the time were affairs of state, tied to needs for faster and better
navigation across seas. This was for the purpose of discovery, conquest, and
economic expansion driven by widening and forever warring European populations.
There were, for example, no practical, independent ship’s clocks until the late
18th Century. Sea captains and crews as late as this time coursed the world’s
oceans using eye-based celestial navigation. Tools such as sextants and
quadrants and rule of thumb memory guided the wits of ship’s pilots, and two of
these three required clear skies. Galileo devised a system of telling time
exactly at sea depending on the position of Jupiter’s moons. Yet this method,
too, required nifty seeing, not to mention the availability of Jupiter in the
sky. (And why not throw in a telescope for good measure?) Bad weather delayed
point-to-point shipping of goods, travellers, and soldiers. This negatively
effected markets and empires equally. Royal leaders were angry, as were their
commerce-hungry subjects.
A better set of star tables
was all well and fine, thanks to Kepler’s efforts. Right ascensions and
declinations of known stars sped the process of place identification and motion
across waters with these and the available navigating tools of the sailor. Yet
practical shipping needed constant improvement due mostly to not having any real
ship’s clocks to rely on. Transit measurement grew in importance while the world
sought a stable ship’s clock. The need for having instruments to determine
latitude, for instance, was such that the French king created the Paris
Observatory in 1667 (Pannakoek: 1962). If so, a slew of observatories with
similar agendas sprung up in England, Sweden, Russia, Denmark and elsewhere -
following in short order. Savants and scholars alike tackled problems of
measuring time with the help of space, from the aforementioned Galileo to the
pragmatic Frenchman, Jean Picard, and in particular, to Ole (or Olaus) Römer,
one of Picard’s men who would himself become a practical problem solver in his
native Denmark.
Römer edited his famous
countryman’s (Brahe’s) papers early on, perhaps in preparation to conceiving the
transit instrument. Arguably, Römer was the first to have the idea of attaching
a telescope to a meridian transit instrument (Westfall: 2004). Picard became the
Dane’s patron in Paris, inviting him to the French academy and to the
observatory where Römer learned how to observe like the remarkable Frenchman.
There should be little doubt that Picard’s instrument making informed the Dane’s
own thinking.
The device was a telescope
mounted at right angles affixed to a horizontal axis. It faced east-west. When
the axis was moved in the revolving motion, the line through the telescopic
sight traced out the meridian. As he had improved the micrometer (see autumn
2004 edition, NAR) Römer similarly simplified measuring celestial angles, as it
could be well thought that the Paris Observatory employed dozens to move about
various equipment while performing different tasks requiring precision.
Simplification was due.
As better land clocks made
their appearance in this century so marked by the importance of time, Römer’s
improvements of the transit process included land clocks. His common focus in
the eyepiece was a web of horizontal and vertical wires, all of which were
illuminated by a lamp, lens and reflector, a beam of candlelight flashing on the
wires from a hole in the telescope’s side. As clocks ticked out seconds Römer
could observe the wires move as the circle moved with his twisting the
instrument, as any would turn the worm-screw of a German telescopic mount. So
the time of transit across the meridian could thus be calculated. The
illumination probably helped keep the light sky (blue or cloudy) from
interfering with the daylight measurement process.
Errors were found in the
measurements and rounded off, time of clock tick versus instrument movement.
Differences in right ascension could be found. The declinations corresponding to
these were read off through a microscope. The microscope was carried round by an
index perpendicular to the axis of the instrument (probably that marked “E” in
the woodcut in Wolf, above). It travelled over a graduated circle.
As all his instruments and
records of observations vanished in a fire in 1728, we may never know exactly
how Römer made and used his instruments.
Meridian measurement hits
high gear
Countries sought to align
themselves with the rest of the world geographically, from the shifting of the
prime meridian to going onto standard time (for example, Sweden, in 1879).
Observatories performed more standard functions related to time keeping and
travel rather than deep space study alone, and sought a global reach. Modern
markets had forced this standardization and the accurate ship’s clock helped
markets grow. In Sweden's case the issue of the meridian was solved by going
international, when Stockholm and Gothenburg could not decide on the location,
accepting the compromise of a mid-point between these two cities. In 1900, the
observatory started to follow Greenwich Mean Time – something not all nations
were willing to do, as the British Empire’s might and worldwide reach had more
to do with making it the beacon of world commerce and hence, universal time
setting, whether here on Earth, or in space. In any case, a universal measure
was needed for this, somewhere, and Sweden and other nations fell in step with
Britain.
To put all this into
perspective, however, requires contemplating Römer’s pioneering work and a quick
study of some German instrument makers and astronomers who fine-tuned the
processes. Georg von Reichenbach introduced the meridian, or transit, circle in
the late 1700s. With it one could measure both the time when a celestial body is
directly over the meridian (the longitude of the instrument) and the angle of
the body at meridian passage. Reichenbach’s instrument making took on industrial
process proportions in Munich, giving the astronomer Friedrich Wilhelm Bessel
the chance to determine accurately positions of 9th magnitude stars from +15
declination, eventually to +45 (Pannekoek: 1962). Using a Reichenbach meridian
circle over a period of 13 years, Bessel accumulated an atlas of over 75,000
stars in exact positions. Given that Bessel was the first man to accurately
determine parallax, there is no need to boast of the accuracy he and his
assistant Argelanger achieved in the Bonner Durchmusterung and other maps. That
he greatly improved Kepler and Brahe’s work is understatement.
