SPA ENB No. 292

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                 The SOCIETY for POPULAR ASTRONOMY
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         Electronic News Bulletin No. 292      2010 July 18
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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/



JUNE BOÖTIDS - FURTHER DETAILS
By Alastair McBeath, SPA Meteor Section Director

It has remained unclear whether any significant June Boötid activity
occurred on June 23-24, as had been predicted in advance, further
to the preliminary discussion given last time. An examination of the
results reaching the Meteor Section directly, coupled with
observations reported on the IMO-News and Meteorobs e-mailing
lists, has suggested that Zenithal Hourly Rates (ZHRs) between
roughly 22h-06h UT on June 23-24 averaged 9 +/- 2, far below
the anticipated ~20-50. Video rates for the shower then averaged
about two sporadics per June Boötid, which while a rather crude
estimated method, did imply quite weak Boötid activity overall.
Radio results provided directly, plus those reported in June's Radio
Meteor Observation Bulletin (RMOB No. 203), showed little sign
of anything unusual on June 23-24, and nothing at all on June 27,
another potential date for June Boötid activity based on previous
years' events (see ENB 290, archived at: http://snipurl.com/zicst .
There was an indication of weak radio-meteor activity potentially
due to the Boötids between ~11h-13h UT on June 23 in some of
the data collected by observers in North America (European
observers had no suitable radiant elevation for the shower then).
Unfortunately, the relatively few sets of radio observations not
affected by summertime Sporadic-E interference (on which see
also ENB 290), and the paucity of data collected by other
techniques, made these results tentative only. It is though interesting
that none found the kind of easily-detected, sustained rates found
with the shower at both its other recent outbursts, in 2004 and 1998.

The observers whose data was used in preparing this analysis,
including those from the two e-mail lists, RMOB 203 (provided
by Editor Chris Steyaert; available at: http://www.rmob.org ),
and the North American Meteor Network (NAMN; see
http://www.namnmeteors.org ; results and additional discussion
from Network leader Mark Davis) were as follows, where "R"
means radio, "Vi" video and "V" visual results were provided by
that person:

Enric Algeciras (Spain; RMOB; R), Orlando Benitez (Canary
Islands; RMOB; R), Michael Boschat (Nova Scotia, Canada;
RMOB; R), Jeff Brower (British Columbia, Canada; R; some data
also in RMOB), Willy Camps (Belgium; RMOB; R), Johan
Coussens (Belgium; RMOB; R), Gaspard De Wilde (Belgium;
RMOB; R), Kurt Fisher (Utah, USA; RMOB; R), Karl-Heinz
Gansel (Germany; RMOB; R), Patrice Guérin (France; RMOB;
R), Javor Kac & colleagues (Slovenia; Vi + V), Paul Martsching
(Iowa, USA; NAMN; V), Mike Otte (Illinois, USA; RMOB; R),
Jürgen Rendtel (Germany; V), Steve Roush (Arizona, USA;
RMOB; R), Wayne Sanders (British Columbia, Canada; RMOB;
R), Andy Smith (England; RMOB; R), Chris Steyaert (Belgium;
RMOB; R), Enrico Stomeo (Italy; Vi), Dave Swan (England;
RMOB; R), Istvan Tepliczky (Hungary; RMOB; R + Vi), Michel
Vandeputte (Belgium; V), Felix Verbelen (Belgium; RMOB; R).

My grateful thanks go to all involved for their efforts, and also to
Rich Taibi in Maryland, USA, for additional discussions of some
of the early radio results especially. Any further June Boötid
observations would be very welcome still!


JUNE'S DAYTIME METEOR SHOWERS
By Alastair McBeath, SPA Meteor Section Director

Three major, annual showers have maxima due in June, all with
radiants near the Sun, and detectable from Britain only by radio in
the daytime. Details are given each year for them in our June
meteor activity webpage. In general, radio observers have managed
to follow something of them for many years, when summertime
interference has permitted. All three were discovered by radar from
Jodrell Bank in 1947. Theoretically, the Arietids should peak on
June 7, with past estimates implying their equivalent visual ZHRs
could be around 60. Similarly, the Zeta Perseids should reach
maximum on June 9 (visual-equivalent ZHRs ~40). Both these
radiants are so close together in the sky, and their maxima follow
one another so quickly, it is impossible for amateur radio-meteor
systems to separate the two. The final major daytime shower in
June is the Beta Taurids, with an often ill-defined peak around
June 28, best visual-equivalent ZHRs about 25. This is the Earth's
second annual encounter with the Taurid showers we see visually
overnight each year in the autumn. Drawing on extra data provided
by Jeff Brower in Canada, and the observers listed above from
RMOB 203, analyses were carried out to try to establish the more
likely near-maximum activities for all three sources.

