Physics and astronomy Archives - News@91��ɫ

91��ɫ U led research sheds light on earliest days of Earth’s formation

egamulin — Wed, 26 Mar 2025 16:34:59 +0000

Faculty of Science prof used novel approach of applying fluid dynamics and chemistry to planetary sciences for modelling study published in Nature

Wednesday March 26, TORONTO – New research led by a 91��ɫ professor sheds light on the earliest days of the Earth’s formation and potentially calls into question some earlier assumptions in planetary science about the early years of rocky planets. Establishing a direct link between the Earth’s interior dynamics occurring within the first 100 million years of its history and its present-day structure, the work is one of the first in the field to combine fluid mechanics with chemistry to better understand the Earth's early evolution.

“This study is the first to demonstrate, using a physical model, that the first-order features of Earth’s lower mantle structure were established four billion years ago, very soon after the planet came into existence,” says lead author Faculty of Science Assistant Professor in the Department of Physics and Astronomy at 91��ɫ.

The mantle is the rocky envelopment that surrounds the iron core of rocky planets. The structure and dynamics of the Earth’s lower mantle play a major role throughout Earth’s history as it dictates, among others, the cooling of the Earth’s core where the Earth’s magnetic field is generated.

Boukaré – originally from France – worked with research colleagues from his former institution, Université Paris Cité's James Badro and Henri Samuel, on the paper, , which was published today in Nature.

Boukaré says that while seismology, geodynamics, and petrology have helped answer many questions about the present-day thermochemical structure of Earth’s interior, a key question remained: how old are these structures, and how did they form? Trying to answer this, he says, is much like looking at a person in the form of an adult versus a child and understanding how the energetic conditions will not be the same.

Artistic view of Earth’s interior during mantle solidification in the first hundreds of millions of years of Earth’s history. Gravitational segregation of dense, iron-rich magma (in orange) likely formed a basal magma ocean atop the core, that can explain the present-day structure of the lower mantle.

“If you take kids, sometimes they do crazy things because they have a lot of energy, like planets when they are young. When we get older, we don't do as many crazy things, because our activity or level of energy decreases. So, the dynamic is really different, but there are some things that we do when we are really young that might affect our entire life,” he says “It’s the same thing for planets. There are some aspects of the very early evolution of planets that we can actually see in their structure today.”

To better understand old planets, we must first learn how young planets behave.

Since simulations of the Earth’s mantle focus mostly on present-day solid-state conditions, Boukaré had to develop a novel model to explore the early days of Earth when the mantle was much hotter and substantially molten, work that he has been doing since his PhD.

Boukaré’s model is based on a multiphase flow approach that allows for capturing the dynamics of magma solidification at a planetary scale. Using his model, he studied how the early mantle transitioned from a molten to a solid state. Boukaré and his team were surprised to discover that most of the crystals formed at low pressure, which he says creates a very different chemical signature than what would be produced at depth in a high-pressure environment. This challenges the prevailing assumptions in planetary sciences in how rocky planets solidify.

“Until now, we assumed the geochemistry of the lower mantle was probably governed by high-pressure chemical reactions, and now it seems that we need to account also for their low-pressure counterparts.”

Boukare says this work could also help predict the behaviour of other planets down the line.

“If we know some kind of starting conditions, and we know the main processes of planetary evolution, we can predict how planets will evolve.”

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91��ɫ is a modern, multi-campus, urban university located in Toronto, Ontario. Backed by a diverse group of students, faculty, staff, alumni and partners, we bring a uniquely global perspective to help solve societal challenges, drive positive change, and prepare our students for success. 91��ɫ's fully bilingual Glendon Campus is home to Southern Ontario's Centre of Excellence for French Language and Bilingual Postsecondary Education. 91��ɫ’s campuses in Costa Rica and India offer students exceptional transnational learning opportunities and innovative programs. Together, we can make things right for our communities, our planet, and our future.

Media Contact:

Emina Gamulin, 91��ɫ Media Relations, 437-217-6362, egamulin@yorku.ca

The post 91��ɫ U led research sheds light on earliest days of Earth’s formation appeared first on News@91��ɫ.

Black hole wind is speeding up, new study finds

egamulin — Tue, 11 Jun 2024 18:15:05 +0000

Work by 91��ɫ astronomer and research colleagues in U.S. may provide clues into development of surrounding galaxies

TORONTO, June 11 2024 - Clouds of gas in a distant galaxy are being pushed faster and faster out among neighbouring stars by blasts of radiation from the supermassive black hole at the galaxy’s centre, a discovery that helps illuminate the way active black holes can continuously shape their galaxies by spurring on or snuffing out the development of new stars.