With Bessel and others, astrometrics could be construed as having arrived on the scene in modern mathematical science. Astrometry lies out, as one definition has it, “the inertial system of space coordinates and a coordinated scheme of fundamental astronomical constants, realizing the connection of this system with Earth, on the basis of the receipt of coordinates of celestial objects and the study of the rotational irregularities of Earth.” It is a measured base for practical astronomy and geodesy, geophysics, and geology. Practical architecture and the construction trades are linked to it as much as today’s space travel. The theodolite was invented by Reichenbach, by the way: every land surveyor’s key tool.
Once again, there was a shift in emphasis as to what these instruments were used for. By the early 1800s, reliable ship’s clocks of the Harrison type were aboard all ocean going vessels. And even if map coordinates, time, and other functions were still being determined locally in nations across the world, standardization was creeping in. In the timeframe of 1800-1900, other brands of transit “telescope” and meridian had their birth, such as the Megele, Bamberg, and the Salmoiraghi and Ertel. Error correction was ever more refined, as well as determining star positions more accurately.
The instruments were used
to aim the largest telescopes in the world and many large telescopes saw their
birth toward the end of the 19th Century. Did the importance of what transits
did shift back to “big astronomy?”
Transit circles indeed had
collimation uses. Like every other country, the United States installed a
transit circle (the 6-inch transit circle at the United States Naval
Observatory) built in 1898 by Warner & Swasey. It went out of service in
1995. They were used to assist the infant satellite and space exploration
programs of the 1950s and 1960s, as it had earlier aided Earth bound telescopes.
But now their use has diminished to a mere whisper from its former roar.
Transit Circle telescopes
are being replaced by newer instruments capable of determining stellar positions
to an accuracy of 0.01 arcseconds, up from the 0.05 arcseconds the Warner &
Swasey transit could obtain. This is interferometer technology such as the Very
Long Baseline Interferometer (VLBI) array of radio telescopes measuring the
precise positions of distant quasars, and optical interferometers. Precise
positions of distant quasars, probably the furthest thing at a distance so
measurable, are now gathered. Such a framework formed by these distant objects,
back measured towards our Earth, allow tiny oscillations of Earth’s rotational
poles to be measured.
The worlds of Römer and
Bessel recede more deeply into history. We now plumb the depths of space to such
an extent that space mapping for the purposes of Solar System navigation and
telescope aiming will be more exact, common and seamless than ever before.
Sources
Römer, Picard: Compiled by
Richard S. Westfall from original Danish and French sources (Department of
History and Philosophy of Science, Indiana University – Internet, 2004); A
History of Science and Technology in the 16th and 17th Centuries, Vol. 1, by A.
Wolf (George Allen & Unwin LTD: 1962)
Kepler, Brahe: Casper, M.,
Kepler (Dover: 1993); Moore, P., Watchers of the Stars (Michael Joseph : 1973)
Picard, Bessel, Argelander,
Reichenbach: Interview with Inga Elmqvist (curator) Gamla Observatoriet (Kungl.
Vetenskapsakademien) June, 2002 by the author; Lindroth, S., Kungl. Svenska
Vetenskapsakademiens historia (1739-1818) (Stockholm: 1967) pp 398-411;
Pannakoek, A., A History of Astronomy (Dover : 1989) and various Internet
sources.
Other: United States Naval
Observatory website, Sobel, D., Longitude (Fourth Estate: 1995)
Equipment review...
Sovietski 6" f/8 Reflector
3/10/00 (6" f/8 equatorial Newtonian, AC RA drive, 42 mm, 25 mm, 15 mm, 4X
barlow $649 + $75 shipping) (Now sold by Talscopes as TAL-2)
By Ed Ting
I am just old enough to
remember when being an "amateur astronomer" meant that you owned a 6" reflector.
Twenty or thirty years ago, it was all you could get - a far cry from today.
Nowadays, it seems like nobody makes them anymore.
Imported from Russia by
Mitch Siegler, Sovietski sells Russian optical equipment, along with lots of
other pieces of Russian memorabilia (ask for their catalog.) I remember my first
encounter with a Sovietski telescope at a star party. Two things stuck me:
First, the scope produced some really nice images, and secondly, it seemed to
take the owner forever to set it up.
And so it was that I found
myself going through those same experiences. This telescope was supplied as a
review sample from Sovietski. The scope arrived in two huge -and I do mean huge-
shipping containers. I found myself pondering how it was possible for a scope
weighing 68 lbs to have a shipping weight of 166 lbs. Yes, the containers for
this 6" scope weigh MORE than the 20" Obsession they were sitting next to.