A disappointingly large number of European radio datasets were
badly affected by Sporadic-E throughout the first half of June
especially, leading sometimes to entire days'-worth of results being
lost, a great frustration for both observers and analysts.
Consequently, the findings here are not as securely-established as
might be preferred. With that caveat in mind, a generally heightened
level of radio meteor activity was found in the majority of the
surviving results between June 6 and 12, due to daytime activity.
The most probable daylight peaks fell on June 8 and 11 within that
time, but neither was particularly obvious. These more probable
peak dates were in-line with the Section's analyses from previous
years, using results going back to the early 1990s, which have often
indicated the Arietid and Zeta Perseid peaks could be happening
around a day later than predictions suggested (which predictions
were based chiefly on radar results collected sporadically during the
late 1940s to early 1970s).

Gaps in the data created continued difficulties for the Beta Taurid
analysis, though a daylight peak can be inferred as falling between
June 24 and 28, likely due chiefly to this radiant or one nearby.
Within that period, a majority of the systems less-affected by
interference gave a probable peak on June 25 or 26. There were
also indications activity may have been rising again on June 30,
something which will need checking once all July's radio data is
available. As noted already, an ill-defined peak has seemed to be
a feature of the Beta Taurids, and previous examinations have
hinted that there may be more than one possible maximum date in
late June to early July.

Again, my most grateful thanks go to all the observers involved, with
commiserations to those whose data was badly-affected by Sporadic-E.


VERY SLOW FIREBALL IMAGED OVER FRANCE
By Alastair McBeath, SPA Meteor Section Director

An unusually long-lasting, very slow fireball that remained visible for
around 7-10 seconds, occurred over southern France on June 5-6,
at 22:37 UT. It was reported to the Section directly, but French
meteor and fireball analyst Karl Antier received a great many more
reports of it, including news that the event had been caught on video
by the Italian Video Meteor Network. The video record is available
at: http://snipurl.com/zivw5 .

Ordinarily, the SPA Meteor Section collects data chiefly on fireball
events spotted from the British Isles and places nearby, but any
British holidaymakers who were in France at the time and saw this
event are welcome to send-in a full report, if they have not already
provided details to Karl or the Section. Copies of such sightings
will be forwarded to Karl as well, to assist with his analysis. Details
on what to report, including an e-mail fireball report form, can be
found on the "Making and Reporting Fireball Observations"
webpage, at: http://snipurl.com/u8aer .


MAIN METEOR PROSPECTS FOR JULY-AUGUST
By Alastair McBeath, SPA Meteor Section Director

July-August brings one of the stronger near-ecliptic meteor
showers during the year, the Delta Aquarids, whose maximum
ZHRs of about 15-20 are usually achieved for a day or two around
July 28-30. Regrettably, the shower radiant's southerly Declination
(not unexpectedly, it lies near the star Delta Aquarii in late July),
means observed meteor numbers are always much lower than the
ZHRs from Britain, though rare Delta Aquarid meteors can be very
bright at times. Full Moon on July 26 ruins any possibility for
dark-sky coverage of the likely peak from the UK this summer,
though lower activity of these medium-speed meteors is usually
seen from circa July 12 till August 19. For more information and a
radiant chart, see July's meteor activity webpage at:
http://snipurl.com/zjivm .

