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Antranik Sefilian, PhD, will be joining the Department of Astronomy to study the dynamics that sculpt planetary systems.

Welcome! Dr. Antranik Sefilian our 2024 51 Pegasi b Fellow

Congratulations to Dr. Antranik Sefilian, who will be joining Steward Observatory as a 2024 51 Pegasi b Fellow, mentored by Department of Astronomy Associate Professor Kaitlin Kratter. During his time at Steward Observatory, Sefilian will be decoding the gravitational interplay between planets, and the remnants of their formation, to illuminate the dynamics that sculpt planetary systems. “We are really excited to host Dr. Sefilian here in Arizona, as he will bring together multiple research groups,” Kratter says. “His theoretical work on debris-disks links those of us who study disk dynamics with our colleagues at the forefront of observational science with JWST. 

Peculiar Orbits and Distant Particles

In the story of planet formation, debris disks stand as enduring relics. These expansive rings of rubble offer astronomers a window into each tumultuous chapter of planetary systems’ formation. By probing these reservoirs of cosmic clues, Sefilian reveals fresh insights into planetary system formation, evolution, and architecture.

Sefilian’s first debris disk study was inspired by the peculiar orbits and clustering of some objects in the Kuiper Belt, a doughnut-shaped region of icy objects beyond the orbit of Neptune. Contrary to the prevailing scientific view attributing their features to a missing Planet Nine (a hypothetical ninth planet in the outer region of the Solar System), he provided theoretical models showing how the collective gravity of Kuiper Belt objects could account for the observations.

“Scientific progress often hinges on serendipitous events,” Sefilian says. “The emergence of the Planet Nine hypothesis sparked a pivotal redirection of my focus.”

Like the pull of distant particles, Sefilian’s own career has been guided by serendipity. He grew up in Lebanon, where opportunities in astrophysics are scarce. Yet, he found mentorship from the only theoretical astrophysicist working in planetary dynamics in the country.

During his fellowship, Sefilian will continue exploring gravitational interactions between planets and debris disks, collaborating with observers to test his predictions. His models can be adapted to many debris disk scenarios and simulate their evolution with unprecedented speed and adaptability. From unraveling the structures of debris disks, including warps and elliptical features, to simulating colliding debris, Sefilian’s research promises to transform our understanding of planetary systems.

Sefilian received a Ph.D. in applied mathematics and theoretical physics from the University of Cambridge in Spring 2022. Prior to starting his fellowship, Sefilian will continue to work as an Alexander von Humboldt fellow at the University of Jena in Germany.

A Fellowship for Experimental Planetary Research

Established in 2017, the Heising-Simons Foundation 51 Pegasi b Fellowship is named for the first exoplanet discovered orbiting a Sun-like star. In the growing field of planetary astronomy, scientists study objects both within and beyond our solar system, bridging planetary science and astronomy. From improving our understanding of planetary system formation and evolution, to advancing new technologies for detecting other worlds, 51 Pegasi b Fellows make a unique contribution to the field. This year, the fellowship provides eight postdoctoral scientists with the opportunity to conduct theoretical, observational, and experimental research in planetary astronomy.

“The 51 Pegasi b fellowship is a unique opportunity aimed at helping to launch the careers of young scientists working in the field of planets and planet formation,” Kratter says. “The Heising-Simons foundation has created a very supportive system, combining competitive stipends and research budgets with exceptional professional development skills in the form of workshops and on-one-on mentoring relationships. We are very lucky here in Arizona to have the opportunity to host another fellow through this program.”

A Pivotal Time for Science at Steward

Sefilian’s research interests come at a time when the capabilities of cutting-edge telescopes will allow the postdoc to test his theories against real-life observations. It’s an especially connective time to be at Steward Observatory, which is home to the MIRI and NIRCam team leaders who developed the infrared instrumentation for the James Webb Space Telescope (JWST). “With the unprecedented capabilities of instruments such as JWST and ALMA, the boundaries between theory and observations are rapidly dissolving,” Sefilian says. “This convergence promises to test many of my theoretical predictions, and that’s really exciting.”

