The Hubble Space Telescope - the first 10 years

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The Hubble Space Telescope - the first 10
years

• Our only optical telescope in space
• Why, when and how
• Observations
• Planets
• Stars
• Galaxies
• Cosmology
• The Next Generation Space Telescope

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HST .

• An Orbital
  Telescope
  (90mins/orbit)
• Launched
  April 24th 90
• Serviced
  mid-Dec 93
• Visible From
  Earth by Eye

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The Launch .

• April 24th 1990
• Space Shuttle
  Mission ST-31
• 10x faster than a
  rifle bullet !

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Overview .

• 2.4 metre
  mirror
• Solar Panels
  for energy
• 4 instrument
  payload
• Comms
• Shutter
• Gyros

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The Benefits of Space

• No atmosphere crystal sharp images
• No sky glow very deep images

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Hubble Trouble

• But,to our horror we discovered Hubbles mirror
  was the wrong shape !
• In 1993 a service mission (ST-62) was sent up to
  replace
  some of the
  optics
• Since then
  its worked
  perfectly
• Heres the
  difference gt

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Hubble Trivia

• Named after Edwin Hubble who discovered the
  expansion of the universe
• Project conceived in 1971
• Total cost around US 1 billion !
• Now Operational for 10 years
• Observed 14,000 objects
• Orbited the Earth 58,400 times
• Travelled 1.5 billion miles
• Can see back to when the Universe was 10 of its
  current age (13 billion years ago)

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Where HST has been looking

• This shows the places on the sky where HST has
  looked. Milky-way across centre.

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Our Solar System

• In our Solar System are 9 planets Mercury,
  Venus, Earth, Mars, Jupiter, Saturn, Uranus,
  Neptune and Pluto plus an asteroid belt, Kuiper
  belt, moons and of course the sun.
• HST cannot look at Mercury because it is too
  close to the sun and would damage the telescope.
• It has looked at everything else though gtgtgt

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Our Solar System with HST
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Comets

• Comets are gigantic icy rocks which whiz through
  the Solar System at v.high speeds.
• It is believed a comet killed the dinosaurs and
  the impact created the gulf of Mexico
• Thankfully Comet impacts are very rare.
• However In 1995 a comet hit Jupiter !

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The Impact of Fragment G

• Provided
  information
  on the
  rotation of
  Jupiters
  atmosphere,
  its
  thickness
  and its
  composition

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Stars

• Stars form from giant gas clouds floating in
  space
• The cloud first starts to collapse due to gravity
• When sub-clumps reach a sufficiently high density
  Nuclear fusion occurs bathing the region in
  radiation
• This radiation blows away any remaining dust
• Finally were left with a star cluster
• Eventually each star explodes (Supernovae)
• All that remains is a black hole, neutron star or
  white dwarf
• HST has looked at all stages of this process gtgtgt

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Stars Gas Collapses

• The Trifid Nebula
  A Stellar Nursery
• Gas is collapsing
  due to gravity
  and where it
  becomes dense
  enough stars are
  formed and
  nuclear fusion
  occurs

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Stars Stars Ignite

• The Eagle Nebula
• Radiation from the
  newly formed stars
  moulds the gas
  remaining into
  the spectacular
  gaseous pillars
  we see
  here

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Stars The First Stars

• An emerging star
  cluster NGC3603
• As the gas is blown
  away the newly
  formed star cluster
  becomes visible
• At this stage the
  light is dominated
  by the very hot but
  short-lived
  blue stars

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Stars A Cluster is formed

• A Star Cluster
• As the hot blue stars
  burn out we are left
  with a star cluster.
  All remaining
  gas is now
  blown far away
  and this cluster will
  stay like this for
  many billions of
  years

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Stars Stellar Outflows

• Eta Carinae
• Many stars form as
  binary systems, during
  the course of their
  active phases mass is
  often transferred
  from one star
  to the other. If
  this matter is accreted
  too fast it squirts out
  of the poles
  of the secondary
  star