By contrast, the Perseid maximum fares much better, thanks to new
Moon on August 10. It is due between 18:30 UT on August 12 to
07:00 UT on August 13 this year, most likely at some stage from
about 23:30 to 02:00 UT. It should produce ZHRs of around 100.
This most plausible peak interval is very favourable for Britain, as
the Perseid radiant, a few degrees northeast of the "Double Cluster"
near the maximum, can be usefully-observed from roughly 22h UT
onwards, culminating after dawn. Perseids are swift, often bright,
and commonly trained meteors, and those hoping to image some
may find their capture rates enhanced by aiming towards
And-Cas-Peg-Cyg. The shower is active from July 17 or so
through to August 24, and although rates are always lower away
from the peak, observed activity is usually good to very good for a
couple of days before the maximum plus a day or so afterwards.
This is important to remember if it seems the actual peak night may
be clouded-out. Further information and a Perseid radiant chart is
on the August meteor activity webpage, http://snipurl.com/zjjbd  .

Good luck, and clear skies!


PLANETS
By Andrew Robertson, SPA Planetary Section Director

I have had no reports of planetary observations since my last notice,
which is hardly surprising since it doesn't get reasonably dark until
after many people have gone to bed and there haven't been any planets
on prominent display.  You can see Venus low in the west after sunset,
and Mars & Saturn as it gets a bit darker, but they're all low down
and don't really offer much detail although they are still nice to see
with the unaided eye and binoculars.  On July 30, Mars and Saturn are
in conjunction less than 2 degrees apart, with the much brighter Venus
8 degrees away below and to the right.  Compared to Venus's brilliance
of mag -4.1 though, Saturn is only mag 1.1 and Mars 1.5.  By August 7
all three are within 3 or 4 degrees of each other but are only about 8
degrees above the horizon half an hour after sunset so still in a
brightish sky; they then effectively fade from view for this
apparition.

Jupiter, however, is coming to prominence, rising in the east in
the early hours.  I had a reasonable view of it. albeit low down
still. at 1am BST on July 15.  The NEB (north equatorial belt) is very
prominent and there is a trace of the 'vanished' SEB.  I am also
starting to see observations from other sources, what I would describe
as the die-hard amateurs who observe at every opportunity and produce
semi-professional results.  At 2am BST Jupiter will have risen to 22
degrees altitude on July 18, 28 degrees on July 31 and 33 degrees on
August 14.  Worth making an effort, as you can never know when that
SEB is going to make a dramatic re-appearance!

Uranus is not far from Jupiter throughout this next 4-week period,
just under 3 degrees to Jupiter's right (west).  At high power through
a telescope you can see a tiny greenish to slightly bluish disc and
during moments of good seeing you can see limb darkening which I
observed myself a few nights ago in the early hours.  Neptune comes to
opposition on August 20, but as it is low down in Capricornus and
presents a tiny blue disc about 2".5 in diameter there is not much
to be seen.

Any reports of observations would be most welcome via:
http://popastro.com/planet/contact/

I post a selection of members' observations on the SPA web site,
and they can be viewed on the Planetary Section's web page at:
http://popastro.com/planet/category/observations/


WAS VENUS ONCE A HABITABLE PLANET?
ESA

If Venus once had oceans, it might have been a habitable planet
similar to the Earth.  The Earth and Venus seem completely different
today: here, we have a lush, clement world teeming with life, while
Venus is hellish, its surface roasting at high temperatures.  But the
two planets are nearly identical in size, and now, thanks to the Venus
Express orbiter, planetary scientists are seeing other similarities.
One difference stands out: Venus has very little water.  Were
the contents of the Earth's oceans to be spread evenly across the
world, they would create a layer 3 kilometres deep.  If you could
condense the amount of water vapour in Venus' atmosphere onto its
surface, it would create a global puddle just 3 centimetres deep.

Yet, billions of years ago, Venus probably had more water.  Venus
Express has found that the planet has lost a large quantity of water
into space.  The loss occurs because ultraviolet radiation from the
Sun streams into Venus' atmosphere and breaks up the water molecules
into atoms, which then escape into space.  Venus Express has measured
the rate of escape and found that roughly twice as much hydrogen as
oxygen is escaping.  It is believed that water is the source of the
escaping ions.  It has also shown that deuterium, a heavy isotope of
hydrogen, is progressively enriched in the upper layers of Venus'
atmosphere because the heavier isotope does not escape so easily.

