Topic: Late March Astronomy Bulletin

[Clive]

NEW BACTERIA DISCOVERED IN STRATOSPHERE
Science Daily

The Indian Space Research Organization has reported the discovery of
new species of bacteria in samples collected by a balloon in the
stratosphere.  That layer of the Earth receives heavy doses of
ultraviolet radiation, enough to kill most organisms.  In their
analyses of the retrieved samples, microbiologists detected 12
bacterial and six fungal colonies.  Of them, three bacterial colonies
were new species.  Indian scientists named one of them Janibacter
hoylei, after astrophysicist Fred Hoyle.  It is extremely unlikely
that these organisms are extra-terrestrial; they are likely to have
originated from soil on the Earth.  Bacteria are often found in the
stratosphere, and most can be traced to wind-borne dust particles.
That the new species were previously unknown means little, since
scientists have identified only about 1% of all Earthly bacteria, and
although the species had not been seen previously, their gene
sequences were familiar; they represent a variation on known life,
rather than an entirely new form.


ANOTHER ASTEROID PASSES BY
Spaceweather.com

Newly-discovered asteroid 2009 FH passed by the Earth on March 17 at
a distance of only 85,000 km (0.00057 AU), only a little more than
twice the height of a geosynchronous communications satellite.  This
is the second time in March that an asteroid has flown so close to
the Earth.  As described in the last Bulletin, on March 2 one passed
only 72,000 km away.  Measuring some tens of metres in diameter, the
two are approximately Tunguska-class objects, so they do not pose a
global threat but would cause local damage if they actually hit the
Earth.  In the past, asteroids of that size often passed unnoticed,
but recent improvements in asteroid surveys have resulted in growing
numbers of space rocks caught in the act of near-Earth fly-bys.


SALTY WATER PROBABLY PRESENT ON MARS
University of Michigan

Salty, liquid water has been detected on a leg of the Mars Phoenix
Lander, according to analysis by a group of mission scientists.  This
is the first time that liquid water has been detected and photographed
outside the Earth.  Previously, scientists believed that water existed
on Mars only as ice or water vapour because of the planet's low
temperature and atmospheric pressure.  They thought that ice in the
current Martian climate could sublimate, or vaporize, but they did not
think it could melt.  The new analysis shows how that assumption may
be incorrect.  Temperature fluctuations in the arctic region of Mars
where Phoenix landed and salts in the soil could create pockets of
water too salty to freeze in the climate of the landing site.

Images of one of the lander's legs show droplets that grew during the
polar summer.  From the temperature of the leg and the presence of
large amounts of perchlorate salts in the soil, scientists believe
that the droplets were most likely salty liquid water and mud that
splashed onto the spacecraft when it touched down.  The lander was
guided down by rockets whose exhaust melted the top layer of ice below
a thin sheet of soil.  Some of the mud droplets that splashed onto the
lander's leg appear to have grown by absorbing water from the
atmosphere.  Images suggest that some of them darkened, then moved and
merged -- physical evidence that they were liquid.

The 'wet-chemistry' lab on Phoenix found evidence of perchlorate
salts, which probably include magnesium and calcium perchlorate
hydrates.  Those compounds have freezing temperatures of about -70 and
-75 C respectively. The temperature at the landing site ranged from
approximately -20 to -95 C, with a median temperature around -60.
Temperatures at the landing site were mostly warmer than that during
the first months of the mission.  Thermodynamic calculations offer
additional evidence that salty liquid water can exist where Phoenix
landed and elsewhere on Mars.  The calculations also predict a droplet
growth rate that is consistent with what was observed.


DARK MATTER MAY PRESERVE SMALL GALAXIES
RAS

The Hubble telescope, observing the 'nearby' Perseus galaxy cluster,
has discovered a large population of small galaxies that have remained
intact while larger galaxies around them are being distorted or
disrupted by the tidal effects of the gravity of neighbouring
galaxies.  A suggested explanation for the comparative stability of
the small galaxies is that they are much more massive than they
brightness might lead one to expect, that is to say, they contain a
great deal of dark matter.  'Dark matter' simply means matter whose
mass is greater in relation to its light output than is the case with
the Sun.  The term does not warrant the mystery with which popular
expositions often invest it, although in a number of instances,
including the present one, it is not apparent exactly what the nature
of the under-luminous matter is.


RED SUPERGIANTS PRODUCED SUPERNOVAE
Science Daily

Stellar energy comes mostly from the 'burning', or tranmutation, of
hydrogen to helium - a process called nuclear fusion - in a small core
in the interior of the star.  Most of the energy available from the
hydrogen has been released by the time it has become helium, but
smaller amounts can be released by fusion of the atomic nuclei into
elements heavier than helium.  While that is happening, the outer
layers of the star swell up to an enormous size, turning the star into
a red giant or supergiant.  The burning process cannot go further than
iron, whose nuclei have the lowest energy of all.  Even if a star
managed to get its core into pure iron, however, it might still be
able to go on shining for a 'little while', by producing energy in
shells surrounding the then-dead core.  It is at such a stage that a
massive star blows up as a supernova: the equations of the people who
model stellar evolution show how that can happen, even though it is
difficult to give a simple physical explanation of why it should
occur.

