***********************************
The SOCIETY for POPULAR ASTRONOMY
***********************************
====================================================
Electronic News Bulletin No. 280 2010 January 17
====================================================
Here is the latest round-up of news from the Society for Popular
Astronomy. The SPA is Britain's liveliest astronomical society, with
members all over the world. We accept subscription payments online
at our secure site and can take credit and debit cards. You can join
or renew via a secure server or just see how much we have to offer by
visiting http://www.popastro.com/
QUADRANTIDS 2010 - FIRST IMPRESSIONS
By Alastair McBeath, SPA Meteor Section Director
Initial reports arriving from various parts of the UK so far have
suggested that even where people had clearer skies on January 3-4,
very sensibly scarcely any observers were prepared to chance the
often deadly icy conditions underfoot to get to their observing sites,
particularly when coupled with the glare from the moonlit snow.
However, there were a couple of casual fireball sightings, one each on
January 2-3 and 3-4, the second of which at least may have been a
Quadrantid, though a preliminary review of his video data by Enrico
Stomeo in Italy found just one fireball on January 2-3 or 3-4, a
magnitude -9 sporadic at 02:08 UT on January 4. Enrico's results, plus
more video data from Bob Lunsford in California, USA (all kindly
forwarded by Rich Taibi in Maryland, unable to watch himself because
of still more devastatingly cold temperatures than those in Britain, and
very high windchill), suggested healthy Quadrantid activity on January
3 at least. Visually, including details helpfully submitted by North
American Meteor Network leader Mark Davis (NAMN; see
http://www.namnmeteors.org ), Quadrantid results have arrived from
Tibor Csorgei (Slovakia; NAMN), David Scanlan (England) and David
Swann (Texas, USA; NAMN). These suggested Zenithal Hourly Rates
(ZHRs) may have been around 80 +/- 30 from ~17:30-20:15 UT on
January 3-4, though the very low radiant from Europe then made it
difficult to assess the reliability of this finding, especially in the absence
of the International Meteor Organization's (IMO's) usual "live" shower
webpage for the Quadrantids this year.
Some radio-meteor notes posted on the IMO-News e-mailing list on
January 5 by Japanese observer-analyst Hiroshi Ogawa indicated he
had found a peak around 16:00-18:00 UT on January 3. However, his
analysis method has proven somewhat controversial previously, as it
is unclear how the various disparate radio data have been combined
into a single numerical value, plus there have been occasions before
when insufficient allowance had been made for the varying sensitivities
of the different radio systems involved, as shower radiant elevations
changed with time. Of the radio observers reporting directly to us at
present, also including Assistant Meteor Director David Entwistle, only
Jeff Brower in British Columbia, Canada, was able to provide
detailed radio-echo counts across the expected Quadrantid maximum,
while the radiant was at a useful elevation. These seemed to favour a
peak around 12h-15h UT on January 3 instead, but also gave an
interestingly healthy response around 18:00-19:00 UT then as well.
Which was the true peak will likely only become clearer (if indeed that
can be achieved), once all the January radio results are in, hopefully
by mid February, plus any more visual or video data. See ENB 279
( http://snipurl.com/u3plp ) for the Quadrantid maximum predictions.
Some further notes, plus a graph of David's radio observations, are
available on the SPA's Observing Forum at: http://snipurl.com/u3plw .
If anyone else has Quadrantid meteor data to submit, please send
them along as soon as possible!
LANTERNS CAUSE "NEW YEAR METEOR SHOWER" ALERT
By Alastair McBeath, SPA Meteor Section Director
An unexpectedly large number of reports of "fireballs" or a "meteor
shower" from New Year's night, beginning in the early evening of
December 31, and running through till about 00:30 UT on January 1,
arrived from many parts of the UK. After carefully examining all the
information submitted, including follow-up notes from some of the
witnesses in the vaguer cases, no definite meteor observations were
found among them at all, only single or multiple "sky lantern" releases.
This came at the end of another general surge in reports of lanterns
mistaken for fireballs, beginning in mid-December. News was also
received of lifeboats being launched, and other emergency services
wasting time and effort, chasing nonexistent distress flares caused by
some of the lanterns in December, especially near coastal districts. We
last discussed sky lanterns in ENB 270 ( http://snipurl.com/u3qor )
during the summertime plague of them, with advice on separating them
from meteors and other moving lights in the night sky. Some progress
is being made in terms of improved public education regarding them.
For instance, one first-time witness who spotted a lantern in late
December, and reported it thinking it might have been a fireball, wrote
back to say they had realised it could not have been, after observing
more identical objects - lanterns - at New Year. On the other hand, a
few of the reported New Year objects were seen under cloudy skies,
so clearly could not have been meteoric at all. A lantern or two
continued to be reported from the first couple of days of January, but
hopefully this latest deluge of the things has now passed, barring the
odd one, at least till the next holidays. SPA Secretary Guy Fennimore
has already warned on the Forum that Chinese New Year is on
February 14, also St Valentine's Day...
