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Dr. Edward Guinan 0:00 [Slide 7] This gives you a distribution, stellar distribution, of stars with spectral type within 10 parsecs, about 33 light years. And we see that M dwarfs dominate with 73% of all stars. K stars are at 44, not 44%, but 13%. And G stars, main sequence G stars are only 4%. So, G stars are rather rare, when it comes to stars in general.

Dr. Edward Guinan 0:33 [Slide 8] Next, please. This plays a role. This is a plot of evolution. It's a luminosity of the star in log scale versus stellar age in billions of years. And we see like an F star, a star like 1.4 solar masses, doesn't live very long. A couple billion years. The sun has a longer time to live, up to about 10 billion years. And its luminosity changes, it gets brighter as the nuclear reaction rates increase, about six and a half to 7% per billion years. What I want you to look at is that the Sun changes. We're now in the inner edge of what's called the habitable zone of the Sun. In a half a billion to 2 billion years, we're no longer in the habitable zone. The habitable zone is where you can have liquid water; we lose that. So, at the bottom there is K stars [which] evolve at 2% increase in luminosity per billion years. And M stars don't change at all. They live a trillion years; that's pointed out here. What should be pointed out is that by the time the Sun ends its life, and becomes a red giant in 10 billion years. A K star has only changed 20% in its luminosity. So, this is like leaning toward what our premise is, is that K stars make better long-term hosts for life.

Dr. Edward Guinan 2:06 [Slide 9] Next slide. These are our scientific slides. We'll just slew through these pretty fast. This is by our student, Casey Purcell, you see her poster here. It shows that the period of rotation of stars, K stars in this case, decrease or increase with age; they spin down. So, when they're young, which is shown at near the 0 to 1 billion years, they're spinning two days, three days per - rotation period of two or three days. At the Sun's age, they're up to 37. And as time goes on, they get into like 50 days. That has an impact. We use this diagram that any star you find in the sky, like a star that's discovered with a planet, and is isolated. You can put it into this diagram, you put the rotation in this diagram, and You can get the approximate age of the star. So, this is called gyro-chronology. And this diagram is used for that. We show the Sun in there, the Sun is sticking right in that area, we're 40 Eridani is. It's 25 days. So, this is the anglular momentum loss over time.

Dr. Edward Guinan 3:19 [Slide 10] Next slide. This gets more complex, but what I want to take quick takeaway here is that when the stars spin fast, they have strong dynamos, magnetic dynamos. So, they have large X-ray emissions and ultraviolet missions shown in the right slide. And as time goes on, these emissions slowly die out. What's to be taken here is that the Sun, for example, if you take the Sun, it was when it was young, its X-ray emissions were 500 times stronger than today. Its ultraviolet emissions were approximately five times stronger than today. This is for K stars, but solar stars have similar things. NASA’s Universe of Learning - 2020-01-08 – Live at AAS - Page 2 of 20

Dr. Edward Guinan 4:03 [Slide 11] Next slide. This is the winds of the star. Winds because they're driven by magnetic phenomena. So, you have young stars that are spinning fast, they have strong winds. In the case of K stars, it's of the order of the 30 times higher than the present day.

Dr. Edward Guinan 4:21 [Slide 12] Next please. This shows you why we're doing this. It turns out that ultraviolet and X- ray radiation and winds that the planet receives has a major effect on the atmosphere of the hosted planet. Far ultraviolet radiation breaks up, dissociates, molecules. I gave an example of water being broken up into hydrogen and oxygen. The X-ray photoionize; they kick out the electrons of these atoms, making ions. And the solar wind, if this planet is not protected by a strong magnetic field, which this planet we show here isn't, the solar winds come in and they pick up the plasmas and drag them off into space. In other words, the atmosphere's evaporated. So, the thing that happens here is that the planet needs a robust geomagnetic field, magnetic field, to prevent the loss of its water inventories and atmosphere. In our own solar system. The only planet, terrestrial planet, with a significant magnetosphere, magnetic field, is the Earth. Mars doesn't have one now, it had one earlier, but it's gone. Venus had one earlier, gone. Mercury had one earlier, gone. The only planet of those planets with life is Earth because it was protected from the Sun's X-ray, UV radiation winds. So that's why we're here. So, we've survived. And I think we're going to turn this over to Scott who can Know the last part of this. So here we go. Next slide. I guess.

