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Discussion for the Time Domain and Multi-Messenger Astrophysics Group (1.3)
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How and where are the elements created? #4

Open jeffcooke opened 4 months ago

cwjames1983 commented 4 months ago

@jeffcooke Can you flesh out the science behind this a bit more? I recall SNe, kilonovae, Adelle mentioned x-ray bursts I believe... anything else?

jeffcooke commented 4 months ago

Sure. It's largely the obvious, but has multiple additional aspects to leverage science (theory and observation), infrastructure, roboticisation of facilities, data handing, processing and analysis, facility coordination, etc. behind it (touched on below). Also, the public and government official appeal, and addressing something tangible.

The science starts at where did all the elements heavier than helium come from? How were they made? Where were they made? How did they impact the generations of stars (populations I, II, and III), the formation of structure - galaxies, star systems, and planets? For example, there would be no planets, Earth, or us if there weren't transients.

Although some elements are created in the cores of stars, it takes supernovae to eject them into the Universe. There are kilonovae and the heaviest elements. And there are newer classes, e.g., FBOTs, etc.

This question enables work in nucleosynthesis, interacting star systems (which there is a lot of work on in AU), transients of all types (ditto), as each contribute differently. It also enables infrastructure progress, as transients need to be detected while they're bursting to get the necessary spectra.

This needs to be done fast, creating serious challenges for technology, data compression, transfer, processing, identification from the millions of sources in the images, ML code, etc. In addition, it requires instrumentation to facilitate searches and spectroscopy and facility coordination across Australia (and the world).

Moreover, the faster you can do this, the more you learn, as much of the nucleosynthesis occurs early (e.g., 'flash' spectroscopy, fast-evolving events, etc.). Finally, it requires a broad range of wavelengths, as some atomic transitions are best (or only) detected in the X-ray, UV, optical or infrared, or inferred from other wavelength data. And, of course, it takes all wavelengths and all messengers to find the sources, depending on type.

From: cwjames1983 @.> Sent: Thursday, 22 February 2024 5:05 PM To: ethrane/transients @.> Cc: jeffcooke @.>; Mention @.> Subject: Re: [ethrane/transients] How and where are the elements created? (Issue #4)

@jeffcookehttps://github.com/jeffcooke Can you flesh out the science behind this a bit more? I recall SNe, kilonovae, Adelle mentioned x-ray bursts I believe... anything else?

— Reply to this email directly, view it on GitHubhttps://github.com/ethrane/transients/issues/4#issuecomment-1958765524, or unsubscribehttps://github.com/notifications/unsubscribe-auth/AC5TFNAZNZFWI337MV33BRDYU3N4DAVCNFSM6AAAAABDQ6GV7WVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSNJYG43DKNJSGQ. You are receiving this because you were mentioned.Message ID: @.***>

ethrane commented 4 months ago

I think this is good science, but I think it fits more naturally under the purview of Group 1.2 Stars, Planets, and the Galaxy. They will push this forward with less of a transient focus, looking at the production of elements over cosmic time. I think we are best served by asking them to highlight the role of transients in that bigger program. There are other questions where time-domain astronomy plays a more central role, that I think are best for us to focus on.

jeffcooke commented 4 months ago

Hi Eric,

From your email, it appears that I wasn't sufficiently clear in the question. The question is "How and where are the elements (actually) created?. I'm not sure how stars, planets and the Galaxy would address this. They can trace the chemical enrichment over time (which would be more extragalactic astronomy, however) and, perhaps, how the elements in molecular clouds cool, collapse and form stars and stellar systems, but not 'how and where are elements (actually) created'. If they 'look at the production of elements over time', they're looking at the transient rate overt time and the elements each of the sources (transients) produce over time. But that does not address the question.