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Stars Supernova

• Superova NGC6543
• Stars end their life-cycle
  by going Supernova or
  Nova depending on their
  initial mass
• The most massive go
  supernova and blow
  off their outer shell
  whilst the core collapses
  into a black hole

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Stars Planetary Nebulae

• The Spiral Nebula
• The shell of material
  blow off settles down
  and the remaining core
  can often pulsate if it
  is not massive enough
  to form a
  black hole

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Galaxies

• Galaxies consist of about 1billion stars
• Once called Island Universes(Kant)
• 3 main types
• Ellipticals (Smooth, Old and Red)
• Spirals (Bulge plus spiral arms)
• Irregulars (Newly formed or interacting)
• HST allows us to look closely at the regions
  where stars form and to see their structure back
  to when the Universe was young

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Galaxy Clusters

• Here we see a
  typical example
  of an elliptical galaxy
  (centre) and a
  spiral galaxy
  (right).
• Galaxies often form
  in groups of clusters.
  Here we see the nearby
  core of the Coma
  cluster of
  galaxies

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Galaxies and star-formation

• The smaller panel shows NGC4314 as viewed from
  the ground. The larger panel shows the core as
  seen by HST. The purple and blue regions indicate
  where star clusters are forming

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Peculiar Galaxies and mergers

• Galaxies are believed start from small sub-clumps
  which through merging build themselves up to
  giant ellipticals and spirals. Here we see the
  merger of two giant spirals which will one day
  become a giant elliptical. The core of each
  galaxy is seen in red and
  most likely each
  core
  contains a
  giant black hole.
• Our galaxy is on
  collision course
  with Andromeda
  and one day
  may
  look like this.

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The Hubble Deep Field

• The most famous single image is
  The Hubble Deep Field (150 orbits of data)
• It only covers 1millionth of the sky but
• Its the deepest image ever taken of the Universe
  looking back to when the Universe was
  1 billion years old (I.e., 10 of its
  current age)
• In it we see that the most distant galaxies are
  very irregular unlike the spirals and ellipticals
  we see todaygt GALAXIES FORMED VIA MERGERS
• With HST we finally see the main epoch of
  GALAXY FORMATION 8billion years ago

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The Hubble Deep Field

• The Deepest image ever taken of our Universe

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Galaxy Evolution

• From the Hubble Deep Field we see that galaxies
  look normal back until 30 of the age of the
  Universe at which point the number of Peculiars
  and mergers increases. This panel shows samples
  of galaxies at different ages
• starting from
• today and
• stretching back
• until the Universe
• was 10 of its
• current age.

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Cosmology

• There are 4 numbers that define our universe
• 1) The Expansion Rate (Hubble Constant)
• 2) The Density of Matter
• 3) The Density of Radiation
• 4) The Density of Space-time
• The Hubble Space Telescope is measuring (1) the
  expansion rate of the universe today !
• The other parameters are being measured from
  other satellites which are looking at the Cosmic
  Microwave Background

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An Analogy (CarUniverse)

• Think of a car heading down the street out of
  control with the brake, hand brake and
  accelerator all jammed on !
• We want to know whether its going to stop, get
  faster or stay at a constant speed !
• Whether this happens is determined by its current
  speed, and the battle between the brakes and the
  accelerator !

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The Car and the Universe

• The car is the Universe and we want to know
  whether the Universe is going to stop expanding
  and recollapse or continue to expand for ever.
• The Hubble constant is the cars speed right now
• The density of matter is the footbrake
• The density of radiation is the handbrake
• The density of Spacetime is the accelerator (also
  known as the Cosmological Constant)
• Measuring the Hubble Constant is a crucial step

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The HST Key Program

• Aim, to measure the expansion rate of the
  Universe gt the age of the universe!
• To do this we need a very accurate distance
  measurement, the velocity we already know
• But how do we measure distances ?
• Well some stars are known to pulsate at a rate
  which depends on their brightness.
• We can use this to calculate the distances to
  nearby galaxies.
• In the case M100 in the Virgo cluster