Everything points to there having been large amounts of water on Venus
in the past, but that does not necessarily mean that there were oceans
on the planet's surface.  A newly developed a computer model suggests
that the water was largely atmospheric and existed only during the
earliest times when the surface of the planet was completely molten.
Whether that is true or not is a key question.  If Venus ever did
possess surface water, it may possibly have had an early habitable
phase.  It is also possible that colliding comets brought additional
water to Venus after the surface crystallized, and that they created
bodies of standing water in which life might have been able to form.


ROSETTA TRIUMPHS AT ASTEROID LUTETIA
Science Daily

ESA's Rosetta mission has returned the first close-up images of the
asteroid Lutetia, showing that it is probably a primitive survivor
from the violent birth of the Solar System.  The images show that
Lutetia is heavily cratered, having suffered many impacts during its
4.5 billion years of existence.  As Rosetta drew close, a bowl-shaped
depression stretching across much of the asteroid rotated into view.
The images show that Lutetia is an elongated body, with its longest
dimension around 130 km.  The pictures come from Rosetta's OSIRIS
instrument, which combines a wide-angle and a narrow-angle camera.  At
closest approach, details down to a size of 60 m can be seen over the
entire surface of Lutetia.  Rosetta raced past the asteroid at 15
km/s, completing the fly-by in just a minute, but the cameras and
other instruments had been working for hours and in some cases days
beforehand, and will continue afterwards.  Ground telescopes have
shown Lutetia to present confusing characteristics.  In some respects
it resembles a 'C-type' asteroid, a primitive body left over from the
formation of the Solar System.  In others, it looks like an 'M-type',
which have been associated with iron meteorites, are usually reddish
and are thought to be fragments of the cores of much larger objects.

The fly-by marks the attainment of one of Rosetta's main scientific
objectives.  The spacecraft will now continue to a 2014 rendezvous
with its primary target, Comet Churyumov-Gerasimenko.  It will then
accompany the comet for months, from near the orbit of Jupiter
down to its closest approach to the Sun.  In 2014 November
Rosetta will release its Philae lander to land on the comet nucleus.


PROCESSES OF MASSIVE-STAR FORMATION
Joint Astronomy Center, Hilo, Hawaii

Astronomers using the United Kingdom Infrared Telescope (UKIRT)
believe that they have identified the leading mechanism by which
massive stars form in our Galaxy: by collecting matter via discs
around their equatorial regions.  That was revealed by the detection
of gas outflows and shocked regions associated with massive young
stars in formation, located in clouds of gas and dust.  Scientists
know that lower-mass stars like our Sun form by gravitational collapse
of material inside clouds of gas and dust in space.  The gas and dust
spiral down onto the equatorial regions of the young star by a
process known as accretion.  At the same time, the accreting young
stars drive high-velocity jets of gas ('outflows') which radiate at
infrared wavelengths, so astronomers can use observations in the
infrared to search for not only the youngest stars, but also evidence
of the accretion process.

There have been misgivings over whether stars with masses larger than
10 times the mass of our Sun form in the same way, as it has been
supposed that the extreme energy output of such stars, which start
nuclear burning in their cores even before they complete their growth
through accretion, would prevent further growth by blowing away the
accretion discs.  Hence, alternative mechanisms such as mergers of
lower-mass stars have been suggested as the main way in which massive
stars form.  The presence or absence of outflows from massive young
stars should tell us whether accretion or some other method leads to
their formation.  Most of the massive young stars being formed are
confined to the Galactic plane and are located in molecular clouds
extending over several or even tens of light-years.  They are hidden
behind large amounts of gas and dust, which hamper their detection at
visible wavelengths but are penetrated by infrared light.  The UKIRT
observers looked at 50 bright young stellar objects; 38 of them showed
molecular line emission, in most cases arising from outflows.  Within
the sample, the outflows are seen to be well-defined irrespective of
the energy output of their central young stars and are nearly as
well-defined as those from low-mass stars.  The outflows appear to be
driven by jets like those from low-mass stars.  The astronomers have
concluded that massive stars up to at least 30 times the mass of the
Sun form through disc accretion.


