Welcome to Astronomy Podcast produced by Academia Sinica Institute of Astronomy and Astrophysics, I am Lauren Huang ~ So happy to have Dr. Daniel Harsono here with us today. Daniel is one of the guys who were awarded James Webb Space Telescope time, or, the other way to put it, the time allows you to make observation using this very powerful space telescope, acronym JWST. A telescope people have been waiting for for 20 years. Totally, three projects submitted from Taiwan got the green light, and Daniel leads one of them. After graduated from the UCLA in America, Daniel moved to Netherlands and obtained master and PhD degrees from the Leiden University. Hi Daniel, is it right that Leiden is a world leading school especially famous for the astronomy department?

Welcome to Astronomy Podcast produced by Academia Sinica Institute of Astronomy and Astrophysics, I am Lauren Huang ~ So happy to have Dr. Daniel Harsono here with us today. Daniel is one of the guys who were awarded James Web Space Telescope time, or, the other way to put it, the time allows you to make observation using this very powerful space telescope, acronym JWST. A telescope people have been waiting for for 20 years. Totally, three projects submitted from Taiwan got the green light, and Daniel leads one of them. After graduated from the UCLA in America, Daniel moved to Netherlands and obtained master and PhD degrees from the Leiden University. Hi Daniel, is it right that Leiden is a world leading school especially famous for its astronomy department?

Very famous in terms of history(s), yes. Yes a lot of famous astronomers are from Leiden, but they have very famous law faculty and also physics department.

Right, we are going to talk about, again, the JWST telescope. Last time we interviewed Sascha Ziggers about the same topic, would you please tell us again what is this telescope aims to do?

So JWST is James Webb Space Telescope it is the next generation optical or infrared of after Hubble Space Telescope. So Hubble Space Telescopes maps the sky in the optical domain that's the same wavelength that human eyes can see but the James Webb Space Telescope will focus mostly in the infrared so that's the regions where human eyes cannot see and by moving to the infrared you can see cooler objects so much younger and much more distant than what Hubble can see. So with the James Webb Space Telescope, for example, you can study more of the first stars and the very distant universe and then also because James Webb is very sensitive you can try to see the dust features that are present in the infrared.

Right. By the way, which subjects were you best at? Math? Physics? Chemistry?

I think from my background it was mostly mathematics so yes it was mostly mathematics

And that helps a lot in doing astronomical research?

For astronomy what the interest me the most was black holes and neutron stars so that was the reason why i went to UCLA but in the end I did not study them. But yes! Math is helped a lot but i think in the end i was much better at doing programming rather than pure mathematics.

You've won the JWST observation time at the first cycle right? are you doing a "mapping" related project?

Yeah that's correct. Our proposal is to map so-called jet launching region. This is the region where young protostars try to release a lot of its energy so when a young star born a lot of material is ejected from the young star and this is in form of a jet or an outlaw and previous instruments have difficulties in mapping this hot region near the young star where the material is launched so ALMA does not actually gives you a really full picture of the jet launching region. So this is where uh JWST will try to solve that problem.

Why do you think your proposal got selected? can you guess?

I think I'll try to speculate here but what we're trying to do with the project is that we have a lot of data from ALMA from HST also follow-ups high spectral resolution spectra in the optical and near infrared where we know all the molecules that are present in that region and what JWST can do is the mapping so we can try to see where those molecules are located. So now we just know that what the line profile or how that the emission is looks like in terms of velocity space does it go fast or slow. In addition, by mapping it you know where it is but especially from the center, so then you know where it is fast whether it's close to the center or it's actually fast further away. So it's the mapping is from the IFU instrument so the NIRSPEC (it is the name of the instrument) has an IFU, an Integral Field Unit um yeah so by in that case what you get is spatially and spectrally resolved data so you get the spectral cube so you know your xy and spatially resolved down to 0.1 arc seconds so that's roughly 14 au or so. But then you also have the third component which is the velocity so you can you have the full data set.

All right! So that will help us understand the region much better.

Yep, right.

I know you are also involved in that water review recently published by Leiden university right, so can you tell us about the "Water Journey" story that group of astronomers were working on?

Yeah um so the Herschel (Telescope) this uh the Water Review is based on the previous far infrared space telescope which is the Herschel Space Observatory, it is no longer active. Um so what Herschel can do is that it can it was targeting a lot of the water emissions -- the spectra of the fingerprint of water -- that is actually in space. The main aim of the program uh the Herschel Program that's called WISH so Water and Star forming regions with Herschel, to map and to detect water emission from early stages of star formation down to the later stage of planet the late stage of star and planet formation so what you want to know is how water is being transported from the molecular cloud where stars are born down to the region where the planets are actually being formed so with Herschel it is the only way that can probe this really cold water emission that you cannot do from the ground. So we need another telescope like Herschel in order to do this better, and there's no other plan for the next Herschel in the near future. So the Water Review tells you a lot of the improvement over the last time that we know how the water is being transported during star and planet formation.

Unfortunately the biggest surprise was that water is not very abundant than previously thought.

Oh? it is not?