URSIDS 2009
By Alastair McBeath, SPA Meteor Section Director
As noted on December's monthly meteor webpage, the largely
moonless Ursid maximum was scheduled to fall between 13:30-
16:00 UT on December 22 (the time the Earth passed closest to the
node of the stream's parent comet, 8P/Tuttle), perhaps with another
peak around 07:14 UT. ZHRs were expected to be 10-15 or so. With
neither timing favouring Britain, and December's weather being
remarkably poor, it is unsurprising no visual results arrived from here,
and the sole visual Ursid data came from NAMN watcher Tibor Csorgei
in Slovakia. However, Radio Meteor Observation Bulletin 197 for
December 2009 (RMOB; see http://www.rmob.org ) having recently
been provided by the kind offices of editor Chris Steyaert, a detailed
analysis of the shower's radio-behaviour has been possible. The list
of RMOB observers active in December included:
Enric Algeciras (Spain), Orlando Benitez (Canary Islands), Michael
Boschat (Nova Scotia, Canada), Jeff Brower (British Columbia,
Canada), Willy Camps (Belgium), Johan Coussens (Belgium),
Gaspard De Wilde (Belgium), David Entwistle (England), Karl-Heinz
Gansel (Germany), Mike Otte (Illinois, USA), Steve Roush (Arizona,
USA), Wayne Sanders (British Columbia, Canada), Andy Smith
(England), Chris Steyaert (Belgium), Dave Swan (England), Istvan
Tepliczky (Hungary), Dirk Van Hessche (Belgium), Maarten
Vanleenhove (Belgium), Felix Verbelen (Belgium), John Wardle
(England).
Radio-detectable Ursid activity was found primarily just on December
22, but without an especially clear or strong radio signature from the
shower, perhaps indicative of the anticipated fairly normal ZHRs. There
appeared to have been a more active period from about 02h-12h UT
then, with a likely core from ~05h-09h UT (this was difficult to confirm
exactly, because it coincided with the diurnal sporadic peak for Europe,
which usually occurs for a couple of hours either side of 06h each day).
Despite this, there was evidence for a brighter-meteor peak in the
07:00-08:00 UT data-bin from both Europe and North America, judging
by the increased numbers of longer-duration meteor echoes then. As
there was no sign of anything unusual after midday UT, this suggested
the 07:14 UT peak prediction was probably closer to reality than the
later nodal-crossing time. Graphs showing David Entwistle's radio
Ursid results can be found on the Observing Forum at:
http://snipurl.com/u3s4g .
GEMINIDS 2009 UPDATE
By Alastair McBeath, SPA Meteor Section Director
Little has changed in respect of the visual results discussed in ENB 279,
but some fresh data have arrived from Karl Antier (France), Pam Foster
(Scotland), Jonathan Shanklin (England) and William Watson (New
York, USA; NAMN), along with the majority of December's radio
observations in RMOB 197 (as noted, with the observers, in the Ursid
report above). The radio analysis found the Geminids produced
especially good activity from around 23h UT on December 12 through
to about 14h UT on December 14. Unfortunately, the peaks within this
general interval proved remarkably hard to pin-down beyond this, but
there were definite suggestions the overall better activity fell between
~00h-08h UT on the 14th, and seemed strongest from about 00h-05h
UT. However, it is difficult to be certain of this, because the activity also
showed another "peak" (if one less strong) around 04h-06h UT on
December 13. This interval on both dates was doubly awkward, as it
coincided with the European diurnal sporadic peak, and one of the
better North American radio-Geminid detection intervals. It was odd
these findings did not match especially well with the preliminary IMO
visual data, which suggested at least two main ZHR ~120-130 peaks
on December 14, near 19h-20h and 01h-02h UT, within a period of
enhanced activity, ZHRs ~100+, lasting from ~15:30 UT on December
13 to 20h UT on December 14. Given the strength of the visual activity
too, it was a little surprising to find quite a few of the radio datasets
showed a less-clear Geminid signature overall than might have been
expected from past results. Regrettably, why these seeming
discrepancies should have been present is not clear.
Despite this, a hearty "well done" goes to all our contributors from the
Geminid, Ursid and 2010 Quadrantid epochs, during a particularly
difficult winter for outdoor activities of any kind, let alone nocturnal
astronomical ones! We must hope conditions will be kinder as the new
year proceeds.