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You get a lot for your
$650. The tube and most of the mount come neatly packed away in a massive 91 lb
dovetailed pine box resembling a coffin. The equatorial head comes in a second,
smaller pine box. The designers of this telescope must have lived by the motto
"A place for everything, and everything in its place" because there seems to be
a little alcove, or wooden holder for each part of the scope. In fact, I had
some difficulty remembering where everything went when it came time to repack
and return the scope.
As I hinted above, it takes
a while to put all this stuff together. However, unpacking and assembling a
telescope for the first time ranks as one of Life's Great Pleasures, and I
didn't mind. The parts of the scope are large, beefy, and heavy. Some parts,
like the threads on certain bolts, come conveniently lubricated. Unfortunately,
other parts, like the declination shaft and most of the finder bracket, are not
only lubricated, they arrived positively slathered in grease. I had to run
inside a number of times during assembly to wash my hands.
Once assembled, I moved the
scope outdoors on a cool, crisp night. The scope is nicely finished, and is in
sharp contrast to the military-looking cosmetics on most other scopes from the
former Soviet Union. The scope is -dare I say it- even attractive, something I
never thought I'd say about a Russian telescope. This Sovietski is the first
Russian scope I've ever seen that didn't look as if it were getting ready to
shoot something.
The primary is spherical.
Despite this, it shows really nice images. I did a mini Messier tour through the
winter sky and hit the Virgo Cluster. The scope's images were clear and
contrasty. The 8X50 finder is wonderfully sharp, almost to the edge. In an age
when most of the major manufacturers are trying to put the cheapest possible
finders on their scopes, this was refreshing. Of the eyepieces, I liked the 25
mm Plossl the best. The supplied 4X barlow is also of good quality. The 42 mm
Kellner had a too- narrow FOV, and the 15 mm Kellner was too tight on eye
relief.
A spherical mirror is an
undercorrected mirror, and this showed up in the star test at 150X, which
revealed about 1/4 wave of spherical aberration. I didn't notice much, if any,
degradation of the image because of this.
It wouldn't be a true
Russian telescope without a few quirks, so here they are. You practically have
to disassemble everything to put the pieces back into those pine boxes. The
drive is AC only. There is no lens cap for the finderscope. The rings look like
they will fit on any mount, but they won't - they're keyed to the plate on the
supplied mount. The mount's controls are a little clunky. Finally, the
instructions are like a long Russian winter: grey, and a little dreary.
I enjoyed my time with this
telescope. Although it's only 11 lbs heavier than the Meade Starfinder, it feels
far more substantial and solid. The Meade, in fact, feels positively dainty next
to this Sovietski, with its plastic focuser and finder, paper tube, etc. But the
Meade costs a lot less, at $499. So take your choice, as they're both
recommended.
In a time of Goto-this and
Apochromatic-that, is was nice to spend a few nights enjoying a simple,
traditional 6" f/8 Newtonian. I can tell you that I seriously considered buying
the review sample, but in the end I could not justify yet another telescope in
the garage. It went back to Sovietski without me.
(About the author: Ed Ting
has been reviewing right-off-the-assembly line telescopes and related equipment
for years in magazines such as Sky & Telescope and many others. He lives in
Connecticut, USA.)
Holy Spring
Dylan Thomas
O
Out of a bed of love,
When that immortal hospital
made one more move to soothe
The cureless counted body,
And ruin and his causes
Over the bed and shooting
sea assumed an army
And swept into our wounds
and houses,
I climb to greet the war in
which I have no heart but only
That one dark I owe my
light,
Call our confessor and
wiser mirror but there is none
To glow after the god
stoning night
And I am struck as lonely
as a holy maker by the sun. No
Praise that the spring time
is all
Gabriel and radiant
shrubbery as the morning grows joyful
Out of the woebegone pyre
And the multitude’s sultry
tear turns cool on the weeping wall,
My arising prodigal
Sun the father his quiver
full of the infants of pure fire,
But blessed be hail and
upheaval
That uncalm still it is
sure alone to stand and sing
Alone in the husk of man’s
home
And the mother and toppling
house of the holy spring
If only for a last time.
(About the author: Dylan
Thomas [1914-1953] Welsh poet, writer, playwright and popularizer of the
performed “poetry reading” died under mysterious circumstances due to chemical
imbalances and drug and alcohol abuse at 39. He believed word sound nearly
obviated their meanings and gained quite a following, though damned for his
highly emotional engaging of intellectual audiences in Europe and abroad [he was
ten years ahead of his time]. Disturbed, he would have received medical
treatment today for depression. Battling poverty all his life -another cause for
depression in a high strung soul- near the end he received contracts for
thousands of dollars per week to read in the United States. But by that time his
mental condition hardly allowed him to notice. Lyrical, intense and expressing a
Celtic love of words, nature, imagery and God probably unparalleled in the
language, and disdaining “intellectual poets” [such as Eliot and Auden] he was
the favorite of a fellow Welshman, the actor Richard Burton, whose life
strangely paralleled his favorite poet’s.)
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