Dr. Scott Engle 6:03 [Slide 13] Thank you very much. On this slide, now, as Ed had previously mentioned, we started off studying G type, or solar stars, because obviously, we are orbiting the Sun, so it's proven itself to host habitable planets. But what does all this mean? So, starting off studying G type stars, and moved on to M dwarfs because there are so numerous. As we eventually realized, M stars are so much less luminous than the Sun, the planet has to be close to them in order to receive enough light to be warm enough. But they are almost equal X-ray luminosity and ultraviolet luminosity to the Sun. So now we move on to some actual examples. If you're that close to a K star and to an M star, as you are to a solar type G star, well what are the implications for the X-ray radiation, for the ultraviolet radiation, that you're receiving? So, in this plot, you see some concrete examples of different stars. You see the Sun, you see a planet in orbit around Tau Ceti, Alpha Centauri B, 61 Cygni A, and so on so on. So, the example X-ray irradiances that they would receive relative to Earth equivalent distances. So, if you were receiving the same bolometric radiation, bolometric irradiance that you would receive at the Earth around the Sun, now what's the X-ray radiation you're receiving? If you move on from G type into the K's, everything is pretty much fine. You go up to a few times up to 10 times the X- ray radiation. As you go into the early M dwarfs now, you're up to almost 80 times the X-ray radiation. The planet orbiting Proxima Centauri is receiving 350 or so times the X-ray radiation. The planet orbiting within the "habitable zone," around Trappist 1. As you can see in the text NASA’s Universe of Learning - 2020-01-08 – Live at AAS - Page 3 of 20

there, it's receiving around 1630 times the X-ray radiation that the Earth would receive around the Sun. So it's receiving a pretty intense dosage of X-ray radiation.

Dr. Scott Engle 8:01 [Slide 14] Can we move on to the next slide, please. So, to sum things up within this slide here, the M stars become tricky. They are incredibly attractive targets for planet searches because they are so numerous. You can see in the column saying their relative abundance. And as previously mentioned, they are the most numerous stars around within all the universe, making up roughly 73% of all stars that we know of. And in the last column, their longevity, they have extremely long lifetimes. But within the X-ray irradiance, because you have to be so close to them, because of their luminosities, you are receiving a large X-ray irradiance, a large ultraviolet irradiance. The big X factor here is the planet itself, because there are so many of them. And because we're finding so many planets around them. Yes, it's very possible that with all the different planetary properties out there, that there will be planets that will have magnetic fields and atmospheres with the correct properties that they'll be able to shield themselves. So, they are still very attractive targets for planetary searches. It all comes down to the planet, and whether or not it can shield itself. But we realized that when we went straight from studying the G type stars at the bottom of this figure to the M dwarfs at the top, that we had simply skipped over the K dwarfs within the middle. So that is when we decided to expand our study into these potential Goldilocks targets in the middle there, that perhaps you are a little too close to the M dwarfs receiving a lot of these X-ray and FUV irradiances, now you can move on to the K dwarfs. They are still 13% of all stars, still very attractive targets, and you get to be a little bit closer to them.

Dr. Scott Engle 9:37 [Slide 15] Move on to the next slide, please. And again, some more familiar examples of some of the targets that have been pointed out, that they have planets within their habitable zones. And pointing out some of these and see the FX and the F Lyman alpha. The Lyman alpha emission line is a very good proxy for the ultraviolet irradiance that they receive, and you can see just some of the overall ratios they receive here. Kepler-442b, X-ray irradiances is receiving 50 times, Lyman alpha 4.7 times what the earth is receiving. Proxima Centauri b is at 650 times the X-ray radiance line alpha 17.6 times. And then for the Trappist 1 system is 1630 times the X-ray. Lyman alpha, there is no secure, specific measurement of it. Interpolating from the data that we have, somewhere around 50 times the ultraviolet emissions. Again, it comes down to the planetary properties themselves, which we don't have the data yet to measure. If they have an appropriate atmosphere and magnetic field to shield themselves from that radiation.

Dr. Scott Engle 10:39 [Slide 16] Next slide, please. So, these ones, you might have to shield yourself from [radiation].

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Dr. Scott Engle 10:46 [Slide 17] In the conclusions, well, we know that G stars do work. The only thing they have going against them is that they are actually relatively rare. We're lucky that we are orbiting one we know that you can have habitable planets around them, but they are actually rare, only 5 to 6 percent of all stars out there. The K dwarfs and the M dwarfs especially are much more numerous out there, and have longer lifetimes. But you have to be closer to the star, so you're going to receive more X-ray and FUV radiation.

Dr. Scott Engle 10:47 [Slide 18] Next slide. The bottom line is that, once again, it comes down to the planet itself and whether or not it's going to be able to shield itself from the XUV, the X-ray and the ultraviolet radiation that the planet is going to have to subject itself to, if it is going to be in an orbit that makes itself warm enough for liquid water to exist on the surface.

Dr. Scott Engle 11:33 [Slide 19] Next slide. Thank you very much. Here's our little illustration of the Goldilocks choice there.

Dr. Christopher Britt 11:39 Thank you very much. Now if we have any questions from our audience, we can have time for a quick Q&A before our speakers here have to run to their press conference about their results. So, open the floor to questions from the audience if any come in on WebEx, if Jeff or Quyen could read them out.

Jeffrey Nee 11:58 I just have a big pressing one in terms of Trappist, does that mean it's dampening the excitement about Trappist 1 as being one of the most likely places to find a habitable planet?

