© 2013 Kalmbach Publishing Co. This material may not be reproduced in any form The next generation without permission from the publisher. www.Astronomy.com Astronomy’s rising stars From studying our solar system to searching for worlds beyond and seeking answers to the universe’s biggest mysteries, these 10 young scientists could change how we see the cosmos. by Karri Ferron

cientists’ understanding of GALACTIC ARCHAEOLOGY RED PLANET WATER “My vision of early Mars how the universe works is Vasily Belokurov A lberto Fairén includes the presence of an changing rapidly. New Cambridge University Cornell University extended ocean on the technology is letting them Vasily Belokurov enters his office every morn- Alberto Fairén is an astrobiologist northern plains, massive ing hoping to understand how the universe — searching for life beyond our polar water ice caps, wide venture into unexplored and particularly the Milky Way — formed. “I planet. And what better place to glaciated terrains rimming territories and collect am a survey scientist and a galactic archaeolo- start than right next door? “During the ocean, and very cold groundbreaking data, while brilliant gist,” Belokurov says. “I trawl through the data my master’s studies, I started learn- liquid water flowing down S of massive sky surveys for clues to the forma- ing about water on early Mars,” he the rivers to that ocean,” minds in the field are using such tion and evolution of our galaxy.” says, “and once you begin working Fairén says. “And all of this information to create a more compre- So far, this digging has led to a better com- on early Mars environments, it was occurring under plan- hensive picture of the cosmos. Many prehension of the Milky Way’s wild past. After becomes difficult to pay attention etary mean freezing tem- analyzing five years of Sloan Digital Sky Survey Dwarf galaxy in Boötes to anything else.” peratures. Water would have of these dedicated astronomers are (SDSS) data, Belokurov and his colleagues cre- Now Fairén combines theoreti- remained in the liquid state just getting started in their careers, ated a dramatic map of stars in the outer por- cal modeling, laboratory experi- at least partially because it and based on their accomplishments tion of our galaxy, dubbed the “Field of Streams.” Such suns represent the remnants ments, field research, and spacecraft data was basically very salty water.” et n

of dwarf galaxies the Milky Way has been gobbling up. “[Our galaxy] pulled them in, / analysis to better understand the Red Planet, Although this is an exciting contribution, II - la

in just the past five to 10 years, their p pulled them apart, and wrapped their material around itself,” Belokurov says. But ASA and he’s already made an important contribu- Fairén isn’t satisfied. Remember, as an astrobi- xo SDSS ); N ); E )/ n . v colleagues and mentors feel strongly there were survivors, which Belokurov’s group also dug up in the SDSS data, includ- i tion to the community with his proposal of ologist, his search is for life. “Life on Earth can airé Un about the influence these young ing one in the constellation Boötes with a total luminosity of only about 10,000 Suns. F a “cold and wet early Mars.” live in environments like those characterizing Calçada ( Calçada . erto erto ridge ridge L b /

Now Belokurov is looking forward to the launch of a new space observatory that l Missions to the Red Planet early Mars, but has it just adapted to those envi- mb A a minds will have on astronomy’s ESO ); ); will add more dimensions to astronomers’ observations. “In about a year’s time, we (C have repeatedly shown evidence ronments, or can it actually originate there?” he v eda ( eda ARS Uc

future. Meet 10 who have recently .

are going to procure a pair of 3-D spectacles,” he says. “The Gaia space mission will R that liquid water was present wonders. “Early Mars sure was habitable, but ) (M )

. supply us with the dimensions currently missing: It will tell us how far the stars are E on or near the surface during was it adequate for originating life?” been recognized for their research A / I ura c ); V. Belokuro V. );

and how quickly they move.” This European Space Agency spacecraft is scheduled v Mars’ early history. Such Ultimately, Fairén’s career goal is ambitious: STS

and discoveries. ( to launch later this year, and Belokurov has big plans for its data: “As I look at the m findings, however, are diffi- “In the end, the reality is that we are looking ea T

stars torn off other celestial bodies as they now travel around the Milky Way, I plan galaxy); dwarf es cult to reconcile with a Sun everywhere we can to try to find something liv- T Ö

