Beeps, Flashes, Big stars work much faster: Bangs and Bursts.

1,000,000 100,000 100,000 100,000

and Chirps.

Forever Peter Watson

3 hours!

Live fast, Die Young! Peter Watson, Dept. of Physics

Change colour, size, brightness •Vast majority of stars are boring: “main- sequence” (aka middle- class) changing very slowly.

•Some oscillate: e.g Cepheids

•Large bright stars change by factor 3 in brightness

Peter Watson Peter Watson

If Stars are large....

• we get supernovae • 6 visible in Milky Way over last 1000 years •well understood: work by blocking mechanism • SN 1006: Brightest •very important since period is proportional to Supernova. intrinsic brightness: • Can see remnants of the expanding •i.e. measure the apparent brightness, the period tells shockwave

you the actual brightness, so you know how far away Frank Winkler (Middlebury College) et it is al., AURA, NOAO, NSF

Peter Watson Peter Watson Remnant of a very Tycho’s old SN Supernova • Part of the veil nebula in X-rays in Cygnus (1572)

Sara Wager NASA / CXC / F.J. Lu (Chinese Academy of Sciences) et al.

Peter Watson Peter Watson

The Crab (M1) •Recorded by Chinese astronomers "I humbly observe that a guest star has appeared; above the star there is a feeble yellow glimmer. If one examines the divination regarding the Emperor, the interpretation [of the presence of this guest star] is the following: The fact that the star has not overrun Bi and that its brightness must represent a person of great value. I demand that the Office of Historiography is informed of this."

PW Peter Watson

1054: Crab •Recorded by Chinese astronomers as “guest star” •May have been recorded by Chaco Indians in New • X-rays (in blue) Mexico • + Optical 4 a.m. Tuesday 7th May 1054 • Tangled Would have been as bright as the appearance due to New moon trapped magnetic field Moon

Crab

Peter Watson Peter Watson •Shock wave blows off outer layer of star at What happens to a star when 1/10 speed of light it goes supernova?

•Large star runs out of fuel •Collapses and heats up

•Outer part explodes out,

•Core gets compressed to neutron star or black hole

Peter Watson Peter Watson

•Most recent close one was SN1987a Surprisingly… •Must have blown up earlier, leaving ring of • Most (98%) of the material, now illuminated by new shock energy doesn’t come wave out as light… • It’s neutrinos • As the matter falls in, the nu’s stream out!

Image credit: TeraScale Supernova Initiative.

Peter Watson Peter Watson

Which we can •We would like to catch supernovae before see here… they explode: here are 3 possibilities

Eta Carinae blew off a lot of material 150 years ago: probably pre-collapse now

Credit: J. Morse (U. Colorado), K. Davidson (U. Minnesota) et al., WFPC2, HST, NASA

Peter Watson Peter Watson •The Crescent Nebula is a shell of gas surrounding a •NGC 3603: can see formation of stars very hot and unstable central star WR 136 •contains Sher 25 surrounded by rings: • Should undergo a supernova explosion in next proably pre-collapse million years.

Peter Watson Peter Watson

•Nova: stars that repeatedly have minor explosions Might look like this

•Always a close binary •material flows from one star to companion Mark A. Garlick (Space-art.co.uk) •triggers explosion

Peter Watson Peter Watson

•V838 Monocerotis: Not What happens to a star after a nova, since star did not lose material, it goes supernova? instead went to M~ -7 (brightest star in •Large star runs out of fuel galaxy) by expanding and cooling very fast •Collapses and heats up

lit up dust from • Outer part explodes out, previous explosions • •Core gets compressed to neutron star or black hole

Peter Watson Peter Watson • Pulsars • accidentally observed (1968) by Jocelyn Bell etc. Best known is Crab. • Very regular radio pulses Known to be • period of 2 ms up to 4 s supernova remnant from • Note that height of pulse is very irregular in 1054 Pulsar at centre has period of ~1/30 s

Peter Watson Peter Watson

And you can even listen to Magnetars: Vicki Kaspi McGill them

• This is Vela

• And this is PSR 0329+54

Period of Crab measured to be 0.03308471603 s (i.e. stable to 1 part in billion) • Magnetic field is ~ 1 billion x strength of MRI magnet