 

Steward Observatory Professor Teaches Indigenous College Students About the Stars

Before Dr. Virginie Faramaz arrived at Steward Observatory as an assistant research professor, she had earned her PhD in exoplanetary system dynamics"trying to predict planets from the shape of comet belts"and she had completed two postdocs: one in Chile, and another at the Jet Propulsion Lab." She became faculty at University of Arizona during the pandemic, and she is currently interested in how planetary systems within the habitable zone of stars retrieve organic materials and water from beyond what she calls the "ice line." Her work will help researchers choose exoplanets to observe that are likeliest to harbor life."

But alongside her interest in faraway planets and the hunt for clues of life beyond Earth, Faramaz arrived in Tucson with the hope of teaching. This year, that dream came true: she was invited to lead an online course for the San Carlos Apache College (SCAC) in conjunction with the Tohono O'odham Community College (TOCC), following in the footsteps of Steward Observatory's Peter Milne, who taught introductory astronomy in this setting last year. Stepping beyond her research and into the virtual classroom, Faramaz now teaches about the solar system to indigenous students from as far away as Nebraska.

Faramaz believes that her introductory course in astronomy sets students up for skills that reach far beyond astronomy, from critical thinking to physics. "We touch on a little bit of everything," she says. This is what initially drew her to astronomy as a student, too: she double-majored in physics and chemistry, and when she went on to pursue her master"s degree, she discovered that astronomy spanned all her interests. If her TOCC students "come away with some general knowledge of the universe, and some sense of wonder, and some sense of how science works, and if they have a little bit of critical thinking "that's what I hope they will get out of the class."

This semester, Faramaz is learning as much from her students as they are learning from her. For example, Apache students in her class taught her that wintertime is traditionally the only time when stories about the night sky can be told"so in the early months of the semester, before winter turned to spring, Faramaz asked the class to share myths about the cosmos with each other. Some shared stories from as far away as Greece and the Yakama Nation. One student described how the Yomi people describe the universe as being made up of nine layers. Another student taught the class how the Big Dipper is called "the hook," describing the Tohono O'odham tool used during the local saguaro harvest to pluck fruit from the tops of tall cacti.

Between sharing stories about constellations and learning about quantum physics and spectral lines, the wonder of astronomy permeates Faramaz" class. "The immensity of space and the universe is so mind blowing," she says. "I hope it will give them the impulse to push further with their education."

On March 26th, Faramaz talks with the Tohono O'odham Community College radio station about her introductory astronomy class. The show airs locally on 3/26/2024 between 2 pm and 4 pm MST:

 

KWAK LP 102.5 (San Xavier Community)

KOHF LP 101.1 FM (Florence)

KOHN 91.9 FM (Sells)

KOHH 90.7 FM (San Lucy)

Featured in a radio segment airing Tuesday March 26th, Dr. Virginie Faramaz teaches an introductory astronomy class at the Tohono O'odham Community College, bringing University of Arizona curriculum to students from Tribal nations across the country

GUSTO aims to map out distribution of carbon, oxygen and nitrogen in the young Milky Way and in the neighboring Large Magellanic Cloud, which has characteristics comparable to much older galaxies. A comparison of the two galaxies will help the GUSTO team provide the first complete spectroscopic study of all phases of the stellar life cycle, from the development of interstellar gas clouds, to the formation of stellar nurseries, to the birth and evolution of stars.

If Walker's next research proposal goes through, the same instrumentation currently aboard GUSTO may be tested in space, in search of the elusive far infrared signatures of planet-forming systems and habitable zones.

"If you're not pushing the edge, what's the point?" Walker said.

Read more

AZPM: interview with Steward Observatory astronomy professor Chris Walker

Kate is not just among the leaders working to discover and observe transient sources, she is also a driving force for the ambitious efforts to understand the physics behind their spectacular and astonishing observed properties.” – Buell Jannuzi, Director of Steward Observatory

Dr. Alexander took a lead role in understanding the gamma ray burst event GRB 221009A: the brightest cosmic explosion ever seen by humanity. The Sloan Fellowship will help further her study of energetic transients, in particular the high-energy jets associated with black holes as they consume stars.