MARS IN JANUARY
By Andrew Robertson, SPA Planetary Section Director
I have just taken over as the Planetary Section Director. I will do a
profile of myself later, but in the meantime just want to remind
everyone that Mars is at opposition this month. If you look due East
late in the evening you can't fail to notice a bright orange/red
'star' outshining any other star (apart from Sirius) at magnitude
-1.1, although to me it seems at least as bright as Sirius owing to
atmospheric extinction because of Sirius's low altitude. Mars reaches
opposition on the 29th although it will be closest to the Earth on the
27th, when it reaches a diameter of only 14".1, less than at many
oppositions. It culminates at 1.30 am this weekend (16th/17th Jan) at
an altitude of 58 degrees from my Latitude of 52 degrees North,
although it is at a healthy 40 degrees by 10pm. It is currently 13".8
in diameter with a phase of 99%, so you will really need a power in
excess of x200 to start pulling out detail. For diehard all-night
observers or those who want to get up in the early hours Saturn rises
at 9.30 pm, culminating at 3.30 am at an altitude of 40 degrees. Its
rings are tilted towards us by just under 5 degrees so you will need
good seeing conditions to pick out Cassini's division.
KEPLER DISCOVERS FIVE NEW EXOPLANETS
Science Daily
The Kepler space telescope, intended to find Earth-size planets in the
`habitable zones' of Sun-like stars, was launched in 2009 March. It
continuously and simultaneously observes more than 150,000 stars, and
has already measured hundreds of possible planet signatures that are
being analyzed. Kepler looks for the signatures of planets by
measuring dips in the brightness of stars. When planets cross in
front of, or transit, their stars, they periodically block part of the
starlight. The size of the planet can be derived from the size of the
dip, and the temperature can be estimated from the characteristics of
the star it orbits and the planet's orbital period.
Now Kepler has discovered its first five new exo-planets, which have
been named Kepler 4b, 5b, 6b, 7b and 8b. [That begs the question why
the numbers did not start at 1!] The five planets are all much larger
than the Earth. Known as 'hot Jupiters', they range in size from
similar to Neptune to larger than Jupiter. They have orbital periods
ranging from 3.3 to 4.9 days. Estimated temperatures range from 1200
to 1600 degrees C. NOT very Earth-like! As the mission proceeds and
Kepler has time to gather more data, smaller and cooler planets should
be found. While many of the signatures detected so far are likely to
be caused by things other than planets, such as small stars orbiting
larger stars, ground-based observatories have confirmed the existence
of the five exo-planets. Kepler is expected to continue operations
until at least 2012 November.
INTERGALACTIC GAS STREAM LONGER THAN THOUGHT
NRAO
A stream of gas flowing from the Magellanic Clouds around our own
Milky Way is much longer and older than previously thought. The
Magellanic Clouds are the Milky Way's two nearest neighbour galaxies,
about 150,000 to 200,000 light-years away, and are deep in the
Southern Hemisphere; they are much smaller than our Galaxy and may
have been distorted by its gravity.
The first evidence of the gas stream, named the Magellanic Stream, was
discovered more than 30 years ago, and subsequent observations added
tantalizing suggestions that there was more. However, until now it
was not clear that all the gas was part of the same system. Now,
astronomers have used the Green Bank radio telescope to fill important
gaps in the picture of gas streaming outward from the Magellanic
Clouds. They combined their data with those from earlier studies with
other radio telescopes, including those at Arecibo in Puerto Rico,
Parkes in Australia, and Westerbork in the Netherlands. The result
shows that the stream is more than 40% longer than was previously
known with certainty.
One consequence of the added length of the gas stream is that it must
be older. Its age is now estimated at 2.5 billion years. The revised
size and age of the Magellanic Stream also provides a new possible
explanation for how the flow got started. The new age of the stream
puts its beginning near a time when the two Magellanic Clouds may have
passed close to each other, triggering massive bursts of star-
formation. The strong stellar winds and supernova explosions from
that burst of star-formation might have blown out the gas and started
it flowing toward the Milky Way. Earlier hypotheses for the stream's
cause required the Magellanic Clouds to pass much closer to the Milky
Way, but recent orbital simulations have cast doubt on such
mechanisms.
LESS ORDINARY MATTER THAN OTHERS SUPPOSED
University of Maryland
An international team of scientists has found that individual galactic
objects have less ordinary matter, relative to dark matter, than does
the Universe as a whole. Some scientists believe all ordinary matter,
the protons and neutrons that make up people, planets, stars, and all
that we can see, is a mere fraction (some say 17%) of the total
matter in the Universe. The protons & neutrons of ordinary matter are
referred to as baryons by devotees of particle physics and cosmology.
The remaining 83% is attributed to mysterious 'dark matter', the
existence of which is inferred largely from its gravitational pull on
visible matter. Dark matter is presumed to be some new form of
non-baryonic particle -- the stuff scientists hope the Large Hadron
Collider at CERN will create in high-energy collisions between
protons. The team posed the question of whether the 'universal' ratio
of baryonic matter to dark matter holds on the scales of individual
structures like galaxies. One might expect galaxies and clusters of
galaxies to be made of the same stuff as the Universe as a whole, so
if you were naive enough you might think that if you made an
accounting of the normal matter in each object, and its total mass,
you ought to get the same 17%.