Peter Watson Peter Watson

•This shows how the X-ray pulses move Double Pulsar through the nebula •

Peter Watson Peter Watson •Charged particles travel along magnetic What pulses? field,

• Now known to be neutron star: predicted by • can only escape from poles of neutron star. Oppenheimer (yes, that one) in 1935. •Hence "lighthouse"mechanism: we only • Density ~ atomic nucleus: dime would weigh “see” pulsar when mag. pole points towards 2000,000,000 tons! us

Peter Watson Peter Watson

Do we see all the pulsars? This is how the Fermi satellite

• No, because they would have to be oriented sees the sky, in gamma-rays so that they point towards us • Neutron Star forms from supernova, Period ~1/1000 s • spins down • magnetic field will weaken • Disappear after 100,000 years

Peter Watson Peter Watson

Gamma-rays have huge energies SS433 • And some things are just weird! • Crab? • A cosmic lawn sprinkler • OK: old supernova Geminga • jets come out at 1/5 of speed of light, but Vela? • Crab are made of cold hydrogen gas! • OK: old supernova • Geminga? • Huh? Second brightest object in γ-rays, almost invisible as a ordinary star • Turns out to be very old neutron star

Peter Watson Peter Watson KIC 8462852 or WTF star ("Where's Why? The Flux?")

• Produces 20% change in • Huge planet? output over a matter of a few days • Alien megastructures?

• Black Hole?

• Dark Star?

• Huge cloud of comets?

Alien megastructures A Jupiter-sized planet would cause a 1% drop in light on a regular basis

Comets?

But it’s also been dimming slowly anyway

Peter Watson

Black Holes Einstein was right: Astronomers • Invented by .....? confirm key theory on black holes Daily Express • Einstein!!!!!!!!! Historic First Images of a Black Hole Show Einstein Was Right (Again) Space.com

Peter Watson Unfortunately Einstein predicted The essential result of this black holes did not exist! investigation is a clear understanding as to why the "Schwarzschild singularities" do not exist in physical reality. …………… The "Schwarzschild singularity" does not appear for the reason that matter cannot be concentrated arbitrarily. And this is due to the fact that otherwise the constituting particles would reach the velocity of light.

PW PW

Black Holes Black Holes • Invented by .....? • Invented by .....? • Einstein • Einstein • Hawking!!!!!!!!!!! • Hawking • Well, actually he didn’t: first paper he wrote was in • John Wheeler 1971 (and first interesting paper was 1974!) Wheeler first used the term in a talk he gave in 1967. He understood that in reality they would be small and dense, with the implication that they might be observable.

Peter Watson Peter Watson

Black Holes • Invented by .....? • Einstein Black • Invented by .....? • Hawking? Holes • Einstein • John Wheeler? • Hawking • Karl Schwarzchild? • John Wheeler • Well, actually, John Michell, rector of Thornhill Church in Yorkshire • Karl Schwarzchild? • geologist?philosopher? astronomer? Seismologist? • Polymath. No, but he was the first person to presented his ideas on “dark stars” to the Royal solve Einstein’s equations for one • Society in London in 1783. Peter Watson Peter Watson •A particle will •However we can interpret this differently: what escape from the radius would the earth have for a given escape earth if it has velocity? positive energy •In particular, if the escape velocity is the speed of •At the earth's light c, nothing can escape. surface, “escape velocity” is 11 •If the earth was 8 mm in radius, it would be a km/s Black hole

•This is the Schwarzchild radius: roughly the black hole radius

Peter Watson Peter Watson

So what is a black hole like? • What is a straight line? • It warps space (and time) round it

So planets are actually moving in "straight" lines in a curved space... Did you think a laser beam was straight? • "Lenses extend unwish through curving wherewhon till unwish returns on its unself" e.e.cummings

Peter Watson Peter Watson

•Stuff falling in will become very hot and produce X-rays •One way to see a black hole: it’s black! •If we are really lucky....(or unlucky) as a gap •So want binary star, one invisible but heavy, producing in the sky lots of X-rays First candidate is Cygnus X-1

Mass of primary star ~20Mo

Mass of invisible object M~9Mo Power output in X-rays is 10,000 x total power output by Too Close to a Black Hole Credit & Copyright: Robert Nemiroff (MTU)< sun!

