ASTR1001 Planet Zog: Background Briefing and First Data Release

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ASTR1001 Planet Zog Background Briefing and
First Data Release
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The Planet Zog

• Imagine that you live on the distant planet Zog
  far away in a space-time very different from our
  own. Zog is very much like the Earth you have a
  technology virtually identical to our own. All
  the laws of Physics, as you measure them in the
  Zoggian laboratories, seem identical to the laws
  we measure on Earth.
• The one thing that is very different is the night
  sky...

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The stars look similar to Earths, but there is
no Milky Way.
Instead, north Zog astronomers see the awesome
sight of the Greater Milkstain
With its brilliant off-centre blue spot.
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Southern hemisphere Zog astronomers see the
equally brilliant southern blue spot.
Recent Bubble Space Telescope observations have
shown that the southern blue spot also has an
off-centre milkstain associated with it. But the
Southern Milk Stain is very very much smaller and
fainter than its northern counterpart.
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Celestial Coordinates.

• The two blue spots are diametrically opposite on
  the sky (and hence can never both be seen at the
  same time, except by astronauts).
• They are used as the origin of the celestial
  coordinate system

Declination 90 for northern blue spot, 0 for
the celestial equator.
Both milkstains extend away from the two blue
spots in the same direction (though the GMS
extends further).
Right Ascension 0 to 360. Zero axis is along the
long axis of the two milkstains.
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The Milkstains

• The Greater Milkstain (GMS) has been known for
  centuries to break up into literally millions of
  stars when viewed with even a pair of binoculars.
  There appear to be about ten millions stars in
  total.
• The Lesser Milkstain (LMS) does not break up into
  stars when observed with telescopes. It does,
  however, have some rather curious jet-like
  features emerging from it

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The Fuzzballs

• In addition to stars, some curious fuzzy objects
  are seen scattered, with roughly uniform number
  density, all around the sky. They are similar to
  the jet-like features extending from the Southern
  Blue Spot (SBS). They vary enormously in
  brightness and size, though the larger ones tend
  to be brighter. Faint fuzzballs greatly outnumber
  the bright ones. Most fuzzballs are brighter and
  bigger than the LMS.

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The Blue Spots

• Both blue spots are roughly equally bright. They
  do not vary in brightness. Both are about as
  bright as a full moon. They are not just dots
  they seem to consist of blue-white cores,
  surrounded by a paler fuzz that merges into the
  two Milkstains.

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Recent Observations

• We now present some recent observations made by
  Zoggian astronomers.
• Note that Zoggian astronomers use SI units, just
  like earthlings.

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Schnunka et al.

• Schnunka et al. (from Mt Ztromlo Observatory)
  recently carried out, and published, a rather
  interesting study of fuzzballs. They obtained
  images of fuzzballs using the Bubble Space
  Telescope (BST). They asked for observations of
  the ten brightest and ten faintest fuzzballs.
• The BST time allocation committee allocated half
  the time they asked for, allowing observations of
  ten fuzzballs in total (they were not convinced
  that the extra time would tell them anything
  interesting). The brightest five were taken from
  the Messier catalogue of bright fuzzballs.

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• The Bubble Space Telescope

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• They asked for observations of the ten faintest
  fuzzballs. Nobody has ever found the faintest
  fuzzballs the harder you look, the more faint
  fuzzballs you see. Nobody has yet found a lower
  limit on how faint they can get. Also, really
  faint fuzzballs are very hard to observe you
  need a huge telescope and a lot of exposure time.
  The time allocation committee therefore chose to
  give them observations of the five faintest
  fuzzballs in the New Fuzzball Catalogue, a
  catalogue of the thousand brightest fuzzballs in
  the sky.
• All observations were made though a filter (the V
  filter) that allows light in the wavelength range
  0.45-0.55 ?m to pass. Fluxes are quoted in W m-2
  nm-1, ie. the rate at which energy hits a unit
  area of the telescope, per unit wavelength range
  the instrument is sensitive to.

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• Here is the picture of the brightest fuzzball
  M23. Note that it is clearly made up of stars
  around 10 million of them.

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• Here is the picture of the faintest fuzzball NFC
  761. Note the lack of detail even with the
  Bubble Space Telescope, you cannot pick out
  details.
• The faintest fuzzballs appear considerably
  smaller than the near ones. Their central surface
  brightness (Watts per square arcsecond), however,
  is roughly the same.

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• In all cases, the surface brightness of the
  fuzzballs declines with distance from the centre
  of the fuzzball r as
• The colours of the inner and outer parts of the
  fuzzballs are fairly similar, though the insides
  do appear to be marginally bluer in some cases.

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Snag et al. (Max Zlank Institute)

• These researchers recently published spectra of
  four fuzzballs in the jet extending from the
  Southern Blue Spot.
• Their observations were taken with the Kemini
  Telescope.