Dr. Edward Guinan 12:10 The answer to that is yes. It's receiving, at least, those planets are receiving at least 2000 times more X-rays, then Earth is, and when it was younger, it was more of the order of 1000 times that. So, it seems to us that it's going to be difficult for those planets to have retained atmospheres and water. Yep. Okay.

Jeffrey Nee 12:37 Thanks. That's disappointing, but, but good to know. NASA’s Universe of Learning - 2020-01-08 – Live at AAS - Page 5 of 20

Dr. Christopher Britt 12:42 Excellent question. Are there any others?

Dr. Christopher Britt 12:49 Yes, I had a question just to double check: having a magnetic field, it prevents the stellar wind from picking up the ions that have been produced by the dissociation process, is that correct?

Dr. Scott Engle 13:12 You can shield the atmosphere from the X-ray and the ultraviolet radiation and it will also protect, yes, from the ion pickup process itself. They get deflected into the poles, causing an auroral processes, but yes, it can protect the atmosphere from the radiation.

Unknown Speaker 13:29 But okay I don't see how a magnetic field actually shields that blocks the X-rays.

Dr. Edward Guinan 13:36 The X-ray and UV get in an ionize, and if the solar wind gets in, it drives these ions out.

Dr. Christopher Britt 13:45 Right so it's a two-step process.

Dr. Edward Guinan 13:48 Right the magnetic field doesn't do anything with incoming ultraviolet and X-ray [waves themselves].

Unknown Speaker 13:54 It isn't. Thank you. Yeah, yeah.

Adrienne Provenzano 13:56 This is Adrienne Provenzano, Solar System Ambassador, and my question has to do with that your kind of going with the basic paradigm of "go where the water is." Are there any other liquids NASA’s Universe of Learning - 2020-01-08 – Live at AAS - Page 6 of 20

that are considered to be on the surface? Does your research consider any other possibilities? Like methane or something else?

Dr. Edward Guinan 14:17 If you have a colder planet, you could have something like what's going on at Titan. If you're further out, you know beyond the habitable zone, you can have ammonia, liquid ammonia, liquid methane, and things like that. And who knows? You could have life in those hydrocarbon lakes. Yeah. If you're far out away from the star, there's a lot of things that can help you. This is a circumstellar habitable zone just like we have on our own Solar System: Europa, planets like that, where the solar radiation doesn't factor in. So, the answer is yes. There could be life there. Ammonia is a soluble liquid. So, who knows?

Adrienne Provenzano 15:05 Okay, great. Thank you.

Dr. Christopher Britt 15:06 Hold questions for the moment. So, we're going to move on now to slide number 20. We're going to hear from Dr. Amy Reines, at the University of Montana, about wandering black holes in dwarf galaxies.

Dr. Amy Reines 15:20 Thanks, sorry, I have to correct you. It's Montana State University.

Dr. Christopher Britt 15:25 Sorry, I apologize.

Dr. Amy Reines 15:26 [Slide 20] No problem. So yeah, my name is Amy Reines. I am a professor at Montana State University in beautiful Bozeman, Montana. Today I'm going to tell you about a new and very unexpected discovery of wandering massive black holes in little dwarf galaxies.

Dr. Amy Reines 15:46 [Slide 21] Next slide, please. So yeah, this is an artist's illustration depicting the kind of objects that we found. So, on the left here, we have a dwarf galaxy. So, this is a small galaxy roughly 100 times less massive than our own Milky Way galaxy. And you can see that it has an irregular NASA’s Universe of Learning - 2020-01-08 – Live at AAS - Page 7 of 20

morphology. It looks very different from the giant spiral and elliptical galaxies that you may be more familiar with.

Dr. Amy Reines 16:20 [Slide 22] Next slide. And so, this dwarf galaxy also has a massive black hole roughly 100,000 times the mass of our Sun. The black hole is accreting, or feeding, on surrounding gas. And this produces observable lights, really across the electromagnetic spectrum, including a jet that is detectable at radio wavelengths. Now, this black hole is wandering around the outskirts of the galaxy, far, far away from the center of this galaxy. And this was a surprise. This was not at all what we expected to find.

Dr. Amy Reines 17:03 [Slide 23] Next slide. And that's because these massive black holes are normally found in the centers of galaxies. This is a very famous image now. It's the first image of a black hole that was recently made using the Event Horizon Telescope. And this black hole has a mass of about six and a half billion solar masses, so six and a half billion Suns packed into this small area here. And in fact, we now know that essentially every giant galaxy, including our own Milky Way and M87, this giant elliptical galaxy shown here, these all host central massive black holes, typically with masses of millions, up to billions of solar masses.

Dr. Amy Reines 17:50 [Slide 24] Next. However, the origin of these massive black holes still remains a major outstanding issue in modern astrophysics. We really don't know how these enormous black holes got started in the first place, back in the very early history of our universe.

