Photometry of Type Ia Supernovae: Search for the Second
Parameter Date: May 15, 2009 Author: Kevin Perot Advisor: Dr. Baron
Slide 2 Outline Motivation Distance indicators Background Supernova
types Type Ia supernovae Why theyre cool Why they blow up How they
blow up How we use them My research What Ive been doing My results
Remnant of Tychos Nova, a type Ia supernova observed by Tycho Brahe
in 1572. Slide 3 radar parallax main-sequence fitting cepheids
Tully-Fisher relation type Ia supernovae solar system nearby stars
Milky Way nearby galaxies galaxy clusters Hubbles Law Distance
Indicators Measuring distances in astronomy requires some
creativity Cosmic distance ladder: Why do we care? Cosmological
parameters Composition of early galaxies Slide 4 Supernova Types
Classified based on spectral lines Type II:Strong H Type Ia:Strong
Si Essentially no H Type Ib:Strong He Essentially no H or Si Type
Ic:Essentially no H, Si, or He H He S Si Fe Type Ia Type Ic Type Ib
Type II Slide 5 Type Ia Supernovae: Distance Indicators I What
makes type Ia supernovae good distance indicators? Very common
Average-mass progenitor Very bright Absolute magnitude: -19.3
Outshines host galaxy Very consistent Peak magnitude variation:
~0.3 Much of this can be corrected for SN 1994D, discovered in the
galaxy NGC 4526. This galaxy is in the Virgo cluster, about 60
million light years away. Slide 6 Type Ia Supernovae: What Causes
Them? Accretion model Two stars are in a binary system First, the
larger one evolves to a white dwarf Then, the smaller one evolves
to a red giant Matter spills from red giant to white dwarf When the
dwarf reaches the Chandrasekhar limit (about 1.4 solar masses), it
explodes Collision model Two white dwarfs merge Less likely May
explain anomalously massive Supernovae Merging white dwarfs
emitting gravitational waves White dwarf accreting matter from
giant companion Slide 7 Slide 8 Type Ia Supernovae: Explosion
Mechanism Fusion reignites as mass approaches Chandrasekhar limit
Deflagration Leaves some material unburned Detonation Not enough
intermediate-mass material produced Delayed Detonation Begins as a
subsonic deflagration, allowing the star to pre-expand Deflagration
turns into a detonation, burning the remaining material Most of the
C and O burned to 56 Ni, with some S and Si Model of a type Ia
supernova. The blue surface shows deflagration; the white surface
shows detonation. Slide 9 Type Ia Supernovae: Energetics All energy
released during burning goes into kinetic energy Unbinds the star
Depends primarily on C/O ratio The light we see comes from decay of
56 Ni Primary product of burning Amount of 56 Ni primarily depends
on central density Decay heats up supernova remnant Remnant
initially opaque, but becomes transparent after a few days White
Dwarf Kinetic Energy Star Unbound 56 Ni Decay Light Emission Slide
10 Type Ia Supernovae: Distance Indicators II Brightness varies
slightly Different amounts of 56 Ni Brightness related to decline
rate Brighter supernovae decline more slowly Brighter supernovae
are hotter, and thus more opaque Stretch method May be more
variations we can account for Slide 11 Light curves in blue and
visible bands Brightness Time (days) My Project Learn to use IDL
Analyze supernova data to look for more parameters Data from
Carnegie Supernova Project (CSP) Light curves from 17 supernovae
Very similar observing parameters Slide 12 High-mass progenitor
Theoretical Model Model by Peter Hflich Variations in progenitor
mass cause variations along the light curve Specifically looking
for the pattern of a high-mass progenitor Most identifiable pattern
Slide 13 Results Several light curves fit this pattern Evidence of
a range of progenitor masses between 5 and 7 solar masses Decline
rate related to progenitor mass Slide 14 Questions? Artists
conception of type Ia supernova before the explosion and 20 days
after Slide 15 Image sources Outline
http://upload.wikimedia.org/wikipedia/c
ommons/a/ac/Main_tycho_remnant_ful l.jpg Supernova Types
http://panisse.lbl.gov/~dnkasen/tutorial /graphics/sn_types.jpg
Distance Indicators http://www.daviddarling.info/images/di
stance_ladder.jpg Type Ia Supernovae: Distance Indicators I
http://www.cfa.harvard.edu/supernova/ /HighZ.html Type Ia
Supernovae: What Causes Them? http://www.nscl.msu.edu/files/images/
1301_800.preview.png http://images.astronet.ru/pubd/2005/06
/02/0001206140/wd_cxc_c33.jpghttp://images.astronet.ru/pubd/2005/06
/02/0001206140/wd_cxc_c33.jpg Slideshow
http://www.pha.jhu.edu/~bfalck/Iaprog
enitor.jpghttp://www.pha.jhu.edu/~bfalck/Iaprog enitor.jpg Type Ia
Supernovae: Explosion Mechanism
http://images.iop.org/objects/physicsw
eb/world/21/12/35/PWfea6_12-08.jpg Type Ia Supernovae: Distance
Indicators II http://www.lbl.gov/Science-
Articles/Archive/sabl/2005/October/str
etch_correction.jpghttp://www.lbl.gov/Science-
Articles/Archive/sabl/2005/October/str etch_correction.jpg
Questions? http://www.sciencedaily.com/images/2
007/07/070713234636-large.jpghttp://www.sciencedaily.com/images/2
007/07/070713234636-large.jpg
