Welcome to GeoUnion, the graduate student body of the Department of Earth, Environmental and Planetary Sciences. GeoUnion strives to supplement the overall graduate student experience at Rice and DEEPS. GeoUnion represents DEEPS in the overall Rice grad student community, acts as a liaison between students and faculty and organizes a number of intra- and inter-departmental events throughout the academic year.
Date | Event |
---|---|
August 19-23 | O-Week |
September 6-8 | Overnight Camping at San Marcos |
September 13 | Welcome Barbecue |
Cancelled because of Imelda | Pre-GSA talk |
October 12-15 | Field Trip to Big Bend |
October 25 | Halloween Kickball Tournament |
November 26 | Multicultural Thanksgiving! |
Dec 6 | Pre-AGU practice session |
TBA | Enlightenment |
Here’s a list of the resources that you would need to use frequently as graduate students at Rice. The websites of the Rice Graduate Student Association (GSA), Office of International Students and Scholars (OISS), Graduate and Postdoctoral Studies (GPS) are platforms which graduate students can use to keep track of upcoming events, funding opportunities, changes in rules and regulations, etc.
Living in a vast city like Houston and exploring a new place can also be challenging, and so we have compiled a list of recommendations for housing and fun things to do in the Space City!
Ken Kennedy Institute Graduate Fellowship Program Awards to Morgan Underwood
The Ken Kennedy Institute’s annual graduate fellowship program has awarded $65,000 to nine Rice graduate students in five departments.
Recipients use fellowship awards to further research pursuits, attend conferences, travel, and develop networking relationships in industry. Past recipients have spent summers as research interns with sponsoring companies.
An important aspect of the fellowships is presenting research at Ken Kennedy Institute’s annual Energy High Performance Computing Conference, a gathering of more than 500 leaders and experts in high performance computing, computational science and engineering, machine learning, and data science.
With the support of industry, the conference, and nominating departments (for recruiting fellowships), the Ken Kennedy Institute has awarded nearly $1.5 million to 172 students since 2001. The 2021-22 graduate fellowships are supported by BP, Schlumberger, Shell, the Energy High Performance Computing Conference, and the Andrew Ladd and Ken Kennedy-Cray endowments.
We congratulate the 2021-22 fellowship recipients:
- Shabnam Daghaghi, electrical and computer engineering: BP, $7,500
- Luqin Gan, statistics: Shell, $7,500
- Bishal Lamichhane, electrical and computer engineering: Energy HPC Conference, $7,500
- Thiago Jose Pinheiro dos Santos, chemical and bimolecular engineering: Energy HPC Conference, $7,500
- Xin Tan, statistics: Energy HPC Conference, $7,500
- Morgan Underwood, earth, environmental, and planetary sciences: Ken Kennedy-Cray, $7,500
- Zichao (Jack) Wang, electrical and computer engineering: Schlumberger, $7,500
- ZhaoZhuo Xu, computer science: BP, $7,500
- Zhiwei Zhang, computer science: Andrew Ladd, $5,000
Author: THE KEN KENNEDY INSTITUTE
Earth isn’t ‘super’ because the sun had rings before planets
‘Pressure bumps’ in sun’s protoplanetary disk explain many solar system features
HOUSTON – (Jan. 5, 2021) – Before the solar system had planets, the sun had rings — bands of dust and gas similar to Saturn’s rings — that likely played a role in Earth’s formation, according to a new study.
“In the solar system, something happened to prevent the Earth from growing to become a much larger type of terrestrial planet called a super-Earth,” said Rice University astrophysicist André Izidoro, referring to the massive rocky planets seen around at least 30% of sun-like stars in our galaxy.
Izidoro and colleagues used a supercomputer to simulate the solar system’s formation hundreds of times. Their model, which is described in a study published online in Nature Astronomy, produced rings like those seen around many distant, young stars. It also faithfully reproduced several features of the solar system missed by many previous models, including:
- An asteroid belt between Mars and Jupiter containing objects from both the inner and outer solar system.