However, the team suggests that individual objects have less ordinary
matter, relative to dark matter, than they would expect from the
cosmic mix, sometimes a lot less. Just how much less depends
systematically on scale, according to the researchers. The smaller an
object, the further its ratio of ordinary matter to dark matter is
from the cosmic mix. The research indicates that the largest bound
structures, rich clusters of galaxies, have 14% of ordinary baryonic
matter, close to the 17% they expect. In smaller objects --
individual galaxies and satellite galaxies -- the normal matter
content gets steadily less. In the smallest dwarf satellite galaxies,
the content of normal matter is only about 1% of what they think it
should be. The variation of the baryon content is very systematic
with scale, so they say. The smaller the galaxy, the smaller is its
ratio of normal matter to dark matter. To put it another way, the
smallest galaxies are very dark-matter-dominated.
ASTRONOMERS TRY TO EXPLAIN HUBBLE SEQUENCE
RAS
Not for the first time, some astronomers have been trying to explain
the diversity of galaxy shapes. They tracked the evolution of
galaxies over the thirteen billion years from the early Universe to
the present day. Galaxies make up most of the visible component of
the cosmos. The smallest have a few million and the largest as many
as a million million stars. American astronomer Edwin Hubble
developed in the 1930s a taxonomy for galaxies that has since become
known as the 'Hubble Sequence'. There are three basic shapes: spiral,
where arms of material wind out in a disc from a small central bulge,
barred spirals, where the arms wind out in a disc from a larger bar of
material, and elliptical, where the galaxy's stars are distributed
more evenly in a bulge without arms or disc. For comparison, the
galaxy we live in has between two and four hundred thousand million
stars and is classified as a barred spiral.
Explaining the Hubble Sequence is complex. The different types
clearly result from different evolutionary paths but at least until
now a detailed explanation has eluded scientists. The team combined
data from the infrared Two-Micron All-Sky Survey (2MASS) with their
computer model to reproduce the evolutionary history of the Universe.
To their surprise, their computations reproduced not only the
different galaxy shapes but also their relative numbers. The
astronomers' model is underpinned by and endorses the 'Lambda Cold
Dark Matter' model of the Universe. Here 'Lambda' is the highly
mysterious 'dark energy' component that some astronomers now like to
believe makes up about 72% of the cosmos, with cold dark matter
making up another 23%. [It's not our fault if even the assertions,
let alone the numbers, in different items in these Bulletins don't
chime with one another!] Galaxies are thought to be embedded in very
large haloes of dark matter, and researchers believe that those may be
crucial to their evolution. Their model suggests that the number of
mergers between the haloes and their galaxies drives the final outcome
-- elliptical galaxies result from multiple mergers whereas disc
galaxies have seen none at all. Our Milky Way galaxy's barred-spiral
shape suggests that it has had a complex history, with only a few
minor collisions and at least one episode where the inner disc
collapsed to form the large central bar. The goal now is to compare
the model predictions with observations of more distant galaxies.
HST OBSERVES VERY DISTANT GALAXIES
STSI
The Hubble space telescope has observed galaxies even more distant
than before and uncovered a primordial population of compact and
ultra-blue galaxies that have never been seen before. The data come
from images taken on the 'Ultra-deep Field' last August with the new
'Wide-Field Camera 3', which are deep enough at near-infrared
wavelengths to show galaxies at redshifts from z=7 to beyond z=8.
The clear detection of galaxies between z=7 and z=8.5 corresponds to
look-back times of approximately 12.9 to 13.1 billion years ago. The
images have been discussed by astronomers who say that the faintest
galaxies show signs of linkage to their origins from the first stars.
They are so blue that they must be extremely deficient in heavy
elements, thus representing a population that has nearly primordial
characteristics.
The existence of such galaxies pushes back the time when galaxies
began to form to before 500-600 million years after the Big Bang.
The deep observations also demonstrate the progressive build-up of
galaxies and provide further support for the hierarchical model of
galaxy assembly whereby small objects accrete mass, or merge, to form
bigger objects by a process of collision and agglomeration. The
galaxies are as small as 1/20th the Milky Way's diameter and are
crucial to understanding the evolutionary link between the birth of
the first stars and the formation of the first galaxies. Astronomers
also combined the new Hubble data with observations from the Spitzer
space telescope to estimate the ages and masses of the primordial
galaxies. Their masses seem to be only 1% of that of the Milky Way
and show that the galaxies, seen at 700 million years after the Big
Bang, must have started forming stars hundreds of millions of years
earlier, pushing back the time of the earliest star-formation in the
Universe.