Karri Ferron is an Astronomy assistant editor. to study the shape and lumpiness of the gravitational potential that governs their eritage known to be cooler and fainter ing outside Earth. My goal is contributing as H (Bo n le le ) n

orbits. The bulk of the mass generating this potential is in dark matter. In other bb at the same time. But Fairén much as I can to this endeavor, possibly the most u H a-Mora (Vasily Belokuro (Vasily a-Mora oratio n words, my hope is to turn the galaxy into one giant dark matter lab.” b provides an explanation. ambitious and profound human quest.” he he T /

olla Mars ESA illustratio N. Pru N. C

44 Astronomy • July 2013 www.Astronomy.com 45 UNEARTHING EXOPLANETS STAR CYCLES John A. Johnson Jason Kalirai California Institute of Technology Space Telescope Science John A. Johnson didn’t always want to search the skies for worlds Institute around other stars — or even be an astronomer for that matter. He Jason Kalirai knows he’s lucky. started out studying aerospace engineering, then mechanical engi- He gets to work closely with the neering, then physics. After earning his bachelor’s degree, Johnson world’s most famous telescope to decided to study experimental cosmology, but he applied to the study the universe — his astronomy graduate program at the University of California, employer is the headquarters for Berkeley, on a whim — having never taken a single astronomy the Hubble Space Telescope. And course in his life. he’s taking advantage of this “To my surprise, I was admitted to the Berkeley graduate pro- opportunity to measure how gram, and I met with [famous exoplanet hunter] Geoff Marcy during stars evolve so scientists can Red giant star S1020549 my campus visit,” Johnson says. improve their interpretation of Open cluster NGC 2099 “After talking with him and reading the starlight Hubble and other STELLAR an article of his in Astronomy mag- telescopes observe. HISTORY azine, I was hooked on exoplanets.” So far, Kalirai’s work on the initial-final adult, and a grandparent and putting around, the relation is a critical input to Johnson has been studying new mass relation — including studying mem- together a picture of how humans age.” translate unresolved light from any distant Anna Frebel worlds ever since, from gas giants bers of clusters like NGC 2099 — is making Through this research, Kalirai has been galaxy into its fundamental properties — Massachusetts Institute of to diminutive Earth-sized planets. waves. “My research connects the proper- able to show that the Sun will lose 45 per- like the ages of stars in the galaxy.” Technology In the past few years, he and his ties — i.e., mass — of hydrogen-burning cent of its mass as it evolves to become a And Kalirai is just getting started. “I Anna Frebel has been look- colleagues have discovered that stars to the properties of their end products, white dwarf, and that’s just one application. feel my interest in astronomy still hasn’t ing at the stars since she was Jupiter-like planets are much more white dwarfs,” he explains. “By knowing “The initial-final mass relation allows peaked,” he says. “I’ve never thought of my a kid, except now she studies likely to exist around stars more both stellar life-cycle states for the same astronomers to take any pristine stellar ‘job’ as me going to ‘work.’ I want to tackle them through some of the massive than the Sun than around [type of] stars, we can complete a picture of population and evolve it to any age and new mysteries about the universe, and largest instruments in the Sun-like stars or the smallest class how stellar evolution actually happens. This analyze the resulting distribution of star- spending time solving these problems is world. “I consider myself of stars, red dwarfs. “This tells us is much like seeing a baby, a teenager, an light,” Kalirai says. “Turning the argument part of who I am.”

very fortunate that my ini- where to find additional planets /M. ESA tial passion indeed led me to — hint: for gas giants, look around / become a professional stars like Vega and Beta Pictoris; Hot Jupiter prototype astronomer and that my work centers around the oldest stars for rocky planets, look around red in the universe,” she says. “I use these stars to unravel the dwarfs — and provides us with EXOPLANET ATMOSPHERES details of the cosmic evolution of the chemical elements.” valuable clues about the planet- Heather Knutson Frebel has been setting records in her field since 2005. That formation process,” Johnson says. California Institute of Technology

year, she discovered the most chemically primitive star, likely On the lower end of the mass n ) illustratio Ju p iter ( H ot Carreau /C. Despite being the hottest field right now, exoplanet a member of the second generation of stars to have formed in scale, his team has uncovered research occasionally can be boring, as Heather the universe. Then in 2007, Frebel uncovered the oldest three of the smallest planets in N ASA n ); illustratio -961 ( KOI c h L -Calte /JP Knutson will admit. “It’s often a long slog with very known star at the time, a red giant about 13.2 billion years old. data from the Kepler space tele- little progress to show at the end of the day,” she But Frebel wasn’t done. In 2010, she discovered stars like the scope, NASA’s planet-hunting says. But the upside far outweighs the monotony. ); N ASA Joh n so ); . red giant S1020549 in dwarf galaxies with remarkably similar spacecraft, orbiting a star called A “There’s always hope for that ‘aha!’ moment, where

chemical makeups to the Milky Way’s oldest members. “This KOI-961. Now the group is target- (Joh n suddenly everything falls into place and the answer has been helping us gain a better picture of how the Milky Way ing more diminutive suns. “My to your question is staring you in the face.”