Dr. Amy Reines 18:07 [Slide 25] Next. We have a fairly good understanding now of how these black holes and their host galaxies grow over time through accreting gas and merging with one another. But we really don't know how these black holes got their start. In other words, we don't know how massive the black hole seeds were when they first formed that ultimately can grow to millions or billions of solar masses.

Dr. Amy Reines 18:34 [Slide 26] Next slide. So, to address this question I've been spending the past several years searching for and studying massive black holes in nearby dwarf galaxies. So, these dwarf galaxies are, again, much smaller than the Milky Way and they host the smallest known black holes. So just from an observational standpoint, they place the most concrete limits on the masses of these first, black hole seeds. NASA’s Universe of Learning - 2020-01-08 – Live at AAS - Page 8 of 20

Dr. Amy Reines 19:03 [Slide 27] Next. While we've made a lot of progress in recent years, particularly using optical spectroscopy, using large surveys, these searches have a number of limitations. For example, they're only sensitive to the most actively feeding black holes that are accreting a lot of material so they can shine brightly at optical wavelengths. And generally, they have to be located in the nuclei of dwarf galaxies. And the galaxies also have to have relatively low amounts of star formation to not mask or mimic the signatures of this black hole accretion. So, these optically selected Black holes are likely just the tip of the iceberg and we're probably missing a bunch.

Dr. Amy Reines 19:50 [Slide 28] Next. Radio observations offer us another avenue to search for these massive black holes in dwarf galaxies and really brought in the parameter space of the detectable population. So, we expect to be able to find a lot more. In other words, there's a lot of potential for new discoveries. And this is highlighted by my discovery number of years ago of a massive black hole in the dwarf Starburst galaxy Henize 2-10. This was actually a serendipitous discovery that I made towards the end of graduate school. I was researching something completely different, and this discovery was aided by the use of high-resolution radio observations and marked an entirely new environment in which to find a massive black hole. So that discovery sort of made me switch my research focus, and really provided a lot of the motivation to conduct the radio survey. That's the focus of my presentation today.

Dr. Amy Reines 20:53 [Slide 29] Next slide, please. So recently I've completed this radio survey of dwarf galaxies in search of massive black holes. This is the first survey of its kind. It was just published on Friday in the Astrophysical Journal.

Dr. Amy Reines 21:09 [Slide 30] Okay, next. So, I obtained observations of 111 dwarf galaxies with the Very Large Array radio telescope in New Mexico shown here. And I chose to observe these particular dwarf galaxies because they were previously detected in the Faint Images of the Radio Sky at Twenty centimeters, or FIRST, radio survey that was previously conducted between about 1993 and 2011. So, I knew they had radio emissions. However, due to the relatively low angular resolution of the FIRST survey, the origin of the radio emissions was unclear. It could be from massive black holes, but it could also just be from intense star formation in these dwarf galaxies. My new VLA observations have a much higher angular resolution than the FIRST survey and they're also much more sensitive so we can detect fainter objects. And these observations ultimately can help us distinguish between massive black holes and star formation as the origin of the radio emissions in these dwarf galaxies.

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Dr. Amy Reines 22:21 [Slide 31] Next, and we found 13 dwarf galaxies containing massive black holes. The optical images of the galaxies Shown here are from the dark energy camera legacy survey, and the red crosses indicate the positions of the radio emission that's coming from these accreting or feeding massive black holes.

Dr. Amy Reines 22:42 [Slide 32] Next, and you can see that the black holes are not always at the centers of their host galaxies. Those red crosses are not always at the center. And I was very surprised when I first saw this because all of the black holes that we've been finding in dwarf galaxies previously had been located in galaxy nuclei as best we could tell. Some of the dwarf galaxies here don't even possess any obvious center, they have irregular morphologies. And some of them show signs of interactions or mergers with other galaxies. And so, while this was quite surprising from an observational standpoint...

Dr. Amy Reines 23:26 [Slide 33] Next, recent simulations, computer simulations, actually predicts that roughly half of all massive black holes in dwarf galaxies are actually expected to be off center, wandering around in the outskirts of their home galaxy.

Dr. Amy Reines 23:44 [Slide 34] Okay, next. And again, this artist's illustration, I think, nicely portrays what we think is going on here. So, these off-center black holes probably result from interactions or mergers between two smaller dwarf galaxies, where at least one of the progenitor dwarf galaxies had a massive black hole that got flung out during the merger. Alternatively, an off-nuclear black hole could result from being ejected by gravitational radiation recoil during the coalescence of two black holes brought in by a dwarf-dwarf merger. So, in any case, whether it's one or the other of these scenarios, once one of these black holes leaves a dwarf galaxy nucleus, it may never return. And this is why we think these off-center black holes may actually be fairly common in dwarf galaxies. And this is in contrast to giant galaxies, full grown galaxies, that have much more massive black holes, which can more easily sink back down to the galaxy nucleus.