Bulletin compiled by Clive Down
(c) 2010 the Society for Popular Astronomy
--
Good Clear Skies
--
Astrocomet
--
Colin James Watling
--
Real Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
--
Web: http://lyra.freewebsites.com/
The SOCIETY for POPULAR ASTRONOMY
***********************************
====================================================
Electronic News Bulletin No. 280 2010 January 17
====================================================
Here is the latest round-up of news from the Society for Popular
Astronomy. The SPA is Britain's liveliest astronomical society, with
members all over the world. We accept subscription payments online
at our secure site and can take credit and debit cards. You can join
or renew via a secure server or just see how much we have to offer by
visiting http://www.popastro.com/
QUADRANTIDS 2010 - FIRST IMPRESSIONS
By Alastair McBeath, SPA Meteor Section Director
Initial reports arriving from various parts of the UK so far have
suggested that even where people had clearer skies on January 3-4,
very sensibly scarcely any observers were prepared to chance the
often deadly icy conditions underfoot to get to their observing sites,
particularly when coupled with the glare from the moonlit snow.
However, there were a couple of casual fireball sightings, one each on
January 2-3 and 3-4, the second of which at least may have been a
Quadrantid, though a preliminary review of his video data by Enrico
Stomeo in Italy found just one fireball on January 2-3 or 3-4, a
magnitude -9 sporadic at 02:08 UT on January 4. Enrico's results, plus
more video data from Bob Lunsford in California, USA (all kindly
forwarded by Rich Taibi in Maryland, unable to watch himself because
of still more devastatingly cold temperatures than those in Britain, and
very high windchill), suggested healthy Quadrantid activity on January
3 at least. Visually, including details helpfully submitted by North
American Meteor Network leader Mark Davis (NAMN; see
http://www.namnmeteors.org ), Quadrantid results have arrived from
Tibor Csorgei (Slovakia; NAMN), David Scanlan (England) and David
Swann (Texas, USA; NAMN). These suggested Zenithal Hourly Rates
(ZHRs) may have been around 80 +/- 30 from ~17:30-20:15 UT on
January 3-4, though the very low radiant from Europe then made it
difficult to assess the reliability of this finding, especially in the absence
of the International Meteor Organization's (IMO's) usual "live" shower
webpage for the Quadrantids this year.
Some radio-meteor notes posted on the IMO-News e-mailing list on
January 5 by Japanese observer-analyst Hiroshi Ogawa indicated he
had found a peak around 16:00-18:00 UT on January 3. However, his
analysis method has proven somewhat controversial previously, as it
is unclear how the various disparate radio data have been combined
into a single numerical value, plus there have been occasions before
when insufficient allowance had been made for the varying sensitivities
of the different radio systems involved, as shower radiant elevations
changed with time. Of the radio observers reporting directly to us at
present, also including Assistant Meteor Director David Entwistle, only
Jeff Brower in British Columbia, Canada, was able to provide
detailed radio-echo counts across the expected Quadrantid maximum,
while the radiant was at a useful elevation. These seemed to favour a
peak around 12h-15h UT on January 3 instead, but also gave an
interestingly healthy response around 18:00-19:00 UT then as well.
Which was the true peak will likely only become clearer (if indeed that
can be achieved), once all the January radio results are in, hopefully
by mid February, plus any more visual or video data. See ENB 279
( http://snipurl.com/u3plp ) for the Quadrantid maximum predictions.
Some further notes, plus a graph of David's radio observations, are
available on the SPA's Observing Forum at: http://snipurl.com/u3plw .
If anyone else has Quadrantid meteor data to submit, please send
them along as soon as possible!
LANTERNS CAUSE "NEW YEAR METEOR SHOWER" ALERT
By Alastair McBeath, SPA Meteor Section Director
An unexpectedly large number of reports of "fireballs" or a "meteor
shower" from New Year's night, beginning in the early evening of
December 31, and running through till about 00:30 UT on January 1,
arrived from many parts of the UK. After carefully examining all the
information submitted, including follow-up notes from some of the
witnesses in the vaguer cases, no definite meteor observations were
found among them at all, only single or multiple "sky lantern" releases.
This came at the end of another general surge in reports of lanterns
mistaken for fireballs, beginning in mid-December. News was also
received of lifeboats being launched, and other emergency services
wasting time and effort, chasing nonexistent distress flares caused by
some of the lanterns in December, especially near coastal districts. We
last discussed sky lanterns in ENB 270 ( http://snipurl.com/u3qor )
during the summertime plague of them, with advice on separating them
from meteors and other moving lights in the night sky. Some progress
is being made in terms of improved public education regarding them.
For instance, one first-time witness who spotted a lantern in late
December, and reported it thinking it might have been a fireball, wrote
back to say they had realised it could not have been, after observing
more identical objects - lanterns - at New Year. On the other hand, a
few of the reported New Year objects were seen under cloudy skies,
so clearly could not have been meteoric at all. A lantern or two
continued to be reported from the first couple of days of January, but
hopefully this latest deluge of the things has now passed, barring the
odd one, at least till the next holidays. SPA Secretary Guy Fennimore
has already warned on the Forum that Chinese New Year is on
February 14, also St Valentine's Day...