- The locations and stable, almost circular orbits of Earth, Mars, Venus and Mercury.
- The masses of the inner planets, including Mars, which many solar system models overestimate.
- The dichotomy between the chemical makeup of objects in the inner and outer solar system.
- A Kuiper belt region of comets, asteroids and small bodies beyond the orbit of Neptune.
The study by astronomers, astrophysicists and planetary scientists from Rice, the University of Bordeaux, Southwest Research Institute in Boulder, Colorado, and the Max Planck Institute for Astronomy in Heidelberg, Germany, draws on the latest astronomical research on infant star systems.
Their model assumes three bands of high pressure arose within the young sun’s disk of gas and dust. Such “pressure bumps” have been observed in ringed stellar disks around distant stars, and the study explains how pressure bumps and rings could account for the solar system’s architecture, said lead author Izidoro, a Rice postdoctoral researchers who received his Ph.D. training at Sao Paulo State University in Brazil.
“If super-Earths are super-common, why don’t we have one in the solar system?” Izidoro said. “We propose that pressure bumps produced disconnected reservoirs of disk material in the inner and outer solar system and regulated how much material was available to grow planets in the inner solar system.”
Pressure bumps
For decades, scientists believed gas and dust in protoplanetary disks gradually became less dense, dropping smoothly as a function of distance from the star. But computer simulations show planets are unlikely to form in smooth-disk scenarios.
“In a smooth disk, all solid particles — dust grains or boulders — should be drawn inward very quickly and lost in the star,” said astronomer and study co-author Andrea Isella, an associate professor of physics and astronomy at Rice. “One needs something to stop them in order to give them time to grow into planets.”
When particles move faster than the gas around them, they “feel a headwind and drift very quickly toward the star,” Izidoro explained. At pressure bumps, gas pressure increases, gas molecules move faster and solid particles stop feeling the headwind. “That’s what allows dust particles to accumulate at pressure bumps,” he said.
Isella said astronomers have observed pressure bumps and protoplanetary disk rings with the Atacama Large Millimeter/submillimeter Array, or ALMA, an enormous 66-dish radio telescope that came online in Chile in 2013.
“ALMA is capable of taking very sharp images of young planetary systems that are still forming, and we have discovered that a lot of the protoplanetary disks in these systems are characterized by rings,” Isella said. “The effect of the pressure bump is that it collects dust particles, and that’s why we see rings. These rings are regions where you have more dust particles than in the gaps between rings.”
Ring formation
The model by Izidoro and colleagues assumed pressure bumps formed in the early solar system at three places where sunward-falling particles would have released large amounts of vaporized gas.
“It’s just a function of distance from the star, because temperature is going up as you get closer to the star,” said geochemist and study co-author Rajdeep Dasgupta, the Maurice Ewing Professor of Earth Systems Science at Rice. “The point where the temperature is high enough for ice to be vaporized, for example, is a sublimation line we call the snow line.”
In the Rice simulations, pressure bumps at the sublimation lines of silicate, water and carbon monoxide produced three distinct rings. At the silicate line, the basic ingredient of sand and glass, silicon dioxide, became vapor. This produced the sun’s nearest ring, where Mercury, Venus, Earth and Mars would later form. The middle ring appeared at the snow line and the farthest ring at the carbon monoxide line.
Rings birth planetesimals and planets
Protoplanetary disks cool with age, so sublimation lines would have migrated toward the sun. The study showed this process could allow dust to accumulate into asteroid-sized objects called planetesimals, which could then come together to form planets. Izidoro said previous studies assumed planetesimals could form if dust were sufficiently concentrated, but no model offered a convincing theoretical explanation of how dust might accumulate.
“Our model shows pressure bumps can concentrate dust, and moving pressure bumps can act as planetesimal factories,” Izidoro said. “We simulate planet formation starting with grains of dust and covering many different stages, from small millimeter-sized grains to planetesimals and then planets.”