Dr. Amy Reines 24:51 [Slide 35] Okay, I believe next slide is the last slide. So, I'll just quickly recap. So, we use the VLA, the Very Large Array, to search for radio signatures of massive black holes in little dwarf galaxies. We discovered 13 dwarf galaxies hosting massive black holes. The masses of these black holes probably averaged around a few hundred thousand solar masses, so they're among the smallest black holes in the smallest galaxies known. We were very surprised to find that these black holes were not always in the centers of these galaxies. But this result is consistent NASA’s Universe of Learning - 2020-01-08 – Live at AAS - Page 10 of 20

with computer simulations predicting that roughly half of massive black holes in dwarfs should be in the outskirts of their hosts. And finally, this work really indicates that we need to broaden our searches beyond dwarf galaxy nuclei for these black holes in order to actually constrain the formation of the black holes. Thank you.

Dr. Christopher Britt 25:57 Thank you very much. Our next speaker is Joey Rodriguez. He's at the Center for Astrophysics at the Harvard Smithsonian. And he's going to be talking to us about how Spitzer confirms the first habitable zone, Earth sized planet from the TES [Transiting Exoplanet Survey] Satellite.

Joey Rodriguez 26:13 [Slide 36] So thank you. I'm going to talk to you today about a really exciting discovery. We heard a bit in the first talk about habitable zone, Earth sized planets like Trappist 1, the Trappist 1 system, the Proxima Centauri system. And in this I'm going to announce the newest habitable zone, Earth sized planet, and actually the first one from the TESS mission and talk about how we use Spitzer to actually confirm it. Just to give you a quick overview of TESS, TESS is an all sky survey looking for planets that are transiting their host star.

Joey Rodriguez 26:48 [Slide 37] And so if I can go to the next slide, just to quickly mentioned, this is a huge collaboration. There are over 100 authors on the first paper. There were three papers in this series announcing the discovery of the first planet. The first paper validates the entire system. It is a three-planet system, which I'll get into. The second paper used Spitzer to confirm the habitable zone, Earth sized planet. And the third paper simulated possible atmospheres for this planet, and what prospects we would have to actually observe them in next generation facilities.

Joey Rodriguez 27:20 [Slide 38] Next slide. So, this is a transit animation. And so, this is one of the movies that is provided.

Dr. Christopher Britt 27:28 So, these are hosted on the website as we've been able to download them from Museum Alliance or from universe-of-learning.org.

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Joey Rodriguez 27:38 And so, both Spitzer and TESS, what they do is they observe transits of planets, which is very simply, as you observe over time, the planet will pass in front of its star periodically blocking out a small part of the light. And the amount of light that the planet blocks out is proportional to the size of the planet relative to the size of the star. So, these types of observations tell us how big the object is.

Joey Rodriguez 28:02 [Slide 39] Next slide. So just a little context on the host star TOI-700 is a red dwarf. It's about 0.41 solar masses. It's about 0.4 solar radii. And we're pretty sure that the star is quite old. It's definitely over about one and a half gigayears. And the star is actually quite close at 101 light years, about 31 parsecs.

Joey Rodriguez 28:29 [Slide 40] Next one. What you're seeing here on the right is actually a composite of the full first year of tests. So, these are 13 different sectors of observations. Each sector is 24 by 96 degrees. And at the center is actually the continuous viewing zone, which is at the ecliptic pole in the southern hemisphere. And fortunately for us TOI-700 was actually right near the ecliptic pole and actually was observed for 11 months, almost continuously, providing a really rich data set for us to look for planets in this system.

Joey Rodriguez 29:02 [Slide 41] Next slide. What you're seeing here is the full light curve from TESS. So, this is the brightness of the star over the 11 months of data. And a few things to note: in blue, you're just seeing the data binned down to about 30 minutes, and on the red is actually the model of a three-planet system that we discovered in this data. A few notes about this data as well is that we do not see a lot of activity. We do not see flares; we do not see a lot of rotation. And so, the star is actually quite quiet, which is a bit different compared to the other known habitable zone, Earth sized planets around low mass stars, like Trappist 1 and Proximus Cen.

Joey Rodriguez 29:43 [Slide 42] Next slide. So, what you're seeing here is the actual architecture of the TOI-700 system. There are three planets. They're all smaller than Neptune. The inner planet is an Earth sized planet at about [an orbital period of] 10 days. The second point is a sub Neptune or mini version of Neptune at about 16 days, and then an Earth sized planet that's orbiting about 38 days, which resides well within the habitable zone for this star. And that is shown in the dark green, and the light green is the optimistic habitable zone.

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Joey Rodriguez 30:16 [Slide 43] Next slide. What you're seeing here is the transit of the inner planet. This is TOI-700 b. It's an Earth sized planet, roughly one Earth radii at 10 days. And we observed a lot of transits of this object.

Joey Rodriguez 30:30 [Slide 44] And next slide please. And the second planet of the system is TOI-700 c. This orbits with a period of about 16 days. At the top, you're seeing the phase folded TESS light curve. So, these are multiple transits over the entire database stacked on top of each other. And we actually observed a transit of this object from the ground using the Las Cumbres Global Telescope network, LCOGT.