URSIDS 2009
By Alastair McBeath, SPA Meteor Section Director
As noted on December's monthly meteor webpage, the largely
moonless Ursid maximum was scheduled to fall between 13:30-
16:00 UT on December 22 (the time the Earth passed closest to the
node of the stream's parent comet, 8P/Tuttle), perhaps with another
peak around 07:14 UT. ZHRs were expected to be 10-15 or so. With
neither timing favouring Britain, and December's weather being
remarkably poor, it is unsurprising no visual results arrived from here,
and the sole visual Ursid data came from NAMN watcher Tibor Csorgei
in Slovakia. However, Radio Meteor Observation Bulletin 197 for
December 2009 (RMOB; see http://www.rmob.org ) having recently
been provided by the kind offices of editor Chris Steyaert, a detailed
analysis of the shower's radio-behaviour has been possible. The list
of RMOB observers active in December included:
Enric Algeciras (Spain), Orlando Benitez (Canary Islands), Michael
Boschat (Nova Scotia, Canada), Jeff Brower (British Columbia,
Canada), Willy Camps (Belgium), Johan Coussens (Belgium),
Gaspard De Wilde (Belgium), David Entwistle (England), Karl-Heinz
Gansel (Germany), Mike Otte (Illinois, USA), Steve Roush (Arizona,
USA), Wayne Sanders (British Columbia, Canada), Andy Smith
(England), Chris Steyaert (Belgium), Dave Swan (England), Istvan
Tepliczky (Hungary), Dirk Van Hessche (Belgium), Maarten
Vanleenhove (Belgium), Felix Verbelen (Belgium), John Wardle
(England).
Radio-detectable Ursid activity was found primarily just on December
22, but without an especially clear or strong radio signature from the
shower, perhaps indicative of the anticipated fairly normal ZHRs. There
appeared to have been a more active period from about 02h-12h UT
then, with a likely core from ~05h-09h UT (this was difficult to confirm
exactly, because it coincided with the diurnal sporadic peak for Europe,
which usually occurs for a couple of hours either side of 06h each day).
Despite this, there was evidence for a brighter-meteor peak in the
07:00-08:00 UT data-bin from both Europe and North America, judging
by the increased numbers of longer-duration meteor echoes then. As
there was no sign of anything unusual after midday UT, this suggested
the 07:14 UT peak prediction was probably closer to reality than the
later nodal-crossing time. Graphs showing David Entwistle's radio
Ursid results can be found on the Observing Forum at:
http://snipurl.com/u3s4g .
GEMINIDS 2009 UPDATE
By Alastair McBeath, SPA Meteor Section Director
Little has changed in respect of the visual results discussed in ENB 279,
but some fresh data have arrived from Karl Antier (France), Pam Foster
(Scotland), Jonathan Shanklin (England) and William Watson (New
York, USA; NAMN), along with the majority of December's radio
observations in RMOB 197 (as noted, with the observers, in the Ursid
report above). The radio analysis found the Geminids produced
especially good activity from around 23h UT on December 12 through
to about 14h UT on December 14. Unfortunately, the peaks within this
general interval proved remarkably hard to pin-down beyond this, but
there were definite suggestions the overall better activity fell between
~00h-08h UT on the 14th, and seemed strongest from about 00h-05h
UT. However, it is difficult to be certain of this, because the activity also
showed another "peak" (if one less strong) around 04h-06h UT on
December 13. This interval on both dates was doubly awkward, as it
coincided with the European diurnal sporadic peak, and one of the
better North American radio-Geminid detection intervals. It was odd
these findings did not match especially well with the preliminary IMO
visual data, which suggested at least two main ZHR ~120-130 peaks
on December 14, near 19h-20h and 01h-02h UT, within a period of
enhanced activity, ZHRs ~100+, lasting from ~15:30 UT on December
13 to 20h UT on December 14. Given the strength of the visual activity
too, it was a little surprising to find quite a few of the radio datasets
showed a less-clear Geminid signature overall than might have been
expected from past results. Regrettably, why these seeming
discrepancies should have been present is not clear.
Despite this, a hearty "well done" goes to all our contributors from the
Geminid, Ursid and 2010 Quadrantid epochs, during a particularly
difficult winter for outdoor activities of any kind, let alone nocturnal
astronomical ones! We must hope conditions will be kinder as the new
year proceeds.