It is obviously of interest, not least to those who try to model the
events, to know just what the star looks like to the outside world
when the supernova catastrophe is about to happen, particularly since
doubts have been expressed over the idea that red supergiants explode
as supernovae.  Now, astronomers using images from the Hubble
telescope and the Gemini Observatory have observed two stars that
exploded as supernovae.  By analysing images of the same section of
the sky before the explosions, the researchers could see which stars
might have gone supernova.  Picking out individual stars a long way
away and pinpointing exactly which star it was that exploded is
difficult.  It becomes easier several years after the supernova has
exploded, because by then its clouds of dust and gas have largely
blown clear, so the region can be observed again and it may then be
possible to see exactly which star has disappeared.  In the two cases
that have now been investigated, the stars that had disappeared after
the supernova explosions were red supergiants, a result that goes a
long way towards confirming the hypothesis that it is red supergiant
stars that create type-II supernovae.


RAPID CHANGES IN RADIATION EMITTED BY BLAZAR
Goddard Space Flight Center

An international team of astrophysicists using telescopes on the
ground and in space has observed surprising changes in radiation
emitted by an active galaxy.  The picture that emerges from their
first simultaneous observations with optical, X-ray, and new-
generation gamma-ray telescopes is much more complex than they
expected.  The galaxy in question is PKS 2155-304, a type of object
known as a blazar, thought to be emitting bi-polar jets one of which
is pointing straight towards us.

PKS 2155-304 is located 1.5 billion light-years away in the southern
constellation Piscis Austrinus, and is usually a detectable but faint
gamma-ray source.  But when its jet undergoes a major outburst, as it
did in 2006, the galaxy can become the brightest source in the sky at
the highest gamma-ray energies scientists can detect.  Even from
strong sources, there is only about one gamma ray of such high energy
per square metre per month arriving at the top of the atmosphere.
Atmospheric absorption of such a gamma ray creates a short-lived
shower of subatomic particles which produce a faint flash of blue
light called Cerenkov radiation.  An array of telescopes in Namibia
captured such flashes from PKS 2155-304.  For a 12-day period last
year, the telescopes monitored PKS 2155-304 in its quiet, non-flaring
state.  The results were surprising.  During flaring episodes of that
and other blazars, the X-ray and gamma-ray emission rise and fall
together, but when PKS 2155-304 is in its quiet state they do not do
so.  Also, the galaxy's visible light rises and falls with its
gamma-ray emission.  All that can be said about it at present is that
the various constituents of the jets in blazars seem to interact in
fairly complicated ways.


RUSSIA TO APPROVE NEW MOON ROCKET
BBC News

Russian space officials are to select the winning proposal for a new
rocket intended to carry cosmonauts on missions to the Moon.  This
will mark the first time since 1964 that the Russian space programme
has made the Moon a main objective.  It will be only the second
time since the collapse of the Soviet Union that Moscow has endorsed
the development of a new space vehicle.  The rocket is expected to
fly its first test mission in about 2015.

According to the objectives given by the Russian space agency, a
future rocket should be able to hoist a payload three times heavier
than Russia's veteran Soyuz spacecraft, including twice the number of
crew, and use environmentally friendly propellents.  The development
of the new rocket should be accompanied by work on Russia's next-
generation manned spacecraft, which will use it to get into orbit.
Russian space officials say the yet-to-be-named rocket should carry
its first manned spacecraft in 2018.  The project is timed to coincide
approximately with NASA's plans to send astronauts to the Moon by
2020.  However, in what seems like a case of history repeating itself,
Russia is starting late in its bid to beat the US -- and potentially
China -- to the Moon.  In 1961, President Kennedy met the Soviet
challenge in space by launching the original US lunar effort.  Yet the
Soviet government waited until 1964 before committing itself to the
costly expenditure of a manned landing.  The Kremlin ultimately
aborted the effort after Apollo 11 touched down on the Moon first.  In
the new 21st-century Moon race, the US, Europe, China, India and Japan
had all declared their intention to explore the Moon, before the
recent Russian announcement.


ESO'S FIRST OBSERVATORY CELEBRATES 40th ANNIVERSARY
ESO

ESO's La Silla Observatory, which became the largest astronomical
observatory of its time, is celebrating its 40th anniversary.  It
helped to keep Europe in the front line of astronomical research, and
is still one of the most scientifically productive ground-based
observatories.  Like other observatories in the same area, La Silla is
far from sources of light pollution and, like the Paranal Observatory
that houses the Very Large Telescope, it has some of the darkest and
clearest night skies on the Earth.  At its peak, La Silla had no fewer
than 15 telescopes, among them the first -- and, for a long time, only
-- southern telescope working in sub-millimetre wavelengths (the
15-metre SEST), and the 1-metre Schmidt telescope, which contributed
towards the first photographic mapping of the southern sky.