Joey Rodriguez 30:56 [Slide 45] And if you - next slide. At the bottom, you can see the actual follow up from the ground that confirmed TOI-700 c and actually refined our confidence in the parameters, specifically that the radius is really about 2.6 Earth radii, and that the period is really about 16 days. And this is important for future studies on this planet because we really need to know these values pretty precisely.

Joey Rodriguez 31:18 [Slide 46] Next slide. But the big reason we're excited about this system is the habitable zone, Earth sized planet. But given the nature of the discovery, it's the first Earth sized planet from the TESS mission. And we are still trying to understand the systematics in the TESS data set. We really want to be completely confident in this discovery and that it was not any kind of false positive or systematic in the data. So, we proposed to get director discretionary time on the Spitzer Space Telescope, and we were awarded two transits of TOI-700 d This was led by my colleague, Dr. Andrew Vanderburg. And the reason that Spitzer is really well suited for this observation is it's much much larger than TESS. And it actually has about 64 times the collecting area. So, it allows us to make this very, very small measurement.

Joey Rodriguez 32:07 [Slide 47] Next Slide. And so, at the top here, you're seeing the TESS light curve for TOI-700 d. This, again, is about eleven transit phases folded on top of each other.

Joey Rodriguez 32:20 [Slide 48] And next one. And at the bottom, you can see the transit that we observed in October from Spitzer, which confirmed that the planet was real, it was not a systematic of the data. And it also, again, allowed us to really refine our understanding of the planet. NASA’s Universe of Learning - 2020-01-08 – Live at AAS - Page 13 of 20

Joey Rodriguez 32:35 [Slide 49] Next one. But many questions still remain, we now have very good confidence in what the size of the planet is. It's about 1.2 Earth radii. It's at a 37-day period. But the big question remains: is this type of planet consistent? Or is it rocky like the terrestrial planets in our solar system? Or is it more like a mini version of Neptune? And that is the big question that we need to answer, and to do that we need to measure the masses of this planet, and to do that we need to use the radial velocity technique.

Joey Rodriguez 33:07 [Slide 50] Next Slide. And so, this is another animation from NASA on the radial velocity technique. And very simply, as a planet orbits around its star, the star will actually orbit around the center of mass of the system and it will appear to wobble. And we can actually detect that wobble. By looking at the spectra of the star over time and watching the spectral lines shift back and forth being redshift and blue shifted due to this wobble, or this change in velocity, of the host star.

Joey Rodriguez 33:42 [Slide 51] Next. What's really interesting is that TOI-700 d tugs, or pulls, on it start off with a velocity of about 80 centimeters per second. And that is very similar to the fastest ground-based turtle that I found, Bertie, which comes from the Guinness World Record for kids, within about a factor of three. So, this is a very, very small measurement that we are trying to make. But it actually is feasible now, given the state of the art, radial velocity instruments that are just coming online or recently came online.

Joey Rodriguez 34:17 [Slide 52] Next slide. So, what I'm showing here is just the radius on the y axis of all small planets, so all planets that are smaller than about 4 Earth radii, versus the amount of light that the planet receives.

Joey Rodriguez 34:29 [Slide 53] Next slide. And so, what I've done here is, in red, I've removed all the planets that are too hot to have liquid water on their surface. In blue, are all the plants that we think, that we know, are too cold to have liquid water on their surfaces. And in gray, I've removed all the planets that are really not Earth sized and that are 50% or more larger than the Earth. And what remains in this small area in white, our about 10 known, habitable, Earth sized systems and the size of the point tells you how accessible it is to make that mass measurement. And TOI-700 d is the most accessible to actually do a direct mass measurement using radial velocity observations. That's mostly because it's so bright. And that was the primary focus of TESS, was NASA’s Universe of Learning - 2020-01-08 – Live at AAS - Page 14 of 20

to observe the brightest and closest stars to our own Sun, those that would be optimal, or well suited, for detailed characterization like mass measurements as well as studies of their atmospheres.

Joey Rodriguez 35:27 [Slide 54] Next slide. And just to show you this is where the Earth would lie on this graph. It has a radius of about one Earth radii, and it receives the light that we have which is what we're scaling this entire plot to

Joey Rodriguez 35:41 [Slide 55] So next slide. We had a third paper. So, the first paper as I mentioned, validated the system and really characterized the host star. The second paper that I led confirmed the habitable zone, Earth sized planet using Spitzer. And the third paper actually explores possible atmospheres about it, and what we could do about observing signatures of these atmospheres going forward in the next generation facilities. And what you're seeing at the top is the phase curve. So, we think this planet is likely to be tidally locked, and therefore will have a hot spot. And as the planet orbits around its star, you will see different phases like you do with the Moon, and therefore that will actually cause a sinusoidal brightness change over time. And this is what you're seeing on the right. Unfortunately, in all cases, no matter what type of Earth's atmosphere that we come up with, the signals are actually quite small, and unfortunately, would not be detected in the era of the James Webb Space Telescope, given what we expect the noise floor to be, which is about 10 parts per million. And as you can see, on the bottom right, the amplitude of this curve is actually about nine parts per million. And this is one of the most optimal cases that we explored.

