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Piramon Kumnurdmanee
University of California, Santa Cruz
What are Type Ia supernovae?
What are Type Ia supernovae?
Type Ia supernovae are thermonuclear explosions of carbon-oxygen white dwarfs in binary systems. This occurs when a white dwarf accumulates mass from a companion star, eventually reaching a critical limit (~1.44 solar masses) and igniting a runaway thermonuclear reaction.
Credit: R.N. Bailey
Type Ia Supernovae: Thermonuclear Runaway Explosions of White Dwarfs
Type Ia Supernovae: Thermonuclear Runaway Explosions of White Dwarfs
Credit: ESO
Credit: David Wakeham
Electron Degeneracy
Electron Degeneracy
Stars with less than 8 times the mass of the Sun end their lives as white dwarfs.
Inside a white dwarf, electrons are packed so tightly that they can’t be squeezed any closer, creating electron degeneracy pressure, a quantum force that resists gravitational collapse.
Chandrasekhar mass: the maximum mass a white dwarf can have before collapsing — about 1.44 solar masses.
Why Study Type Ia Supernova?
Why Study Type Ia Supernova?
Standardizable Candles: Relatively uniform peak brightness:
Measure cosmological distance
Map the expansion of the Universe.
Main Iron Producers:
Ni-56 -> Co-56 -> Fe-56: the decay produces gamma rays that power and shape the brightness evolution of the supernova light curve.
What causes a white dwarf to explode?
What causes a white dwarf to explode?
Single Degenerate
Single Degenerate
A white dwarf accretes mass from a non-degenerate star
Double Degenerate
Double Degenerate
Merger of binary white dwarf
What and where is SN2021qvv?
What and where is SN2021qvv?
SN2021qvv is a sub-luminous SN Ia located in NGC 4442, a barred lenticular galaxy in the Virgo Galaxy Cluster
This plot shows that the light curve of SN 2021qvv is dimmer than that of a typical SN Ia
Virgo Galaxy Cluster is the nearest galaxy cluster to us. With its dense stellar populations, the SN Ia population is also relatively dense.
Did this supernova happen in a globular cluster?
Did this supernova happen in a globular cluster?
Globular Cluster
Globular Cluster
A tightly bound, gravitationally stable system of stars
Contains hundreds of thousands to millions of stars
Stars were born together from the same molecular cloud, making them roughly the same age
Let's search for the supernova progenitor!
Let's search for the supernova progenitor!
Hubble Space Telescope
Hubble Space Telescope
Centroiding
To determine the supernova’s exact location, we calculate its centroid in the post-explosion HST image.
Astrometric Alignment and Pre-Explosion Localization
Using pre-explosion ACS/F475W and ACS/F850LP images, we aligned the frames with the post-explosion HST image by matching common stars (purple labels). This allowed us to transform the supernova’s position onto the pre-explosion frames. The yellow circle marks the expected location of SN2021qvv in both filters.
No Detection in Pre-Explosion Images
The zoom-in reveals no visible source at the expected progenitor location in either the ACS/F475W or ACS/F850LP image.
Determine the Detection Limit
Determine the Detection Limit
Progenitor Constraints
Progenitor Constraints
Reference
Reference
Graur, O., Gonzalez, E. P., Burke, J., et al. 2023, MNRAS, 526, 2977
Jord´an A., et al., 2007, ApJS, 171, 101
Li, W., Bloom, J. S., Podsiadlowski, P., et al. 2011, Natur, 480, 348
Wang, B., & Han, Z. 2012, NewAR, 56, 122
Zheng-Wei Liu et al 2023 Res. Astron. Astrophys. 23 082001
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