Topic: Late July Astronomy Bulletin

[Clive]

HUBBLE DISCOVERS A NEW MOON AROUND NEPTUNE
NASA

The Hubble telescope has discovered a new satellite -- the 14th -- of
Neptune.  Designated S/2004 N 1, is estimated to be no more than 12
miles across, making it the smallest known moon in the Neptunian
system.  It is so small and dim that it even escaped detection by the
Voyager 2 spacecraft when it flew past Neptune in 1989 and surveyed
the planet's system of moons and rings.  Astronomers found the moon on
July 1, while studying the faint arcs, or segments of rings, around
Neptune.  It has a circular orbit, and completes one revolution around
Neptune every 23 hours.


STEAM OBSERVED ON EXTRA-SOLAR PLANET
RAS

Since the early 1990s scientists have found almost 1000 'exo-planets'
in orbit around other stars.  They are mostly much larger than the
Earth, and many are much closer to their stars than we are to the Sun,
leading them to be described as 'hot Jupiters'.  Now astronomers have
detected the spectrum of water molecules in the atmosphere of one of
them.  They looked, with an infrared spectrometer called CRIRES on the
VLT in Chile, at the exo-planet HD 189733b, that orbits its star
every 2.2 days and is heated to over 1000°C.  Astronomers usually do
not see the actual exo-planets, but infer their existence by measuring
their gravitational influence on the stars about which they orbit, a
reflex motion that is only a matter of metres per second.  In this
case, however, the team, led from Leiden University, managed to
measure the velocity of the planet itself, about 110 km/s, even though
it is nearly a thousand times fainter than the star, by observing
water molecules in its spectrum.  It seems likely that some other
exo-planet atmospheres will also be detectable in the same way.


HUBBLE SEES A BLUE PLANET
NASA

Astronomers working with the Hubble telescope have deduced that the
planet HD 189733b, referred to in the preceding item and one of the
closest exo-planets that can be seen in transit cross the face of its
star, is cobalt blue in colour.  If seen directly, that planet would
look like a deep blue dot, reminiscent of the Earth as seen from
space.  Although the planet resembles the Earth in terms of colour, it
is not Earth-like, being only 2.9 million miles from its parent star
and dreadfully hot.  In 2007, the Spitzer space telescope managed to
measure the infrared heat from the planet, leading to one of the first
temperature maps for an exo-planet. The map shows day-side and
night-side temperatures to differ by about 300°C.  That difference
could be expected to cause fierce winds to roar from the day side to
the night side.  It would not be a homely place to live.


ALMA OBSERVES STAR-FORMING REGION
ESO

The most massive and brightest stars in the Galaxy form within cool
dark clouds, which make it difficult to see exactly what is happening.
One such cloud is called Spitzer Dark Cloud (SDC) 335.579-0.292; it is
about 11,000 light-years away.  ALMA observations, made with just a
quarter of the eventual complete array, show details of the motions of
the filamentary network of dust and gas, and indicate that a lot of
gas is flowing into a central compact region.  The cloud is thought to
have a mass of over 500 times the mass of the Sun and is still
growing.  It is is expected eventually to give birth to a brilliant
star with up to 100 times the mass of the Sun.


A LOT OF DUST AROUND SUPERNOVA 1987A
RAS

Surprisingly low temperatures detected in the remnant of the supernova
1987A may help to explain why space is so abundant with dust grains
and molecules.  In 1987, an explosion of a massive star occurred in
the Large Magellanic Cloud, 'only' 170,000 light years away.  25 years
later, astronomers have used the Herschel space observatory and ALMA
to study the supernova remnant.  They found unexpectedly cold
molecules and dust.  The explosion observed in 1987 scattered elements
made by the star into space in the form of a very hot plasma.  The gas
has now cooled to temperatures between -170 to -250 degrees Celsius.
That is surprisingly cold, comparable to the icy surface of Pluto at
the edge of the Solar System.  The gas has formed molecules and some
has even condensed into solid grains of dust.  The Herschel
observations show that the supernova produced dust and solid material
equal to about 3/4 of the mass of the Sun.  Previously, scientists
have believed that supernova remnants contain only very energetic
atomic gas, detectable at X-ray wavelengths.


OPPORTUNITY'S IMPROBABLE ANNIVERSARY
NASA

The 'Opportunity' rover on Mars was designed only for a 3-month
mission on the hostile Martian surface.  Yet on July 7 there was
celebrated the tenth anniversary of its launch and more than 9 years
on Mars.  The rover is currently en route to 'Solander Point', a place
on the rim of Endurance Crater where interesting-looking areological
layering is exposed for investigation.  After nine-plus years of
travelling, Opportunity recently set the record for the US space
programme's mileage on another planet.  That occurred on May 15, when
the rover drove 80 metres, bringing its total distance to 35.76 km.
The previous mark had been held by the Apollo 17 moon rover, which
astronauts drove for 35.74 km across the lunar surface in 1972.

Solander Point, where Opportunity is heading now, has two main
attractions.  First, it has a thick series of strata to look at, and
secondly, there are north-facing slopes where the rover can tilt its
solar panels toward the Sun and hope to ride out the coming winter.
The minimum-sunshine days of this sixth Martian winter for Opportunity
will come next February.  If Opportunity survives another year, the
rover might yet break the 40-year-old all-time extra-terrestrial
driving record set by Lunokhod 2, a Soviet robotic vehicle that
travelled an estimated 42 km across the Moon in 1973.


DOUBLE-SIZED SUCCESSOR PLANNED FOR LIVERPOOL TELESCOPE
RAS

A successor to the present largest fully robotic telescope is being
planned.  The Liverpool Telescope (LT) is a 2-metre optical telescope
that has been in operation on La Palma since 2004.  A useful feature
has been its ability to react quickly to newly discovered or transient
events, such as gamma-ray bursts (GRBs).  It has also been used by
more than 2000 schools as an 'outreach programme'.  Now, the community
is being consulted on its successor, LT2.  Plans for it are being
developed by the Astrophysics Research Institute of Liverpool John
Moores University, which owns and operates the LT.  LT2 will be a
4m-class telescope, and the preferred location is again La Palma.

Like the existing telescope, LT2 will be fully robotic and will be
able to make rapid and flexible observations to capitalize on
discoveries made elsewhere.  That will become increasingly important
as more large-scale surveys begin.  From around 2020, the 'Large
Synoptic Survey' telescope is hoped to survey the entire southern sky
every few nights; but it seems not to have been noticed that that will
be rather at cross purposes with LT2, which will not be well placed to
follow up on southern objects.  All the same, it is claimed that LT2
will be able to slew extremely rapidly to a new object very soon after
receiving a 'trigger' from elsewhere, in order to catch the light from
transient objects that fade extremely rapidly, like GRB after-glows.
The aim is for LT2 to be able to set on the object and start making
follow-up observations in only about a minute.  There will evidently
be scope for the appointment of a ruthless administrator who will have
a particular interest in that sort of object and be in the fortunate
position of being able to give over-riding priority to it.  The
interests of the poor observer whose work may be fatally compromised
when the telescope is suddenly snatched away without any warning will
presumably take a back seat.