Accounting for cosmochemical signatures, Mars’ mass and the asteroid belt
Many previous solar system simulations produced versions of Mars as much as 10 times more massive than Earth. The model correctly predicts Mars having about 10% of Earth’s mass because “Mars was born in a low-mass region of the disk,” Izidoro said.
Dasgupta said the model also provides a compelling explanation for two of the solar system’s cosmochemical mysteries: the marked difference between the chemical compositions of inner- and outer-solar system objects, and the presence of each of those objects in the asteroid belt between Mars and Jupiter.
Izidoro’s simulations showed the middle ring could account for the chemical dichotomy by preventing outer-system material from entering the inner system. The simulations also produced the asteroid belt in its correct location, and showed it was fed objects from both the inner and outer regions.
“The most common type of meteorites we get from the asteroid belt are isotopically similar to Mars,” Dasgupta said. “Andre explains why Mars and these ordinary meteorites should have a similar composition. He’s provided a nuanced answer to this question.”
Pressure-bump timing and super-Earths
Izidoro said the delayed appearance of the sun’s middle ring in some simulations led to the formation of super-Earths, which points to the importance of pressure-bump timing.
“By the time the pressure bump formed in those cases, a lot of mass had already invaded the inner system and was available to make super-Earths,” he said. “So the time when this middle pressure bump formed might be a key aspect of the solar system.”
Izidoro is a postdoctoral research associate in Rice’s Department of Earth, Environment and Planetary Sciences. Additional co-authors include Sean Raymond of the University of Bordeaux, Rogerio Deienno of Southwest Research Institute and Bertram Bitsch of the Max Planck Institute for Astronomy. The research was supported by NASA (80NSSC18K0828, 80NSSC21K0387), the European Research Council (757448-PAMDORA), the Brazilian Federal Agency for Support and Evaluation of Graduate Education (88887.310463/2018-00), the Welch Foundation (C-2035) and the French National Centre for Scientific Research’s National Planetology Program.
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DOI: 10.1038/s41550-021-01557-z
Read the Nature Astronomy paper at: https://doi.org/10.1038/s41550-021-01557-z.
High-resolution IMAGES are available for download at:
https://news-network.rice.edu/news/files/2021/12/1220_RINGS-aiF3-lg.jpg
CAPTION: The addition of false color to an image captured by the Atacama Large Millimeter/submillimeter Array, or ALMA, reveals a series of rings around a young star named HD163296. (Image courtesy of Andrea Isella/Rice University)
https://news-network.rice.edu/news/files/2021/12/1220_RINGS-Nfo-lg.jpg
CAPTION: An illustration of three distinct, planetesimal-forming rings that could have produced the planets and other features of the solar system, according to a computational model from Rice University. The vaporization of solid silicates, water and carbon monoxide at “sublimation lines” (top) caused “pressure bumps” in the sun’s protoplanetary disk, trapping dust in three distinct rings. As the sun cooled, pressure bumps migrated sunward allowing trapped dust to accumulate into asteroid-sized planetesimals. The chemical composition of objects from the inner ring (NC) differs from the composition of middle- and outer-ring objects (CC). Inner-ring planetesimals produced the inner solar system’s planets (bottom), and planetesimals from the middle and outer rings produced the outer solar system planets and Kuiper Belt (not shown). The asteroid belt formed (top middle) from NC objects contributed by the inner ring (red arrows) and CC objects from the middle ring (white arrows). (Image courtesy of Rajdeep Dasgupta)
https://news-network.rice.edu/news/files/2021/12/1220_RINGS-Fit02-lg.jpg
CAPTION: Rajdeep Dasgupta (left) and Andre Izidoro. (Photo by Jeff Fitlow/Rice University)
https://news-network.rice.edu/news/files/2021/12/1220_RINGS-aiV-lg.jpg
CAPTION: Andrea Isella (Photo by Jeff Fitlow/Rice University)
This release can be found online at news.rice.edu.