An image showing the intensity of light for the entire set of 130 spectra used in this study. Warmer or redder colours indicate more light, and bluer or cooler colours represent less light. Credit: Robert Wheatley, Catherine Grier and the SDSS collaboration

A team of researchers, including 91��ɫ Faculty of Science Professor and Physics and Astronomy Chair , revealed the accelerating gas through years of observations of a quasar — a black hole surrounded by a hot and bright disk of matter — some 30 billion light years away in the constellation Boötes.

Hall says that while this quasar acceleration has been seen before, including by researchers involved in this study, the level of detail here is unprecedented.

“We were able to make 130 observations over the course of eight years, so our confidence in this acceleration is quite high,” says Hall. “The difference in information could be compared to looking at two photographs at different points in time versus a movie.”

Black holes are believed to be situated at the centre of most galaxies. Quasars are supermassive black holes surrounded by disks of matter being pulled in by the black hole’s enormous gravitational power.

The research was led by University of Wisconsin–Madison astronomy professor Catherine Grier and recent graduate Robert Wheatley, and also included researchers from Pennsylvania State University, the University of Arizona, and others. and the findings are also being presented today at the 244th meeting of the American Astronomical Society.

“The material in that disk is always falling into the black hole, and the friction it feels heats up the disk and makes it very, very hot and very, very bright,” says Grier. “These quasars are really luminous and — because there’s a large range of temperatures from the interior to the far parts of the disk — their emission covers almost all of the electromagnetic spectrum.”

91��ɫ Astronomy Prof. Patrick Hall

The bright light makes visible quasars nearly as old as the universe (and as many as 13 billion light years away when their light was emitted), and the broad range of their radiation makes them particularly useful for astronomers to probe the early universe.

Researchers used more than eight years of observations of a quasar called SBS 1408+544, collected by a quasar monitoring program carried out by the now known as the Black Hole Mapper Reverberation Mapping Project. They tracked winds composed of gaseous carbon by spotting light from the quasar that was missing — light that was being absorbed by the gas. But instead of being absorbed at exactly the right spot in the spectrum that would indicate carbon, the shadow shifted farther from home with every new look.

“That shift tells us the gas is moving fast, and faster all the time,” says Wheatley. “We think the wind is accelerating because it’s being pushed by radiation that is blasted off of the accretion disk.”

The winds pushing gas out from the quasar are of interest to astronomers because they are a way in which the supermassive black holes might influence the evolution of the galaxies that surround them.

Depending on the circumstances, a quasar’s winds could supply pressure that squeezes gas together and speeds the birth of stars in its host galaxy. Or it could scour away that fuel and keep potential stars from forming.

To study quasars, astronomers look at their spectra, which is a measure of how much light the quasar gives off at each wavelength — from ultraviolet through the full visible spectrum from blue to red, and into infrared. A spectrum can reveal far more about a quasar than a simple telescope image — so by repeatedly measuring spectra over many years, astronomers can watch quasar light fluctuations and learn about the motion of the gas in the accretion disk, which can be used to determine the mass.

“Light has a force, so if you shine enough light on an object it can move,” says Hall. “We think that may be what's going on here, but it's not clear because I don't think we see enough of an increase in light to explain the acceleration we see. It's possible that wavelengths of ultraviolet light that we can’t observe directly are responsible, but right now it’s not clear. I look forward to seeing what this quasar does in the future.”

About 91��ɫ

91��ɫ is a modern, multi-campus, urban university located in Toronto, Ontario. Backed by a diverse group of students, faculty, staff, alumni and partners, we bring a uniquely global perspective to help solve societal challenges, drive positive change, and prepare our students for success. 91��ɫ’s fully bilingual Glendon Campus is home to Southern Ontario’s Centre of Excellence for French Language and Bilingual Postsecondary Education. 91��ɫ’s campuses in Costa Rica and India offer students exceptional transnational learning opportunities and innovative programs. Together, we can make things right for our communities, our planet, and our future.

Media Contacts: Emina Gamulin, 91��ɫ Media Relations and External Communications, 437-217-6362, egamulin@yorku.ca

The post Black hole wind is speeding up, new study finds appeared first on News@91��ɫ.