MARS IN JANUARY
By Andrew Robertson, SPA Planetary Section Director
I have just taken over as the Planetary Section Director. I will do a
profile of myself later, but in the meantime just want to remind
everyone that Mars is at opposition this month. If you look due East
late in the evening you can't fail to notice a bright orange/red
'star' outshining any other star (apart from Sirius) at magnitude
-1.1, although to me it seems at least as bright as Sirius owing to
atmospheric extinction because of Sirius's low altitude. Mars reaches
opposition on the 29th although it will be closest to the Earth on the
27th, when it reaches a diameter of only 14".1, less than at many
oppositions. It culminates at 1.30 am this weekend (16th/17th Jan) at
an altitude of 58 degrees from my Latitude of 52 degrees North,
although it is at a healthy 40 degrees by 10pm. It is currently 13".8
in diameter with a phase of 99%, so you will really need a power in
excess of x200 to start pulling out detail. For diehard all-night
observers or those who want to get up in the early hours Saturn rises
at 9.30 pm, culminating at 3.30 am at an altitude of 40 degrees. Its
rings are tilted towards us by just under 5 degrees so you will need
good seeing conditions to pick out Cassini's division.
KEPLER DISCOVERS FIVE NEW EXOPLANETS
Science Daily
The Kepler space telescope, intended to find Earth-size planets in the
`habitable zones' of Sun-like stars, was launched in 2009 March. It
continuously and simultaneously observes more than 150,000 stars, and
has already measured hundreds of possible planet signatures that are
being analyzed. Kepler looks for the signatures of planets by
measuring dips in the brightness of stars. When planets cross in
front of, or transit, their stars, they periodically block part of the
starlight. The size of the planet can be derived from the size of the
dip, and the temperature can be estimated from the characteristics of
the star it orbits and the planet's orbital period.
Now Kepler has discovered its first five new exo-planets, which have
been named Kepler 4b, 5b, 6b, 7b and 8b. [That begs the question why
the numbers did not start at 1!] The five planets are all much larger
than the Earth. Known as 'hot Jupiters', they range in size from
similar to Neptune to larger than Jupiter. They have orbital periods
ranging from 3.3 to 4.9 days. Estimated temperatures range from 1200
to 1600 degrees C. NOT very Earth-like! As the mission proceeds and
Kepler has time to gather more data, smaller and cooler planets should
be found. While many of the signatures detected so far are likely to
be caused by things other than planets, such as small stars orbiting
larger stars, ground-based observatories have confirmed the existence
of the five exo-planets. Kepler is expected to continue operations
until at least 2012 November.
INTERGALACTIC GAS STREAM LONGER THAN THOUGHT
NRAO
A stream of gas flowing from the Magellanic Clouds around our own
Milky Way is much longer and older than previously thought. The
Magellanic Clouds are the Milky Way's two nearest neighbour galaxies,
about 150,000 to 200,000 light-years away, and are deep in the
Southern Hemisphere; they are much smaller than our Galaxy and may
have been distorted by its gravity.
The first evidence of the gas stream, named the Magellanic Stream, was
discovered more than 30 years ago, and subsequent observations added
tantalizing suggestions that there was more. However, until now it
was not clear that all the gas was part of the same system. Now,
astronomers have used the Green Bank radio telescope to fill important
gaps in the picture of gas streaming outward from the Magellanic
Clouds. They combined their data with those from earlier studies with
other radio telescopes, including those at Arecibo in Puerto Rico,
Parkes in Australia, and Westerbork in the Netherlands. The result
shows that the stream is more than 40% longer than was previously
known with certainty.
One consequence of the added length of the gas stream is that it must
be older. Its age is now estimated at 2.5 billion years. The revised
size and age of the Magellanic Stream also provides a new possible
explanation for how the flow got started. The new age of the stream
puts its beginning near a time when the two Magellanic Clouds may have
passed close to each other, triggering massive bursts of star-
formation. The strong stellar winds and supernova explosions from
that burst of star-formation might have blown out the gas and started
it flowing toward the Milky Way. Earlier hypotheses for the stream's
cause required the Magellanic Clouds to pass much closer to the Milky
Way, but recent orbital simulations have cast doubt on such
mechanisms.
LESS ORDINARY MATTER THAN OTHERS SUPPOSED
University of Maryland
An international team of scientists has found that individual galactic
objects have less ordinary matter, relative to dark matter, than does
the Universe as a whole. Some scientists believe all ordinary matter,
the protons and neutrons that make up people, planets, stars, and all
that we can see, is a mere fraction (some say 17%) of the total
matter in the Universe. The protons & neutrons of ordinary matter are
referred to as baryons by devotees of particle physics and cosmology.
The remaining 83% is attributed to mysterious 'dark matter', the
existence of which is inferred largely from its gravitational pull on
visible matter. Dark matter is presumed to be some new form of
non-baryonic particle -- the stuff scientists hope the Large Hadron
Collider at CERN will create in high-energy collisions between
protons. The team posed the question of whether the 'universal' ratio
of baryonic matter to dark matter holds on the scales of individual
structures like galaxies. One might expect galaxies and clusters of
galaxies to be made of the same stuff as the Universe as a whole, so
if you were naive enough you might think that if you made an
accounting of the normal matter in each object, and its total mass,
you ought to get the same 17%.