Webb telescope takes its first images of forming planetary systems

A team led by Jarron Leisenring at the UArizona Steward Observatory has obtained the deepest look yet into planetary nurseries.

By taking advantage of the dust-penetrating capabilities of the James Webb Space Telescope's infrared instruments, designed and built in part by University of Arizona scientists, astronomers have obtained the first direct observations with the new space telescope of gas and dust feeding a nascent planetary system with raw material for planet formation.

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The observations help astronomers refine their theories about the processes involved in planet formation and shed light on what our sun did when it was very young.

A Steward Postdoc Tells Cosmic Stories for Kids

This fall, Dr. Jaclyn Champagne, our JASPER postdoc researcher at Steward Observatory, wrote a compelling piece for The Conversation about the environments where colossal black holes form (Powerful black holes might grow up in bustling galactic neighborhoods).

The story was so popular that Astronomy Magazine re-published it, and The Conversation asked Dr. Champagne if she might be able to write a story for children about her research area. The result: a kid-friendly article that explores why some black holes are bigger than others. Read it here, and be sure to share it with the curious young readers in your life!

On the morning of January 11, 2024, Dennis Zaritsky, Deputy Director and Astronomer at Steward Observatory, received the Beatrice M. Tinsley Prize from the American Astronomical Society, in recognition of an outstanding research contribution to astronomy or astrophysics, of an exceptionally creative or innovative character. 

Zaritsky studies the hidden parts of galaxies—not the easily visible galactic center, but the massive and mysterious halo that surrounds each galaxy, made up of dark matter, diffuse gas and dim stars that are hard to track down. He picks up clues about the nature of galaxy halos by studying the spectra taken of other galaxies. Unique galaxy halo signatures will appear along the line of sight to the target galaxy, like different-colored theater gels stacked in front of a light. Using exposures of galaxies from the Sloan Digital Sky Survey, Zaritsky can unveil the many layers of spectrographic information about neighboring galaxy halos embedded in each observation. A typical exposure from the Sloan Survey spends about 45 minutes per exposure, but by combining them, “we had effective observations that were millions of hours long,” Zaritsky says.

Finding inventive solutions like this is one of Zaritsky’s greatest joys in his research. “People outside of science tend to see the arts as being creative, and science as just calculating things, but it really can be quite creative,” Zaritsky says. “That's the part I enjoy the most.”

Zaritsky’s artistry is helping paint a better picture of the dimly-lit story of galaxy evolution. By pinpointing hard-to-observe elements of galactic halos like dark matter, gas and dust, Zaritsky is honing an understanding of how galaxies accrete mass and create new stars.

Dennis began this research as a graduate student at the UArizona Department of Astronomy, where he wrote his thesis on dark matter in galaxy halos. He was drawn to the amount of freedom that graduate students at Steward Observatory are given to shape their studies. The Department of Astronomy continues to offer an “exciting place to work,” he says.  Zaritsky admires “the breadth of the science that is done, the telescope access, and the very open attitude” toward researchers pursuing their curiosities. The observatory has a strong legacy of scientists who began their UArizona time as graduate students and have since stepped into roles as leaders and faculty, including Buell Jannuzi, Head of the Department of Astronomy and Director of Steward Observatory. Of Zaritsky’s Tinsley Prize, Jannuzi says “I’m thrilled the AAS is recognizing Dennis’s creativity and impactful research. We are fortunate that such a talented researcher is also willing and able to contribute so effectively to our teaching mission as well.” 

In looking ahead to what’s next, Zaritsky describes the challenge of dust: the diffuse, smoke-like material that floats in the space between stars. Zaritsky is currently working with international collaborators to use the Large Binocular Telescope Observatory (LBTO)—with enormous twin mirrors made at the Richard F. Caris Mirror Lab below the UArizona football stadium—to investigate cosmic dust. The team plans to resolve exceptionally deep images of nearby galaxies—deeper even than the Vera C. Ruben Observatory aims to take in its upcoming decade-long Legacy Survey of Space and Time. They will be measuring the quantity, structure, and distribution of dust to look for trends and to visualize how far the dust extends. 