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• The Kemini Telescope

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• They obtained spectra of four fuzzballs from one
  of the biggest jets, as shown below. The other
  fuzzballs were much fainter and would have taken
  more telescope time than was available to obtain
  adequate spectra.

G1
G2
G3
G4
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• All four fuzzballs had similar spectra spectra
  resembling those of typical stars.

Relative Flux
Observed Wavelength (nm)
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• The only significant differences between the
  spectra were that the lines were shifted. For
  example, hydrogen normally emits strongly (in the
  lab) at a wavelength of 486.1nm (due to electrons
  jumping from energy level 4 to energy level 2),
  and Oxygen at 372.7 nm. Here are the observed
  wavelengths of these lines

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Hoddly et al. (Green Mountain Observatory)

• These researchers recently used the Bubble Space
  Telescope to measure the parallaxes of ten nearby
  stars. The ten brightest stars near declination
  zero were chosen. Measurable parallaxes were
  determined for all ten stars it turns out that
  they are all at a distance of around 1017m. All
  ten have measured fluxes of around 10-11 W m-2
  nm-1 in the V band.
• One of these ten stars is a known variable it
  pulses every three hours. The other nine are not
  known to be variable. The variable star has a
  maximum flux of 10-11 W m-2 nm-1 .

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Costello et al. (Zarvard University)

• This group didnt make any new observations.
  Instead, they extracted information on the twenty
  brightest fuzzballs from the archives of the IRAS
  (Infra Red Astronomy Satellite) spacecraft.
• The IRAS data was easy to obtain during its 2
  year mission IRAS photographed the whole sky
  they just had to extract the relevant scans from
  ZASAs (the Zog Air and Space Administration)
  computer archives.
• IRAS mapped the whole sky at a wavelength of 60
  microns.

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• The IRAS images were very disappointing. None of
  the fuzzballs emitted any detectable mid-IR flux.
  The only thing detected was the Southern Blue
  Spot, and even it was quite weak in the mid-IR.
• Mid-IR radiation is emitted by objects with
  temperatures of around 100K. This usually means
  interstellar dust stars are too hot to emit much
  mid-IR flux. So whatever the fuzzballs are, they
  do not contain much interstellar dust.
• Dust normally forms wherever stars are dying the
  winds from old stars (planetary nebulae) contain
  heavy elements synthesised by nuclear fusion in
  their cores, and as the winds cool, these heavy
  elements condense out as tiny grains of graphite
  and silicates.
• As these dust grains float around in space,
  starlight heats them up to around 100K, and they
  emit copious mid-IR radiation. But not in the
  fuzzballs.
• Dust can be destroyed either by shockwaves, or by
  prolonged exposure to high temperature gas (one
  million degrees or more).

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Lightnarg Woolley (Zalifornia Institute of
Technology)

• This group have recently gone observing, with the
  aim of getting spectra of as many fuzzballs as
  possible.

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• The spectra were taken with the Mt Ztromlo 2.3m
  Advanced Technology Telescope. Unfortunately,
  this observatory is famous for cloudy weather
  they only managed to get spectra of five
  fuzzballs and the Southern Milkstain through gaps
  in the clouds.

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• All five fuzzballs and the Southern Milk Stain
  have spectra that look like this. The SMS was far
  fainter than the fuzzballs.

Relative Flux
Observed Wavelength (nm)
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They measured the wavelength of the H-beta line
of Hydrogen a spectral line with a laboratory
wavelength of 486.13 nm. In all their spectra,
this line had moved in wavelength one way or
another by a small amount.
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Hooligan Thug, Zliverpool Tech

• This group have spend the last year searching for
  supernovae with the 1m telescope at Siding Zpring
  Observatory. They slaved away at the telescope,
  taking thousands of pictures of various
  fuzzballs, looking for something that changed.
• They found four supernovae. One was in the well
  known bright fuzzball M86. Three were found in
  fainter fuzzballs in M12, NFC64 and,
  remarkably, in a fuzzball in one of the jets
  protruding from the Northern Blue Spot B3.

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• The 1m

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• Here are the before- and after images of the
  supernova in NFC64. The top image was taken while
  the supernova was at maximum brightness - the
  bottom one before it had exploded.
• All the supernovae had very similar spectra, and
  they all showed the same pattern of brightening
  and fading.

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• Here is a table of the peak brightness reached by
  the various supernovae.

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Chuck Bride, Louiziana College of TAFE

• These eminent researchers obtained spectra of the
  Greater Milkstain, and of both blue spots, using
  the William Herzhal Telescope in the Izlas
  Canarias.

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• The William Herzhel Telescope

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• The GMS is made up of many individual stars. To
  avoid being biassed by some particular star, the
  spectrograph slit was scanned across the GMS.
  Here is the integrated Spectrum. It has no red-
  or blue-shift.

Relative Flux
Observed Wavelength (nm)
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• The spectra of both blue spots were identical.
  There are no bumps or wiggles in the spectrum to
  measure a redshift from.