ORIGIN OF MILKY WAY'S ANCIENT STARS
RAS

Scientists at Durham and collaborators at the Max Planck Institute and
Groningen University in Holland have tried to make computer
simulations of the beginnings of our Galaxy.  The simulations have
suggested that ancient stars found in a stellar halo of debris
surrounding the Milky Way were ripped from smaller galaxies by the
gravitational forces generated by colliding galaxies.  Cosmologists
think that the early Universe was full of small galaxies which led
short and violent lives, colliding with one another and leaving behind
debris which eventually settled into more familiar-looking galaxies
like the Milky Way.


UNRAVELLING THE NATURE OF HANNY'S VOORWERP
ASTRON, Dwingeloo, Netherlands

A group of researchers has made high-resolution radio observations
of the region of space around Hanny's Voorwerp (Hanny's Object), the
curious, greenish gas cloud discovered by Dutch schoolteacher Hanny
van Arkel.  The astronomers undertook an observational campaign at
radio wavelengths in which several radio telescopes across Europe and
the United Kingdom were linked together in real time in order to
obtain a detailed picture of the central region of the adjacent galaxy
IC 2497.  They observed a field a few arcseconds across, with a
spatial resolution of about 70 milliseconds.  The observations show
two bright and very compact sources with broadband spectra that argue
for the existence of an active galactic nucleus (AGN) at the centre
of IC 2497.  One of the sources appears to be identifiable with a
supposed black hole at the centre of the AGN itself, while the other
is likely to be the result of an energetic jet expelled by the black
hole and now interacting with dense gas that surrounds IC 2497.  The
radiation from the AGN is believed to heat Hanny's Voorwerp to a
temperature above 10,000°.

It also appears that surrounding the AGN is a lot of extended radio
emission.  The researchers argue that it is associated with a nuclear
starburst.  Astronomers knew that IC 2497 is forming stars, but were
surprised to find that the star formation seems to be concentrated in
a very small central region, only 1000 parsecs across.  It is fairly
unusual to find both vigorous star formation and AGN radio activity in
the same system and on similar scales.  The radio observations
indicate that in the central region IC 2497 is producing stars with a
total mass of the order of 70 Suns every year -- a high rate, about 6
times higher than in the nearby starburst galaxy M82.

The observations support the group's earlier hypothesis that a hidden
AGN in the centre of IC 2497 is ionizing a distinct region of gas that
surrounds that galaxy.  That distinct region is what is known as
Hanny's Voorwerp.  Such phenomena must be rare in the local Universe
because they depend on a specific geometry of the observer, galaxy,
and gas, plus the interaction of several galaxies in the field in
order to fuel the AGN and the starburst, and to create the gas
reservoir that forms part of the Voorwerp.


VOYAGER SPACECRAFT AT 12,000 DAYS
Science Daily

On June 28, the Voyager 2 spacecraft had been operating continuously
for 12,000 days.  For nearly 33 years, the venerable spacecraft has
been returning data about the outer planets, and the characteristics
and interaction of the solar wind between and beyond the planets.
Among its findings, Voyager 2 discovered Neptune's Great Dark Spot and
its 450-m/s winds.  The two Voyager spacecraft have been the longest
continuously operating spacecraft in deep space.  Voyager 2 was
launched on 1977 August 20; Voyager 1 was a little later, on
1977 September 5, so it reached its 12,0000 days on July 14.  The two
spacecraft are the most distant man-made objects, out at the edge of
the heliosphere -- the bubble that the Sun creates around the Solar
System.  Having travelled more than 21 billion kilometres on its
winding path among the planets towards interstellar space, Voyager 2
is now nearly 14 billion kilometres away; a signal from the ground,
travelling at the speed of light, takes about 12.8 hours one-way to
reach it.  Voyager 1 is even further away, more than 17 billion
kilometres.


Owing to holidays, the next scheduled edition of the bulletin will
appear on August 15.


Bulletin compiled by Clive Down

(c) 2010 the Society for Popular Astronomy

--
Good Clear Skies
--
Astrocomet
--
Colin James Watling
--
Profile: http://www.google.com/profiles/astrocomera
--
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/
--
Information: http://www.clubbz.com/club/2895/LOWESTOFT---3054/Lowestoft%20And%20Great%20Yarmouth%20Regional%20Astronomers%20(Lyra