Air bubbles in Antarctic ice point to cause of oxygen decline
Jade Boyd – Dec. 20, 2021
Glacial erosion likely caused atmospheric oxygen levels to dip over past 800,000 years
HOUSTON – (Dec. 20, 2021) – An unknown culprit has been removing oxygen from our atmosphere for at least 800,000 years, and an analysis of air bubbles preserved in Antarctic ice for up to 1.5 million years has revealed the likely suspect.
“We know atmospheric oxygen levels began declining slightly in the late Pleistocene, and it looks like glaciers might have something to do with that,” said Rice University’s Yuzhen Yan, corresponding author of the geochemistry study published in Science Advances. “Glaciation became more expansive and more intense about the same time, and the simple fact that there is glacial grinding increases weathering.”
Weathering refers to the physical and chemical processes that break down rocks and minerals, and the oxidation of metals is among the most important. The rusting of iron is an example. Reddish iron oxide forms quickly on iron surfaces exposed to atmospheric oxygen, or O2.
“When you expose fresh crystalline surfaces from the sedimentary reservoir to O2, you get weathering that consumes oxygen,” said Yan, a postdoctoral research associate in Rice’s Department of Earth, Environmental and Planetary Sciences.
Another way glaciers could promote the consumption of atmospheric oxygen is by exposing organic carbon that had been buried for millions of years, Yan said.
During Yan’s Ph.D. studies in the labs of Princeton University’s Michael Bender and John Higgins, Yan worked on a 2016 study led by Daniel Stolper, now an assistant professor at the University of California, Berkeley, that used air bubbles in ice cores to show the proportion of oxygen in Earth’s atmosphere had declined by about 0.2% in the past 800,000 years.
In the Science Advances study, Yan, Higgins and colleagues from Oregon State University, the University of Maine and the University of California, San Diego, analyzed bubbles in older ice cores to show the O2 dip began after the length of Earth’s glacial cycles more than doubled around 1 million years ago.
The ice age Earth is in today began about 2.7 million years ago. Dozens of glacial cycles followed. In each, ice caps alternately grew, covering up to a third of the planet, and then retreated toward the poles. Each cycle lasted around 40,000 years until about 1 million years ago. At roughly the same time atmospheric oxygen began to decline, glacial cycles began lasting about 100,000 years.
“The reason for the decline is the rate of O2 being produced is lower than the rate of O2 being consumed,” Yan said. “That’s what we call the source and the sink. The source is what produces O2, and the sink is what consumes or drags on O2. In the study, we interpret the decline to be a stronger drag on O2, meaning more is being consumed.”
Yan said Earth’s biosphere didn’t contribute to the decline because it is balanced, drawing as much O2 from the atmosphere as it produces. Weathering, on a global scale, is the most likely geological process capable of consuming enough excess O2 to account for the decline, and Yan and colleagues considered two scenarios for increased weathering.
Global sea level falls when glaciers are advancing and rises when they retreat. When the length of glacial cycles more than doubled, so did the magnitude of swings in sea level. As coastlines advanced, land previously covered by water would have been exposed to the oxidizing power of atmospheric O2.
“We did some calculations to see how much oxygen that might consume and found it could only account for about a quarter of the observed decrease,” Yan said.
Because the extent of ice coverage isn’t precisely known for each glacial cycle, there’s a wider range of uncertainty about the magnitude of chemical weathering from glacial erosion. But Yan said the evidence suggests it could draw enough oxygen to account for the decline.
“On a global scale, it’s very hard to pinpoint,” he said. “But we did some tests about how much additional weathering would be needed to account for the O2 decline, and it’s not unreasonable. Theoretically, it could account for the magnitude of what’s been observed.”
Additional co-authors include Edward Brook of Oregon State, Andrei Kurbatov of the University of Maine and Jeffrey Severinghaus of UC San Diego. The research was supported by the National Science Foundation (1443263, 1443276, 1443306, 0538630, 0944343, 1043681 and 1559691) and a Poh-Hsi Pan Postdoctoral Fellowship from Rice University.