Joey Rodriguez 36:58 [Slide 56] Next Slide. So, with that, I just kind of want to wrap up and leave my contact information and tell you that we're really excited to find an Earth sized planet in the habitable zone from the TESS mission. This is the first one that we discovered. We do hope to find more, and how many more we find will be dependent on how long TESS flies. So, thank you.

Dr. Christopher Britt 37:20 Thank you very much. I'll open the floor to questions for both of our speakers, both Amy Reines and Joey Rodriguez. So, if anyone has any questions from either the previous talk or this one, then now's the time.

Ken Brandt 37:33 This is Ken Brandt in North Carolina. NASA’s Universe of Learning - 2020-01-08 – Live at AAS - Page 15 of 20

Dr. Christopher Britt 37:37 Hi, go ahead.

Ken Brandt 37:40 Okay. I wanted to ask a question: I'm asked by my students a lot about black holes; they seem to be very concerned about a black hole sucking the Earth. So, my question is for the black hole astronomer: is there any chances that there are wandering black holes in our galaxy?

Dr. Amy Reines 38:00 Yes, there are but you shouldn't worry about them eating things too much along the way. The sphere of influence, so the region around a black hole that can actually [eat] the stuff that will fall into the black hole is pretty small, and the galaxy is really big. So, we don't need to concern ourselves with that. But there certainly could be black holes wandering around just based on our understanding of how galaxies form over time. They tend to start really small early on in the universe and then grow through mergers and accretion. And so, this process could sort of leave our big Milky Way galaxy littered with these massive black holes that came in from smaller satellite galaxies or other dwarf galaxies. So there certainly could be black holes wandering around our own Milky Way.

Ken Brandt 38:54 Thank you very much.

Jeffrey Nee 39:00 Question about slide 32. Some of the black holes seem like they're actually outside of the galaxy. Is that - isn't that weird? I mean, I guess I just want to ask.

Dr. Amy Reines 39:11 Yes. So, we were surprised to find this. But it's actually consistent with these computer simulations that I mentioned. So, if you have galaxies merging with one another, which they tend to do, and if at least one of those has a black hole, just through dynamical interactions, the black hole can sort of get flung out. And because these black holes aren't - they're massive, but they're not as massive as some of the really big ones - they have a harder time sinking back down to the center so they can sort of hang out there longer. And some of these galaxies don't even have well defined centers to go back to.

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Jeffrey Nee 39:55 And then there's a question in the chat about does a galaxy's age have any correlation to the position of the black holes.

Dr. Amy Reines 40:04 So, a galaxy's age, it depends what you mean by that. Like, if you're talking about the ages of the stars in the galaxy, is that what you mean, or look-back time?

Jeffrey Nee 40:16 I mean, how do we measure a galaxy's age?

Dr. Amy Reines 40:19 Right? So, there isn't really one age because there's stars forming. There's a whole star formation history where you get bursts of star formation. And so, it's hard to sort of pin an age of a galaxy. But we haven't really studied the population of the stars so much in these galaxies yet, we just found these black holes. So now we'll do lots of follow up and try to learn about the galaxies themselves, as well. But these are all relatively nearby, in terms of the big scheme of things. So, they're sort of modern-day galaxies, but you can see they're pretty blue. A lot of them have a lot of information, which is fairly common in these lower mass dwarf galaxies. So, I think they just sort of represent the general population of dwarf galaxies actually.

Jeffrey Nee 41:13 Okay, speaking of nearby ones, we have another question in the chatabout the Small and Large Magellanic Clouds. No black holes in those, I'm assuming, maybe?

Dr. Amy Reines 41:22 We don't know. So, none that have been found. Actually, it's very difficult to search there because they're so big on the sky. And again, the sphere of influence of a black hole is small, relatively small, so it's difficult to find them if they are there. And you also really need to worry about contamination from background sources from background, quasars or other AGNs, active galactic nuclei. So, people have looked a little bit, I've dabbled, but it's really hard to do it there.

Dr. Christopher Britt 42:04 Thank you very much. And if there are any other follow up questions that people have, please feel free to reach out so we can get in touch with the speakers to get you an answer to your questions after the day of the briefing. We did want to give an overview very quickly of, before NASA’s Universe of Learning - 2020-01-08 – Live at AAS - Page 17 of 20

we run totally out of time, of other press results that happened in the AAS, presented by James Manning here at NASA's universe of learning. So, this is starting at Slide 57.

James Manning 42:32 [Slide 57] Yes, if we can go to the next slide.

