Scientists Observe Year-long Plateaus in Decline of Type Ia Supernova Light Curves

[gary]

Press release here :-
https://www.cfa.harvard.edu/news/2019-23

[PeterM]

Thanks for posting this Gary,

The supernova mentioned in the article (SN2012gc) was discovered by Greg Bock and was the 47th discovery for the BOSS team, discovery image below. The initial classification was a type II so something has changed along the way.
Goes to show (yet again) that amateurs like you and I can and do have an impact on the science of Astronomy and this may indeed come many years after the initial discovery.
Kudos indeed to Greg Bock!

[gary]

Hi Peter,

Thanks for the follow-up which is very much appreciated.

In fact when I first read the press release I had you and the BOSS team
in mind with the decision of re-posting it.

So it is absolutely wonderful to hear that the cited object was one that
Greg had discovered! That's fantastic!

Having said that, between you all having done such a splendid job
in discovering so many, perhaps statistically it shouldn't come as a
surprise at all. :)

It was the second last paragraph in the press release that really caught
my attention when they said, "What we’re seeing is in stark contrast to
what we’ve always believed about Type Ia supernovae and it's going to
impact the way we apply Type Ia light curves to cosmological models in
the future."

I am not sure if this is implying the discovery has slightly ruffled how
Type Ia's were being used as standard candles? As I understand it,
their peak luminosity was used for that metric, so perhaps you understand
better what the implications of the plateauing is in that regard?

[astroron]

Hi Gary,I just mentioned the same thing to Greg on FB what it might mean to the cosmological distance model.
Well done to Greg and all the team,just shows that amateurs can and do contribute to Science and Astronomy.
Cheers:thumbsup:

[PeterM]

Hmmm, a bit of detective work from Greg and I found that the actual science paper that refers to this research notes that the Supernova was infact SN2012cg discovered by LOSS ([Discoverer=Kandrashoff, Cenko et al. (LOSS) ). The original Harvard Smithsonian Center for Astrophysics press release had a typo noting SN2012gc. We have informed Harvard and as you will now see in Gary's link above this has now been corrected.
No cigar for Greg/BOSS on this one, but we did our bit in making sure the correct credit was acknowledged where due.
Again thanks to Gary for posting as it indeed shows there is still much science is finding out about Supernova.

[astroron]

Definitely.:)
You guys still do a great job:thumbsup:

[gary]

Hi Peter,

Thanks for the correction notice and though it transpires Greg didn't discover
this specific one, we know all the SN the BOSS team have discovered have
been the subject of professional scientific investigation.

Thanks also for the quote that appeared in your response on the
Standard Candle question but unfortunately got chopped when you
edited about the correction.

Perhaps the transition points as one comes off the plateaus are giving
astronomers further standard candle references. Prior to the discovery
perhaps they were reliant on just the peak intensity point.

[Greg Bock]

Well, as you can imagine, I was quite surprised and disappointed to find the typo in the Harvard article once I obtained a copy of the original paper.
However, have set the record straight, Harvard have changed the reference, but there may be more articles out there that won't be changed.
So, its back to the scope for me, and try to find some more worthwhile discoveries.....

[PeterM]

Ooops!


Abstract
The light curves of type Ia supernovae are routinely used to constrain cosmology models. Driven by radioactive decay of 56Ni, the light curves steadily decline over time, but after 150 d post-explosion the near-infrared portion is poorly characterized. We report a year-long plateau in the near-infrared light curve at 150–500 d, followed by a second decline phase accompanied by a possible appearance of [Fe I] emission lines. This near-infrared plateau contrasts sharply with type IIP plateaux and requires a new physical mechanism. We suggest a masking of the ‘near-infrared catastrophe’—a predicted, yet unobserved, sharp light-curve decline—by scattering of ultraviolet photons to longer wavelengths. The transition off the plateau could be due to a change in the dominant ionization state of the supernova ejecta. Our results help explain the complex radiative transfer processes that take place in type Ia supernovae and enhance their use as ‘standard candles’.