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The Age of the Universe

• All galaxies are moving away from us
• The furthest galaxies move away faster
• Hubbles law gt Universal Expansion
• If we measure a galaxies speed and its distance
  we can calculate how long its been travelling
  for (I.e., timedistance/velocity).
• All galaxies gives us the same answer !
• This is an approximate age of the Universe, the
  point in space-time from which all matter
  originated
• (as this ignores any braking and accelerating)

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Calculating Distances

• If you move an object away it gets fainter
• Once its 10x further away it is 100x fainter
• Hence if we know how bright a star SHOULD be and
  we measure how bright it ACTUALLY is we can
  estimate the distance
• This relies on finding stars with KNOWN
  brightness and luckily their exist a class of
  star known as Cepheids which pulsate according to
  their brightness
• We can use these to measure distances

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The Galaxy M100

• The galaxy M100
• lies in the nearby
• Virgo cluster, we
• know how fast
• Virgo is moving
• so now all we need
• is its distance to get
• the age of the
• Universe

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Finding the Cephieds

• To measure the distance we need to find Cepheids,
  variable stars which pulsate according their
  brigthness. To do this we need to
• observe M100 many
• times and look for
• stars whose
• brightness varies
• periodically. Heres a
• Cepheid found on the
• outskirts of the galaxy

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Monitoring their Brightness

• Once a Cepheid has been found we must measure its
  brightness frequently to determine the period
  (which tells us its INTRINSIC brightness) and by
  comparing
• this to its
• APPARENT
• brightness we can
• estimate the
• distance to M100.
• Even with HST
• this is very hard

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Distance to M100

• Heres the equation that we use
• m-M5log(d)-5
• mThe APPARENT Brightness in logarithmic units
• MThe INTRINSIC Brightness in logarithmic units
• d The distance in parsecs (1parsec3.3 light
  years)
• The APPARENT brightness we measure from the
  image, the INTRINSIC brightness we calculate from
  the PERIOD of the Cephied
• Eventually we get the crucial distance to M100

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The Hubble Constant

• HST provides a distance to M100 of
  16 Mpc 50 million light years !
• From the ground we can measure the speed with
  which this galaxy is moving away 1250 km/s I.e.,
  Every day M100 gets 108 million km further away !
  
• The ratio gives us the Expansion Rate of the
  Universe 78 km/s/Mpc
• It also gives an approximate age of the
  universe, remember t d/v which gives about 10
  billion years

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The Universe Today

• Thanks to the Hubble Space Telescope we have a
  picture in which our universe formed 10 billion
  years ago and 2 billion years into this the
  galaxies formed through mergers of smaller
  building blocks into the large and well ordered
  galaxies we see around us today - this new
  perspective into our Universe has only been
  possible by looking through the eye of the Hubble
  Space Telescope.
• So what is the next big question ?

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The Fate of the Universe

• Remember the Car hurtling our of control ?
• HST has measured its speed today
• We still have three more parameters to find
• The Density of Matter the footbrake
• The Density of Radiation the handbrake
• The Density of Space-Time the accelerator
• To measure these requires a combination of even
  more sophisticated telescopes and satellittes

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The Next Generation Space Telescope

• NASA is planning an 8-metre telescope, a
  collecting area 11x large the the HST. To be
  launched in 2015. This will see even further and
  over larger chunks of sky. It will also see in
  other wavelengths and in particular the Infrared.
• This telescope will
• be sent into deep
• space and a solar
• shield will keep it
• protected from the
• sun

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Finally my favourite image

• Gravitational Lensing by a Galaxy Cluster

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THE END

• Cosmology and Astronomy is an exciting science
  entering a golden era of discovery. Soon we will
  know either the fate of the Universe or well
  overturn the Big Bang model. Either way its an
  exciting time and an exciting place to be.
• HST Websites
• http//hubble.stsci.edu/
• http//heritage.stsci.edu/
• http//www.stsci.edu/
• http//opposite.stsci.edu/pubinfo/picture.html