James Manning 42:36 [Slide 58] These are - I won't go into any great detail but you can read these and investigate further. But they're really interesting findings about very large galaxies. It appears to be large not because of mergers with other galaxies, but just because of space. There is some new research on beginning to find markers for "cosmic dawn," when the universe began to get re- ionized as the first stars formed and ionized neutral hydrogen. Hubble is celebrating its 30th anniversary this year, with lots of things to see in the store.

James Manning 42:45 [Slide 59] Next slide. And there was a new fast radio burst discovered, the nearest one, which appears to be coming from a galaxy not so different from the Milky Way, which is a new sort of thing. The speed was clocked out M87's jet at nearly the speed of light, just a little bit under.

James Manning 43:35 [Slide 60] Next slide, please. One really interesting discovery - and you want to keep in mind that you need to eat your vegetables for this - but there was one scientist Schaefer who talked about a cataclysmic binary, which consists of a white dwarf and a rather large main sequence star. They're spinning toward each other and getting brighter, and they've predicted that the two will have what's called a merge burst, a kind of a not quite supernova or kilonova, but it will get very, very bright. And they predict that it's going to do so in 2083 plus or minus 16 years, and it will get as bright as Sirius in the sky at least. So, Everyone, eat your vegetables.

James Manning 44:19 [Slide 61] Next slide, please. Um, let's see. Another really interesting thing is, there's a report on the discovery of a Pleiades-like star cluster. Not that it looks like the Pleiades but appears to consist of stars like those in the Pleiades, which formed in the galactic halo, which is a very odd place for a relatively young, 160-million-year-old star cluster to be. And it's thought that it was formed out of the gas stream that's falling into the handle of our galaxy from the Magellanic Clouds as they themselves begin to fall into the galaxy.

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James Manning 44:56 [Slide 62] Next slide, please. So those are just a couple, just a few little tidbits of really interesting things that were presented at the meeting. And you can of course, investigate further by going to the first link on this page, which is the AAS press kit, or the second link, which is the archived webcasts of the press briefings from this meeting. I don't think both are quite populated with the links to press releases yet or the archived webcast, but they will be shortly. And already we see that if you check NASA news, mission news sites, CNN, space.com, or Google some of these, these bits with keywords, you can really see the number of news articles out talking about many of the discoveries that were announced here at the meeting. So, there's lots to investigate, and we hope that you will do so and learn about what's new in the universe.

Dr. Christopher Britt 45:55 [Slide 63] Thank you very much, Jim. So, at the remainder of our time I just want to mention very briefly that we have collected a number of educational resources, both on exoplanets, on spectroscopy, and on black holes for you all to use in your own programming. So please have a look at those. I won't go through all of them one by one there are too many for our time. But they are provided there in the PDF that you could download. So please have a have a look at those. And I want to mention as well Spitzer featured prominently in the last talk, and this is the last month of Spitzer's operation. So, bon voyage, Spitzer, and Spitzer's IPAC has a website dedicated to its end of mission life at spitzer.caltech.edu/final-voyage, so please visit that as well to find more resources about the Spitzer Space Telescope. So, with any time that we have left if there are any lingering questions, to ask about either of the press conferences that Jim talked about, our resources, or any other questions you have for the speakers. Now, we can take one or two more.

Unknown Speaker 47:16 Yeah, I had a question about the black hole sphere of influence, just how big is that?

Dr. Amy Reines 47:24 So, it depends on the mass of the black hole and the velocity dispersion of the stars around there in the galaxy. But for these black holes of roughly 100,000 solar masses in dwarf galaxies, a typical sphere of influence, I think it's a couple of parsecs, so a few light years or so which is relatively small, if you're thinking about galaxies flying through the Milky Way, which is 100,000 light years across.

Unknown Speaker 47:57 Okay, thank you.

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Jeffrey Nee 48:03 And then I just had a quick question about slide number 45. The dip in the in the light? Am I getting it right that it's only 0.3% of the overall? Is it that tiny?

Joey Rodriguez 48:18 That's correct. It's a very small dip. So, for TOI-700 c, it's about 0.1% but for TOI-700 d, it's 0.07%.

Jeffrey Nee 48:35 Wow. And then I can't remember. TOI stand for what again?

Joey Rodriguez 48:41 Sorry. So, TOI, like its predecessor, Kepler, which used KOI, is TESS Object of Interest. And so all of our targets are objects of interest with a number unless they have a more prominent catalogues name.

Jeffrey Nee 48:56 Great. Thank you.

Joey Rodriguez 48:57 No problem.

Dr. Christopher Britt 49:00 Okay, special thanks to all our speakers for all your time and preparations in making this happen. Sorry about the technical difficulties we had early on. But looks like we finally got it all ironed out. So, this has been live from AAS 2020. Any other further questions that you have, please direct to NASA's universe of learning, and we'll get in touch with the speakers to get those questions addressed. Thank you very much. Bye.

Unknown Speaker 49:31 Thanks, everybody.

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Unknown Speaker 49:33 Thank you. Thanks.

Unknown Speaker 49:36 Thanks for setting this up. Bye.

Transcribed by https://otter.ai and Jeff Nee

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