1. Novae and supernovae Szydagis04.08.2015 1/13 Artistic representation of a supernova in progress, from http://www.chi natopix.com The guest stars

2. What is a nova? Latin for ‘new.’ Referring to a new star appearing in night sky Latin for ‘new.’ Referring to a new star appearing in night sky A white dwarf star accretes hydrogen from a massive partner A white dwarf star accretes hydrogen from a massive partner Fresh outside layer of hydrogen gets compressed under the gravitational pressure (a function of depth) of its own mass, heating until fusion can begin anew in the star Fresh outside layer of hydrogen gets compressed under the gravitational pressure (a function of depth) of its own mass, heating until fusion can begin anew in the star However, a white dwarf does not have the correct structure and mass to maintain hydrostatic equilibrium However, a white dwarf does not have the correct structure and mass to maintain hydrostatic equilibrium A thermonuclear blast occurs, akin to a giant hydrogen bomb in space, causing a brightening. Dwarf survives, cycle repeats A thermonuclear blast occurs, akin to a giant hydrogen bomb in space, causing a brightening. Dwarf survives, cycle repeats 2/13

3. 3/13 An artist’s impression of a star system responsible for a nova. Photograph: David A. Hardy/www.astroart.org//PA

4. 4/13 Image Credit: NASA, ESA, and A. Feild (STScI); vectorisation by chris 論 - http://hubblesite.org/newscen ter/archive/releases/star/supe rnova/2004/34/image/d/ Covered basics (last steps) already Covered basics (last steps) already In context of standard candle on cosmic distance ladder (Lecture 5) In context of standard candle on cosmic distance ladder (Lecture 5) Main difference from a nova: brighter explosion, because star does *not* survive Main difference from a nova: brighter explosion, because star does *not* survive Replaced with a black hole Replaced with a black hole Caused by any matter accruing Caused by any matter accruing

5. An Alternative Model 5/13 Image: GSFC / Dana Berry. A two white-dwarf merger (supernova classification does not refer to origins, about which we must theorize)

6. Type Ib, Ic, II Supernovae We already covered these in the last lecture, but without naming them. These are caused by a red SUPERgiant onion collapse and fireball, after iron core maximum scrunch We already covered these in the last lecture, but without naming them. These are caused by a red SUPERgiant onion collapse and fireball, after iron core maximum scrunch Distinguishable from Type 1a by the lack of single-ionized silicon absorption line. 1b possesses lines of helium that 1c lacks. Absorption & emission spectra tell us elements Distinguishable from Type 1a by the lack of single-ionized silicon absorption line. 1b possesses lines of helium that 1c lacks. Absorption & emission spectra tell us elements Typical death of a massive star, leaving a neutron star or a black hole behind. (By contrast, red giant leaves behind a white dwarf, and a planetary nebula without supernova) Typical death of a massive star, leaving a neutron star or a black hole behind. (By contrast, red giant leaves behind a white dwarf, and a planetary nebula without supernova) Type II (many subtypes) distinguishable by the presence of hydrogen, but same old, while “hypernovae” possibly caused by influx of matter into black hole, or hole merger Type II (many subtypes) distinguishable by the presence of hydrogen, but same old, while “hypernovae” possibly caused by influx of matter into black hole, or hole merger 6/13 Minkowski-Zwicky Classification Scheme, by absorption lines

7. Famous Supernovae Type II July 4, 1054, observed by the Chinese, that led to the creation of the Crab Nebula and a pulsar Type II July 4, 1054, observed by the Chinese, that led to the creation of the Crab Nebula and a pulsar 1604 Type Ia (in retrospect) observed by Kepler 1604 Type Ia (in retrospect) observed by Kepler Type II in 1987(A), whose neutrinos were detected by underground experiments in labs across world Type II in 1987(A), whose neutrinos were detected by underground experiments in labs across world Occurred in Tarantula Nebula, in neighboring LMC Occurred in Tarantula Nebula, in neighboring LMC A supernova occurs only once or twice per century per galaxy is the rule of thumb. Can not predict A supernova occurs only once or twice per century per galaxy is the rule of thumb. Can not predict We can see the light from one that is even billions of light years away, especially if Type Ia. But neutrinos from close by (reduced flux plus harder to detect) We can see the light from one that is even billions of light years away, especially if Type Ia. But neutrinos from close by (reduced flux plus harder to detect) 7/13