This will have implications for many of the most advanced earth- and space-based telescopes, which focus on the most faraway objects in the universe. Understanding the ways that dust constrains visibility (what Zaritsky calls the “veil of extinction ”) may also lead to better modeling for how to pierce the veil for a clearer view of our distant origins. 

Featured in a radio segment airing Tuesday March 26th, Dr. Virginie Faramaz teaches an introductory astronomy class at the Tohono O'odham Community College, bringing University of Arizona curriculum to students from Tribal nations across the country

Steward Observatory Professor Teaches Indigenous College Students About the Stars

Steward Observatory Professor Teaches Indigenous College Students About the Stars

Before Dr. Virginie Faramaz arrived at Steward Observatory as an assistant research professor, she had earned her PhD in exoplanetary system dynamics"trying to predict planets from the shape of comet belts"and she had completed two postdocs: one in Chile, and another at the Jet Propulsion Lab." She became faculty at University of Arizona during the pandemic, and she is currently interested in how planetary systems within the habitable zone of stars retrieve organic materials and water from beyond what she calls the "ice line." Her work will help researchers choose exoplanets to observe that are likeliest to harbor life."

But alongside her interest in faraway planets and the hunt for clues of life beyond Earth, Faramaz arrived in Tucson with the hope of teaching. This year, that dream came true: she was invited to lead an online course for the San Carlos Apache College (SCAC) in conjunction with the Tohono O'odham Community College (TOCC), following in the footsteps of Steward Observatory's Peter Milne, who taught introductory astronomy in this setting last year. Stepping beyond her research and into the virtual classroom, Faramaz now teaches about the solar system to indigenous students from as far away as Nebraska.

Faramaz believes that her introductory course in astronomy sets students up for skills that reach far beyond astronomy, from critical thinking to physics. "We touch on a little bit of everything," she says. This is what initially drew her to astronomy as a student, too: she double-majored in physics and chemistry, and when she went on to pursue her master"s degree, she discovered that astronomy spanned all her interests. If her TOCC students "come away with some general knowledge of the universe, and some sense of wonder, and some sense of how science works, and if they have a little bit of critical thinking "that's what I hope they will get out of the class."

This semester, Faramaz is learning as much from her students as they are learning from her. For example, Apache students in her class taught her that wintertime is traditionally the only time when stories about the night sky can be told"so in the early months of the semester, before winter turned to spring, Faramaz asked the class to share myths about the cosmos with each other. Some shared stories from as far away as Greece and the Yakama Nation. One student described how the Yomi people describe the universe as being made up of nine layers. Another student taught the class how the Big Dipper is called "the hook," describing the Tohono O'odham tool used during the local saguaro harvest to pluck fruit from the tops of tall cacti.

Between sharing stories about constellations and learning about quantum physics and spectral lines, the wonder of astronomy permeates Faramaz" class. "The immensity of space and the universe is so mind blowing," she says. "I hope it will give them the impulse to push further with their education."

On March 26th, Faramaz talks with the Tohono O'odham Community College radio station about her introductory astronomy class. The show airs locally on 3/26/2024 between 2 pm and 4 pm MST:

 

KWAK LP 102.5 (San Xavier Community)

KOHF LP 101.1 FM (Florence)

KOHN 91.9 FM (Sells)

KOHH 90.7 FM (San Lucy)

Jackie Champagne

A Steward Postdoc Tells Cosmic Stories for Kids

This fall, Dr. Jaclyn Champagne, our JASPER postdoc researcher at Steward Observatory, wrote a compelling piece for The Conversation about the environments where colossal black holes form (Powerful black holes might grow up in bustling galactic neighborhoods). The story was so popular that Astronomy Magazine re-published it, and The Conversation asked Dr. Champagne if she might be able to write a story for children about her research area. The result: a kid-friendly article that explores why some black holes are bigger than others. Read it here, and be sure to share it with the curious young readers in your life!

 

New images taken with the James Webb Space Telescope reveal intricate, never-before-seen structures and features hidden in visible light. The insights will help astronomers better understand the history of the Milky Way.

Click here to read more.

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