assembled and how the oldest stars … actually got incorpo- goal is to build up a large sample of Joh n so . And for Knutson, such moments come when rated into our galaxy, where we can observe them today,” she Earths and sub-Earths so we can A characterizing exoplanetary atmospheres, specifi- says. The effort keeps Frebel busy: “At the moment, I am work- begin to understand the formation cally around a class of short-period gas giant worlds known as hot Jupiters. “Much of ing toward a better understanding of the processes of galaxy of planets like our own throughout our understanding of planetary atmospheres is based on models developed to describe assembly by studying the chemical composition of individual the galaxy,” Johnson says. “These the solar system planets,” she explains. “By studying the properties of planets that stars with a focus on what kind of supernova explosion created discoveries will help us reveal our have the same composition as Jupiter but much hotter atmospheres, we can figure out the observed elements prior to the star’s formation.” planet’s origin story and provide if we really understand planetary atmospheres as well as we thought we did.” All in all, Frebel plans to continue looking into the past as us with a broader galactic context Many colleagues have considered Knutson’s exoplanet observations ground-

part of her future. “My long-term goal is to understand the for our solar system.” ESA n ); Kn utso ( H eather c h H ayashida/Calte L a nc e 2099); (N G C mb ia) Colu British of . breaking. In 2007, her team released the first-ever map of an alien world based on n Joh Courtesy n ); illustratio n t gia ( R ed A ) physical and chemical conditions that governed the early f observations with NASA’s Spitzer Space Telescope that showed the temperature universe soon after the Big Bang, at a time when the first variations across the planet’s entire surface. guilar (C guilar stars and first galaxies began to form,” she says. “My col- A . Such hot Jupiter studies aren’t over for Knutson yet, though. “More recently, I’ve her, et al. ( Un i v et al. R i c her, . id A v id H a leagues and I are working on this by closely combining the / been developing a new project to study how planets form and migrate by searching many observational results with the latest theoretical simula- for additional companions — either stars or planets — in systems that are already tions of galaxy evolution.” known to host a hot Jupiter.” And she expects some surprises: “Many of the biggest alirai); C FHT alirai); K discoveries of the last 10 to 20 years have taken astronomers by surprise; for instance, no one expected to find Jupiter-like planets in three-day orbits around

Astronomy frequently speaks to scientists about (Jaso n I ) LEARN MORE their research. To learn more about their work, c their host stars. Today we say that these planets had to have formed much farther visit www.Astronomy.com/extracontent. out and then migrated inward, but this was a theory developed after the fact.” alirai (for STS (for alirai K 46 Astronomy • July 2013 The KOI-961 planetary system D F re b el); ( Ann a F re b el Ann a Courtesy SUPERNOVA STUDIES Alicia M. Soderberg Harvard-Smithsonian Center for Astrophysics Those who believe scientific discovery is only about luck should talk to Alicia M. Soderberg. “Discovery is usually associated with serendipity,” she admits, “but luck favors the prepared. In this field, you have to be prepared if you want to make impor- tant discoveries.” Such a mantra has proven valuable for Soderberg, who in 2008 became one of the first astronomers to see a star in the act of exploding — a major milestone for the study of supernovae. “I was in the process of observing a supernova in a nearby galaxy [NGC 2770] with the Very Large Array in New Mexico and also the Swift satellite when a second supernova exploded in the same galaxy,” she recalls. Such dual explosions in the same area are Massive-star rare — a 1 in 10,000 occurrence. formation simulation But it wasn’t just luck that allowed Soderberg and her colleagues to study the unex- pected event. Again stressing the connection between luck and preparation, Soderberg recalls that the team “organized a large group to follow the supernova with various tele- STAR BIG BANG BEGINNINGS scopes.” The group recorded the X-rays from the supernova, emission that scientists had SIMULATIONS Hiranya Peiris only theorized to occur before. Through this work, she showed that X-ray satellites could University College London play an important role in earlier detection and observation of such stellar explosions. Mark Krumholz The universe is a very strange place, and studying how it works is a Today, Soderberg leads Harvard University’s Supernova Forensics research group. Her University of California, challenge for cosmologists. Just ask Hiranya Peiris. “My research goals revolve around a holistic study of cosmic explosions that will advance scientists’ Santa Cruz involves confronting confounding problems on a daily basis,” she understanding of the nature and physics of supernovae. “I plan to capitalize on the order Mark Krumholz is a self- “Instead, as a young star says. “On the biggest level, cosmologists are asking the most funda- of magnitude improvement in sensitivity of the Jansky Very Large Array and the Ata- described computer nerd, begins to gather mass, it mental question: Where did everything in the universe come from? cama Millimeter/submillimeter Array,” she notes. “This will enable new discoveries and this interest was key in heats the gas around it, This is something that humans have asked in different forms since S oder b erg); M. A li c ia ( O ffi c e Media regarding supernova properties at longer wavelengths than traditional studies that focus NGC 2770 his decision to go into com- raising its temperature and the dawn of civilization.” primarily on optical data.” putational astrophysics. “It preventing it from frag- Peiris chose to focus on such a tough question after an opportu- had always fascinated me menting any further.” nity during graduate school came up that she couldn’t pass on: that you could build mod- But how much gas participating in a space mission that has now become a corner- els for the world on a com- becomes a star? Scientists stone of modern cosmology, the Wilkinson Microwave Anistropy n Pri nc eto Courtesy (CMB); PLANETARY LAB m puter, and that by plugging know our galaxy contains Probe (WMAP). WMAP spent nine years gathering data related to T ea Sarah T. Stewart in the laws of physics and about 1 billion solar masses the leftover radiation of the Big Bang that still permeates the uni- Harvard University