8. Progression 8/13 [NASA/HST, Z. Levay, B. Preston] The rings seen around SN1987A by the Hubble Space Telescope were a big surprise and their origin is still a mystery. We suspect that the progenitor star was a binary star system that merged some 20,000 years before it exploded, ejecting the rings during the merger. The blast wave from the supernova explosion is just now beginning to hit the ring, causing a bright spot to appear. During the next ten years, the ring should become several hundred times brighter than it is today, giving us an opportunity to understand the mechanism by which the rings were ejected. [The video at the lower right.] http://astronomy.nmsu.edu/geas/lectures/lecture25/slide02.html

9. Review of Dwarfs and Giants We have covered knowledge you require to answer We have covered knowledge you require to answer List every type of dwarf star and giant star you can come up with, and the properties or key features of each category (usually denoted by color) List every type of dwarf star and giant star you can come up with, and the properties or key features of each category (usually denoted by color) Half of you, start with dwarfs and other half giants Half of you, start with dwarfs and other half giants 9/13

10. Origins of the Elements Big Bang Nucleosynthesis (BBN) gives us a lots of hydrogen, some helium, and a smattering of the other lightest elements Big Bang Nucleosynthesis (BBN) gives us a lots of hydrogen, some helium, and a smattering of the other lightest elements The complex cores of red giant and supergiant stars give us many of the intermediate-mass elements, up through iron, via nuclear fusion. Hydrogen, helium, C, O, Ne, Mg, Si, S, Ni The complex cores of red giant and supergiant stars give us many of the intermediate-mass elements, up through iron, via nuclear fusion. Hydrogen, helium, C, O, Ne, Mg, Si, S, Ni A supernova blast gives us the rest of the elements, stable and radioactive, filling up the entire periodic table of naturally occurring elements all the way up through uranium (Z = 92) A supernova blast gives us the rest of the elements, stable and radioactive, filling up the entire periodic table of naturally occurring elements all the way up through uranium (Z = 92) R-process and s-process: we are all made up of star material! R-process and s-process: we are all made up of star material! 10/13

11. A Luminous Red Nova? A merger of two stars A merger of two stars Typically main sequence though, not white dwarfs Typically main sequence though, not white dwarfs Between a white dwarf nova and a supernova, which can outshine a galaxy, in terms of brightness Between a white dwarf nova and a supernova, which can outshine a galaxy, in terms of brightness As with other stellar phenomena, sustain a certain characteristic brightness pattern As with other stellar phenomena, sustain a certain characteristic brightness pattern Characteristically red and infrared Characteristically red and infrared Recent discovery: first announced only in 2007 Recent discovery: first announced only in 2007 Why this color? Hmm Why this color? Hmm 11/13

12. More to World Than Lights Gamma ray bursts (GRBs) detectable by Fermi-LAT Gamma ray bursts (GRBs) detectable by Fermi-LAT Recall Lecture 17 Particles From Space, and AGNs Recall Lecture 17 Particles From Space, and AGNs X-ray pulsars, detected by Chandra observatory X-ray pulsars, detected by Chandra observatory Same old story: infalling mass from partner again Same old story: infalling mass from partner again Astrophysical masers (microwave laser-equivalents) Astrophysical masers (microwave laser-equivalents) Molecular clouds, atmospheres, even interstellar space Molecular clouds, atmospheres, even interstellar space All the combinations of binary, trinary, etc. stars All the combinations of binary, trinary, etc. stars Stellar winds eject mass at high speeds due to either high temperature or to direct radiation pressure Stellar winds eject mass at high speeds due to either high temperature or to direct radiation pressure 12/13

13. Homework Read about stellar remnants from star collapse for Friday. A bit more reading than usual, since the subject is so rich, vast Read about stellar remnants from star collapse for Friday. A bit more reading than usual, since the subject is so rich, vast First: white dwarfs and neutron stars (Kip Thorne!) First: white dwarfs and neutron stars (Kip Thorne!) Second: black holes (Stephen Hawking) Second: black holes (Stephen Hawking) Third: A Black Hole Mystery Wrapped in a Firewall Paradox (NYT) http://www.nytimes.com/2013/08/13/science/space/a-black-hole- mystery-wrapped-in-a-firewall-paradox.html?_r=0 Third: A Black Hole Mystery Wrapped in a Firewall Paradox (NYT) http://www.nytimes.com/2013/08/13/science/space/a-black-hole- mystery-wrapped-in-a-firewall-paradox.html?_r=0 http://www.nytimes.com/2013/08/13/science/space/a-black-hole- mystery-wrapped-in-a-firewall-paradox.html?_r=0 http://www.nytimes.com/2013/08/13/science/space/a-black-hole- mystery-wrapped-in-a-firewall-paradox.html?_r=0 13/13 Homework On the web, on our site