Right, the previous infrared telescope that was Spitzer (Telescope). Spitzer probe not the water – well -- it probes the water emission from the very inner regions of the planet forming disks and it also probed the ice features so dust grains have ices on them and spitzer revealed that water is the most abundant in the ice in the solid form that is consistent with the theory. In that case then when this a lot of water ice is being transported to the inner regions it should be supplemented onto the gas phase and we should see a lot of it in the emission with Herschel… that was not the case…

So a lot of the water emission that we see from Herschel is in the outflow, so in the “jet” that we try to map now with JWST fore example. Right. To understand where it's actually coming from… so Herschel is a single dish and you cannot map anything with a single dish instrument except uh for the PACS instrument which gives you different water excitation. So except the Herschel has a number of instruments that can cover the cold water so that's where the water that is being sublimated through energetic photons so that's different water than the inner hot water so there are different water reservoirs in star light information that you tried you have to try to cover them all so there's the jets and outflows and then the inner hot that's where the water gas, water has been sublimated from the ice grains, and also the cold water that is being released onto the gas phase by cosmic rays and energetic photons. So those parts that are not in the outflows are actually lower than expected than before. So what we think is that, the consensus from the water review: it seems that planet formation actually happens very quickly and the way to decrease the amount of water vapor so it doesn't emit is to lock them up in larger dust grains or in very early uh planetesimal (small planetoids like vesta) so this is the origin where the planets are actually forming from.

So the water review discussed that of how the water transported from the molecular cloud, to planet forming regions. It discusses whether or not the water fraction is the same for the earth so trying to understand how old is the water for example so by looking at the spins of water because water has spin states between ortho and para so that's complicated for spectra but the the ortho and para spins is related to the temperature with when it was solidified onto the dust grain and that seems to be consistent with the solar system so it's it also shows that the water on the earth forms very very early before the star is actually important so that's uh one part of the wish program that tries to tackle how early the water is actually formed and then the last part is the complicated story of oxygen right the oxygen is uh it's an element that is crucial for life on earth that we know it um the major carrier of oxygen is of course water in terms of astrochemistry so in terms of chemistry in space but then the crucial component is that we don't know where the oxygen goes so this is called the "unidentified oxygen carriers" so if you sum up all the oxygen carriers it's not exactly the same as what you think the ratios should be but i don't work in this so i don't know the details as much so yes that's one part of the other story that water review has.

Are these two projects related uh in terms of your research interest?

yeah i think the what my research centers is uh is trying to understand how star sun star planet formation goes in terms of their chemical composition and also how to rebuild the physics from those chemical abundances a lot of the oxygen actually is also is known on earth so from the metals and from the oxygen from the soil for example so you can see the oxidation state of the different minerals on earth and you can trace this back to the meteorites and that those meteorites actually tells you what what the physical conditions uh in the past when the planet earth was actually forming and this is one way to connect astronomy and our astrochemistry in general with planetary science and geochemistry. Trying to connect how the earth was born from all these uh different composition that you see in astronomical observations. I don't work directly for the life signatures component but of course water is part of that and only a small part of the chain of our complex life but indeed my collaborators are much more uh much more knowledgeable about this area than i am of course in terms of complex organics that's their main focus. So a lot of complex organics now is seen with ALMA, for example, and you saw them already in the past in the ices. So these complex organics to deform on the dust grains for the most part especially for the oxygen carriers. So yeah it is related.

What is the change that you think your result is going to bring to the non-astronomers? maybe not immediately, but if in 50 years?

um yeah that's a very good questions and i think we will have better understanding of how the earth was actually formed. And also the crucial items how did life actually start on earth. Whether this complex organics and all this complexity chemical compounds are actually set in the early stages of star formations so a lot of the chemistry already happened before the star was actually born, or a lot of processes actually occurred during the planet formation, or it's actually when after the earth was born and then somehow meteorite the asteroids bring it to here, so, we don't know. So i hope that my research can actually contribute the piece to that story by placing the different elements and molecules and see where actually where and when the complexity happens

In our wildest imagination, the world with or without your science, is there going to be a difference? what do you think?

That's difficult to answer um I think the cutting edge that our research is going to bring is to confirm or rather to compare the critical models with observations so not only bringing only observations but also bringing the experimental works to try to confirm whether certain element ratios or some certain isotopes actually consistent with the story that astronomy brings. So this is mostly from the lab experiments such as the one that we're doing in Nan-gang（指位於南港院區的中研院地科所）to see the isotope fractions of different elements to see whether or not there are different reservoirs that are consistent between the astronomy side and planetary science side. We also have models of how the star planet forms for example and hopefully those with the full chemical models to try to explain how early certain elements can be so-cold, can be locked up by this very early planet-forming materials, for example. The only way that certain elements can be excluded from ongoing like from further chemical reactions is to lock them up in larger larger bodies. So this is one of the ways to trace how early planet formation starts and whether or not the formation sequence are consistent with the between the models and the observations.

We focus on the fundamentals and we try to see whether at least a coherent story of how materials actually being transported to earth or any earth-like planets.

You love to do science?

I think science is a way to answer a lot of questions so we have a lot of questions and by doing a lot of scientific uh experiments within astronomy or even in laboratories uh or astronomical observations and lab experiments we can try to answer questions.

That's great.