turning the crank, you worth of star-forming gas verse, known as the cosmic microwave background (CMB). “About Sc ie nc e A P Sometimes finding a career path is as easy W M could figure out what clouds. “If these clouds 1 percent of the snow picked up by an untuned television arises / as combining a hobby with a favorite school would happen in reality.” were simply to collapse from this radiation, generated when the universe was just 0.01 per- subject — at least it was for Sarah T. Stew- Krumholz chose to under their own gravity cent of its present age,” Peiris notes. art. “I grew up a big fan of science fiction focus his computations on and convert their mass into WMAP data have allowed cosmologists to study the CMB like N ASA Peiris); ya — the idea of other planets and civiliza- star formation and the stars, then the Milky Way never before. “I spend my time trying to figure out the physics of tions seemed completely natural — and interstellar medium, and should produce new stars the Big Bang and understand the origin of all the structure we see physics was my favorite science class,” she his research has paid off. at a rate of about 100 solar in the universe,” Peiris says. “I look for fingerprints of these says. “The combination led to my interest For example, a decades- masses worth of new stars extreme physics in the CMB and in large-scale distribution of gal- in planetary physics.”

n ) illustratio t Stewart is known for her laboratory old question surrounds per year,” Krumholz notes. axies in the universe.” c

a Moon-forming giant impact why stars are as massive as But scientists know the rate As missions like WMAP and the current CMB satellite Planck experiments. She and her team particularly they are. “The key part of is actually closer to 1 per- don’t cover the same epochs in the history of the universe as galaxy H ira ( n n der A lexa Max n ); si m ulatio focus on the final stages of planet forma- the answer … is to consider cent of that value. Krum- surveys, Peiris’ research involves creating innovative methods to n atio tion and the role of giant impacts in deter- Recently, Stewart and her colleagues material off Earth to make the Moon out how a protostar that is still holz was able to explain bring all these data together and combine them with theory. By con- ( Imp c h L -Calte /JP mining the resultant physical properties of have made headlines for a model of the of the same material.” forming feeds back on its this phenomenon quantita- tinuing to do so with Planck data and that from the coming decade’s these worlds. “In the lab, we reproduce the Moon’s formation that incorporates the Next up, Stewart’s team is turning its surroundings,” Krumholz tively for the first time. “A large galaxy surveys, Peiris hopes to “probe the way nature works at pressure and temperature conditions similar chemistries of both Earth and its experiments toward a better understanding tar for m ( S tar 2012 K ee c tewart); N ASA S tewart); . says. “Stars form out of likely answer is that the gas extremely high energy scales, a trillion times higher than what we T reached during giant impacts in order to satellite. “The standard giant-impact of all the inner bodies of the solar system. interstellar clouds that are in these clouds is moving can test in the laboratory with particle accelerators. We might even M & , understand when different planetary mate- model predicts that the Moon should be “We are working on how the Moon lost very cold. As long as they around in a violent, super- see hints of how gravity becomes unified with quantum mechanics, rials melt and vaporize,” Stewart explains. made mostly from the impactor, but Earth elements that vaporize easily and yet how stay cold as they collapse, sonic, turbulent fashion,” which is the dream of fundamental physics.” “Then with the computer, we simulate col- and the Moon have identical isotopes,” she Mercury, which formed by a different type they tend to fragment into he says. “One can use the lisions between planetary embryos to explains. “However, if the early Earth were of giant impact, has retained those same

Cosmic microwave background S arah ( O ffi c e News ard smaller and smaller pieces.” statistical properties of tur- v determine how much of the planet melts spinning with a two- to three-hour day elements,” she says. “And we are trying to He and his colleagues dis- bulence to ask what frac- radiation H ar and whether or not certain material can be — much faster than previously thought explain why Venus, Earth, and Mars have covered that the gas sur- tion of the mass is able to lost due to vaporization.” — a giant impact could have launched such different atmospheres.”

rounding the protostar collapse despite the turbu- K lei n K ru m holz, K ru m holz); (Mark U C S doesn’t stay cold forever, lence, and the answer is TO learn more about these 10 young astronomers, visit www.Astronomy.com/toc. cK e n zie/ which stops this process. about 1 percent.” Sn i bb e/ K ris 2770); (N G C ESO J. Ma J. www.Astronomy.com 49