However, the team suggests that individual objects have less ordinary
matter, relative to dark matter, than they would expect from the
cosmic mix, sometimes a lot less. Just how much less depends
systematically on scale, according to the researchers. The smaller an
object, the further its ratio of ordinary matter to dark matter is
from the cosmic mix. The research indicates that the largest bound
structures, rich clusters of galaxies, have 14% of ordinary baryonic
matter, close to the 17% they expect. In smaller objects --
individual galaxies and satellite galaxies -- the normal matter
content gets steadily less. In the smallest dwarf satellite galaxies,
the content of normal matter is only about 1% of what they think it
should be. The variation of the baryon content is very systematic
with scale, so they say. The smaller the galaxy, the smaller is its
ratio of normal matter to dark matter. To put it another way, the
smallest galaxies are very dark-matter-dominated.
ASTRONOMERS TRY TO EXPLAIN HUBBLE SEQUENCE
RAS
Not for the first time, some astronomers have been trying to explain
the diversity of galaxy shapes. They tracked the evolution of
galaxies over the thirteen billion years from the early Universe to
the present day. Galaxies make up most of the visible component of
the cosmos. The smallest have a few million and the largest as many
as a million million stars. American astronomer Edwin Hubble
developed in the 1930s a taxonomy for galaxies that has since become
known as the 'Hubble Sequence'. There are three basic shapes: spiral,
where arms of material wind out in a disc from a small central bulge,
barred spirals, where the arms wind out in a disc from a larger bar of
material, and elliptical, where the galaxy's stars are distributed
more evenly in a bulge without arms or disc. For comparison, the
galaxy we live in has between two and four hundred thousand million
stars and is classified as a barred spiral.
Explaining the Hubble Sequence is complex. The different types
clearly result from different evolutionary paths but at least until
now a detailed explanation has eluded scientists. The team combined
data from the infrared Two-Micron All-Sky Survey (2MASS) with their
computer model to reproduce the evolutionary history of the Universe.
To their surprise, their computations reproduced not only the
different galaxy shapes but also their relative numbers. The
astronomers' model is underpinned by and endorses the 'Lambda Cold
Dark Matter' model of the Universe. Here 'Lambda' is the highly
mysterious 'dark energy' component that some astronomers now like to
believe makes up about 72% of the cosmos, with cold dark matter
making up another 23%. [It's not our fault if even the assertions,
let alone the numbers, in different items in these Bulletins don't
chime with one another!] Galaxies are thought to be embedded in very
large haloes of dark matter, and researchers believe that those may be
crucial to their evolution. Their model suggests that the number of
mergers between the haloes and their galaxies drives the final outcome
-- elliptical galaxies result from multiple mergers whereas disc
galaxies have seen none at all. Our Milky Way galaxy's barred-spiral
shape suggests that it has had a complex history, with only a few
minor collisions and at least one episode where the inner disc
collapsed to form the large central bar. The goal now is to compare
the model predictions with observations of more distant galaxies.
HST OBSERVES VERY DISTANT GALAXIES
STSI
The Hubble space telescope has observed galaxies even more distant
than before and uncovered a primordial population of compact and
ultra-blue galaxies that have never been seen before. The data come
from images taken on the 'Ultra-deep Field' last August with the new
'Wide-Field Camera 3', which are deep enough at near-infrared
wavelengths to show galaxies at redshifts from z=7 to beyond z=8.
The clear detection of galaxies between z=7 and z=8.5 corresponds to
look-back times of approximately 12.9 to 13.1 billion years ago. The
images have been discussed by astronomers who say that the faintest
galaxies show signs of linkage to their origins from the first stars.
They are so blue that they must be extremely deficient in heavy
elements, thus representing a population that has nearly primordial
characteristics.
The existence of such galaxies pushes back the time when galaxies
began to form to before 500-600 million years after the Big Bang.
The deep observations also demonstrate the progressive build-up of
galaxies and provide further support for the hierarchical model of
galaxy assembly whereby small objects accrete mass, or merge, to form
bigger objects by a process of collision and agglomeration. The
galaxies are as small as 1/20th the Milky Way's diameter and are
crucial to understanding the evolutionary link between the birth of
the first stars and the formation of the first galaxies. Astronomers
also combined the new Hubble data with observations from the Spitzer
space telescope to estimate the ages and masses of the primordial
galaxies. Their masses seem to be only 1% of that of the Milky Way
and show that the galaxies, seen at 700 million years after the Big
Bang, must have started forming stars hundreds of millions of years
earlier, pushing back the time of the earliest star-formation in the
Universe.
Bulletin compiled by Clive Down
(c) 2010 the Society for Popular Astronomy
--
Good Clear Skies
--
Astrocomet
--
Colin James Watling
--
Real Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
--
Web: http://lyra.freewebsites.com/
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