Peter Watson Peter Watson Note Stephen Hawking’s Why Einstein was wrong: BH’s are formed explosively main claim to fame • He bet Kip Thorne a year’s subscription to Penthouse that Cyg X-1 was NOT a BH Supernova- Black Hole formation animation from Chandra

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•Then moving BH’s will produce a wave in space •Black Hole merger: The Caltech/Cornell SXS Collaboration •

Peter Watson Peter Watson

•And this is maybe where it is happening now: •and these will radiate gravitational waves •Two galaxies have collided and the black holes seem to be coalescing

3C75 X-rays from Chandra

Peter Watson Peter Watson •Which we might be able to pick up on earth One of the first attempts as gravitational waves

• Giorgio Pappini at •This is LIGO: twin detectors in Louisiana University of Regina and Washington • Build cold quartz- crystal detector

U of R Peter Watson

Peter Watson Peter Watson

and they found a second Nobel Prize in Physics one! • Which you can listen to! 2017

Kip Thorne Rainer Weiss Barry Barish

Peter Watson Peter Watson •Vary short (often less than 1/100 s!) intense Gamma-ray bursters bursts of γ-rays.

Found accidentally Don’t repeat, don’t come from any known object by Vela satellite • (designed to look for γ's from nuclear explosions). Seem to be massive explosions in very distant galaxies

Peter Watson Peter Watson

• Common (about 1/week) Scattered all over the sky • Extremely energetic (energy ~ all stars in known universe concentrated into few seconds) • No two the same!

PW PW

All the Gold you dreamed of…. If they were local they would map out the Milky Way

But wherefrom???????? did it come

Wikipedia A long story…… Mostly science has no dramatic moments: e.g. DNA

• isolated (Friderich Miescher) ~1885 • nucleotides identified Phoebus Levene ~ 1919 • "giant hereditary molecule" (Koltsov) ~ 1927 • Genetic material in T2 Phage (Hershey) ~1953 • X-ray diffraction show helix (Wilkins & Franklin) ~ 1953

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====> Central Dogma: GALILEO (1564-1642) Watson & Crick 1953

• Lived in Pisa • DNA is two interlocked coils of amino-acids

PW Peter Watson

• Exploited (but didn’t invent) telescope • Moons of Jupiter: Jan 7/8th 1608

Peter Watson Peter Watson Galileo shows BOTH This is his original notebook Prolemy and Copernicus are • The earth is not the centre of the universe, but more things than the sun can be the centre of orbits • Need Newton to understand this

PW Peter Watson

Where does everything come from? To make heavy nuclei, just add protons & neutrons

PW

•Type 1a Supernova To start with, fusing light •Very rare (1/galaxy/century), very bright and they are nuclei to make heavier all the same nuclei GIVES us energy •This is one in Centaurus A

Long straight bit of light curve is decay • But after Iron, we need to add energy to of Co56 to Iron create new nuclei

PW Peter Watson Where does everything come from? Cassiopeia A Supernova remnant from about 350 years ago

Created in Big Bang Small Stars neutron star Large stars & supernova

silicon red, sulphur yellow calcium green iron purple X-rays blue ????????????????????????????

Image Credit: NASA, CXC, SAO

Confused? An executive summary August 17, 2017, 12∶41:04 UTC

• Gravitational Wave Signal seen • We don’t know where the heavy elements come from • We don’t know what gamma-ray bursters (GRB’s) are • We don’t know if gravitational waves travel at the speed of light It all comes • We’ve never seen two stars collide! together!

PW PW

Where is it?

1.7 s later, Gamma- ray pulse

PW PW Email your friends… Dark-Energy Camera in Chile finds it first!

GW+EM Observatories Map Approximately 70 light-based observatories that detected the gravitational-wave event called GW170817. PW

And that’s how the gold in your wedding ring was made! NGC 4993: The Galactic Home of an Historic Explosion Image Credit: NASA & ESA

In Hydra

PW

Wedding ring, What it looked like.. Byzantium, 7th c. AD, nielloed gold

Jastrow, Wikimedia

Approximately 10 Earth Masses of Gold and Platinum! ~10,000,000,000,000,000, 000,000,000 tonnes

NASA So in one day… 6000 people round the world • Verified Einstein (gravitational waves exist and travel at the speed of light)

• Explained GRB’s as colliding neutron stars

• Observed a “kilonova” for the first time

• Showed us how elements are made • A good day for all of us!