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Read the Science Advances paper, “Ice core evidence for atmospheric oxygen decline since the mid-Pleistocene transition,” at https://doi.org/10.1126/sciadv.abj9341 .
High-resolution IMAGES are available for download at:
https://news-network.rice.edu/news/files/2021/12/1220_O2DROP-1951-lg.jpg
CAPTION: Yuzhen Yan in Antarctica in December 2015. (Photo courtesy of Yuzhen Yan)
https://news-network.rice.edu/news/files/2021/12/1220_O2DROP-2510-lg.jpg
CAPTION: Researchers studied Earth’s ancient atmosphere by capturing tiny bubbles of air that were preserved in Antarctic ice for up to 1.5 million years. (Photo by Yuzhen Yan)
https://news-network.rice.edu/news/files/2021/12/1220_O2DROP-2512-lg.jpg
CAPTION: A scientific drilling mission to Allan Hills, East Antarctica, in 2015-16 yielded ice cores with trapped bubbles of ancient air, including some that predated the ice age that began 2.7 million years ago. (Photo by Yuzhen Yan)
IMPORTANT NOTICE
Because of COVID-19, the field trip is being postponed to later (date TBD) this year. The seminar will continue via remote meetings through the end of the Spring 2020 semester.
As earth scientists we seek to understand the natural processes that have shaped the world around us through time. The most fundamental requirement to acquiring a deeper understanding of these mechanisms is through observation. EEPS has a strong heritage in field-based research that when combined with analytical excellence, produces skilled scientists with a broad view of Earth as a system. While Rice University is well placed to take advantage of a broad array of research resources, students in Houston do not always have immediate access to nearby geological sites that represent Earth as a system.
A generous gift from Mike Johnson enables EEPS students the opportunity to observe classic and fundamental geologic concepts in the field. Students are in charge of proposing, selecting and managing a field excursion that will benefit everyone in the department. A year-long seminar-based class run by the students prepares them to visit the locality they have selected. Papers are selected, presented and discussed, followed by activities that educate the students on how to run a field-based project. During the field excursion, elected stops will be led and presented by individual students. The knowledge gained before and during the field trip will cumulate into a multi-media field guide that will be made available to the department and public following the trips conclusion.
A significant benefit of a department-wide field excursion is the interaction of students with scientists from various disciplines. Many earth scientists only carry out field work with specialists in their own field. The real discoveries in modern earth science occur when the different disciplines are part of a collective discourse. This trip will have scientists with different backgrounds observe the same outcrops; fostering fruitful discussion that results in the generation of new and unique questions. In addition, this trip may inspire fellowship among EEPS graduate students that will hopefully create life-long collaborations and a cohesive department.
General route starting in Albuquerque, New Mexico
This year, EEPS elected to utilize Mike Johnson’s gift to lead graduate students on a 7 day field expedition to observe some of the most diverse and economically important geologic terrains in the United States.
In early June of 2020, EEPS will travel through New Mexico, Colorado and Utah, which have easily accessible exposures of metamorphic, sedimentary, and igneous rocks. Starting from Albuquerque, New Mexico they will explore the Rio Grande Rift, the San Juan Volcanic field, and the well exposed Mezozoic stratigraphy on the Colorado Plateau. Observing these diverse geologic terrains will give EEPS graduate students a chance to see how their research interests dovetail with what they observe in nature and provide opportunities to create new ideas.
Pre-Trip planning seminars
Fall semester: The graduate student of the winning field trip proposal organizes a weekly reading group focusing on the regional geology of the four corners region and come up with potential stops.
Spring semester: The weekly reading group continues. Students pick the final outcrops that they would like to visit. Each student is assigned to be an expert on 1-3 stops. Before the field trip, each student will submit their description(s) of their stop for the field guide.