This question, as posed, is 100% transients and is (and has been) a core question of transient science. As this may not be an area of expertise for everyone, the image below may help understand what I mean. Nearly all elements are created in novae, supernovae (different types produce different abundances), planetary nebulae, kilonovae, etc. It takes the conditions created by these transients for the necessary r-processes to make them and observations of transients to detect their nucleosynthetic yields to answer 'how and where they are created'.

The question challenges transient observations and coordination of transient detection and follow up (i.e., fast detection to get spectra). Australia does this and needs to do it well in the next decade for Rubin (and other) transient follow up, especially as the world will look to Australia on how we handle this because, as the Earth turns, we are the first land mass to follow up Rubin and most of its 10 million transients. The question challenges Australian-built instruments, facilities and, of course, transient theory. For example, we don't know what empirically what elements kilonovae actually produce, how much of which type they produce, nor their contribution to the whole. Nor do we know the specific ratios of elements various types of supernovae produce, how, where, and when they're produced, nor each of the supernova rates sufficiently well to know their contributions over time. This is a whole industry.

Thus, the question, as posed, fits more naturally under transients than stars, planets, and the Galaxy.

[cid:1f05e672-3a9c-43b9-8c6a-fa75e4650ba1]

From: ethrane @.> Sent: Monday, 26 February 2024 1:19 PM To: ethrane/transients @.> Cc: jeffcooke @.>; Mention @.> Subject: Re: [ethrane/transients] How and where are the elements created? (Issue #4)

I think this is good science, but I think it fits more naturally under the purview of Group 1.2 Stars, Planets, and the Galaxy. They will push this forward with less of a transient focus, looking at the production of elements over cosmic time. I think we are best served by asking them to highlight the role of transients in that bigger program. There are other questions where time-domain astronomy plays a more central role, that I think are best for us to focus on.

— Reply to this email directly, view it on GitHubhttps://github.com/ethrane/transients/issues/4#issuecomment-1963205060, or unsubscribehttps://github.com/notifications/unsubscribe-auth/AC5TFNAP2X5VX2CGSQJEPTTYVPWLJAVCNFSM6AAAAABDQ6GV7WVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSNRTGIYDKMBWGA. You are receiving this because you were mentioned.Message ID: @.***>

ethrane commented 4 months ago

Hey, @jeffcooke. A lot of people who don't do transient astronomy are interested in chemical evolution of stars. Many of these stars eventually explode and disperse the elements through the Universe (and as you note, the explosions themselves make new elements), but the answer to this question for many astronomers is "in stars" (before they explode). In other words, the production of heavy elements in transient events is, in the scheme of things, just a piece of a big field. I guess my point is that: we can support this, but we should understand that the transient part may end up being just one plank in a broader program.

jeffcooke commented 4 months ago

Hi Eric,

Understood. My point is that very few elements are made in stars. That's at the heart of the question. Only as they explode are most of them made. And it's studying these transients is where we learn all this.

If it is one plank of a broader program, it is the main, largest plank. Keep in mind that the chemical evolution of stars is only with a few elements (and their dredge up etc). If you're talking about chemical evolution of populations of stars (Pop I, II, and III), now you're again into the production of the elements created by transients over cosmic time.

Hey, @jeffcookehttps://github.com/jeffcooke. A lot of people who don't do transient astronomy are interested in chemical evolution of stars. Many of these stars eventually explode and disperse the elements through the Universe (and as you note, the explosions themselves make new elements), but the answer to this question for many astronomers is "in stars" (before they explode). In other words, the production of heavy elements in transient events is, in the scheme of things, just a piece of a big field. I guess my point is that: we can support this, but we should understand that the transient part may end up being just one plank in a broader program.

— Reply to this email directly, view it on GitHubhttps://github.com/ethrane/transients/issues/4#issuecomment-1963318419, or unsubscribehttps://github.com/notifications/unsubscribe-auth/AC5TFNERZCRBIIRPHBPPZF3YVQIXZAVCNFSM6AAAAABDQ6GV7WVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSNRTGMYTQNBRHE. You are receiving this because you were mentioned.Message ID: @.***>