Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Zooming in on an Infant Solar System

11.06.2010
For the first time, astronomers have observed solar systems in the making in great detail.

A team led by University of Arizona astronomer Joshua Eisner has observed in unprecedented detail the processes giving rise to stars and planets in nascent solar systems.

The discoveries, published in the Astrophysical Journal (available online at http://xxx.lanl.gov/abs/1006.1651), provide a better understanding of the way hydrogen gas from the protoplanetary disk is incorporated into the star.

By coupling both Keck telescopes on Mauna Kea in Hawaii with a specifically engineered instrument named ASTRA (ASTrometric and phase-Referenced Astronomy), Eisner and his colleagues were able to peer deeply into protoplanetary disks – swirling clouds of gas and dust that feed the growing star in its center and eventually coalesce into planets and asteroids to form a solar system.

The big challenge facing Eisner's team lies in obtaining the extremely fine resolution necessary to observe the processes that happen at the boundary between the star and its surrounding disk – 500 light years from Earth. It's like standing on a rooftop in Tucson trying to observe an ant nibbling on a grain of rice in New York's Central Park.

"The angular resolution you can achieve with the Hubble Space Telescope is about 100 times too coarse to be able to see what is going on just outside of a nascent star not much bigger than our sun," said Eisner, an assistant professor at UA's Steward Observatory. In other words, even a protoplanetary disk close enough to be considered in the neighborhood of our solar system would appear as a featureless blob.

Combining the light from the two Keck telescopes provides an angular resolution finer than Hubble's. Eisner and his team used a technique called spectro-astrometry to boost resolution even more. By measuring the light emanating from the protoplanetary disks at different wavelengths with both Keck telescope mirrors and manipulating it further with ASTRA, the researchers achieved the resolution needed to observe processes in the centers of the nascent solar systems.

Protoplanetary disks form in stellar nurseries when clouds of gas molecules and dust particles begin to collapse under the influence of gravity.

Initially rotating slowly, the cloud's growing mass and gravity cause it to become more dense and more compact. The preservation of rotational momentum speeds up the cloud as it shrinks, much like a figure skater spins faster as she tugs in her arms. The centrifugal force flattens the cloud into a spinning disk of swirling gas and dust, eventually giving rise to planets orbiting their star in roughly the same plane.

Combining the Keck interferometer with the spectro-astrometry technique, Eisner and his collaborators were able to distinguish between the distributions of gas, mostly made up of hydrogen, and dust, thereby resolving the disk's features.

"We were able to get really, really close to the star and look right at the interface between the gas-rich protoplanetary disk and the star," said Eisner, who serves as project scientist on the ASTRA team.

Astronomers know that stars acquire mass by incorporating some of the hydrogen gas in the disk that surrounds them, in a process called accretion.

"We want to understand how material accretes onto the star," Eisner said. "This process has never been measured directly."

Accretion can happen in one of two ways.

In one scenario, gas is swallowed as it washes up right to the fiery surface of the star.

In the second, much more violent scenario, the magnetic fields sweeping from the star push back the approaching gas and cause it to bunch up, creating a gap between the star and its surrounding disk. Rather than lapping at the star's surface, the hydrogen atoms travel along the magnetic field lines as if on a highway, becoming super-heated and ionized in this process.

"Once trapped in the star's magnetic field, the gas is being funneled along the field lines arching out high above and below the disk's plane," Eisner explained. "The material then crashes into the star's polar regions at high velocities."

In this inferno, which releases the energy of millions of Hiroshima-sized atomic bombs every second, some of the arching gas flow is ejected from the disk and spews out far into space as interstellar wind.

Eisner's team pointed the telescopes at 15 protoplanetary disks with young stars varying in mass between one half and 10 times that of our sun. This sample of disks, all located in our own galaxy, the Milky Way, represents by far the largest of its kind.

"We could successfully discern that in most cases, the gas converts some of its kinetic energy into light very close to the stars" he said, a tell-tale sign of the more violent accretion scenario.

"In other cases, we saw evidence of winds launched into space together with material accreting on the star," Eisner added. "We even found an example – around a very high-mass star – in which the disk may reach all the way to the stellar surface."

The solar systems the astronomers chose for this study are still young, probably a few million years old.

"These disks will be around for a few million years more," Eisner said. "By that time, the first planets, gas giants similar to Jupiter and Saturn, may form, using up a lot of the disk material."

More solid, rocky planets like the Earth, Venus or Mars, won't be around until much later.

"But the building blocks for those could be forming now," he said, which is why this research is important for our understanding of how solar systems form, including those with potentially habitable planets like Earth.

"We are going to see if we can make similar measurements of organic molecules and water in protoplanetary disks," he said. "Those would be the ones potentially giving rise to planets with the conditions to harbor life."

Eisner's co-authors on the paper are John Monnier from the University of Michigan; Julien Woillez, Sam Ragland and Peter Wizinowich from Keck Observatory; Rachel Akeson and Rafael Millan-Gabet from NASA's Exoplanet Science Institute at Caltech; James Graham at the University of California Berkeley; Lynne Hillenbrand from Caltech's Astrophysics department; and Joerg-Uwe Pott from the Max-Planck-Institut fuer Astronomie in Heidelberg, Germany.

The ASTRA project was made possible by a Major Research Instrumentation Grant from the National Science Foundation.

Reference: (available online at http://xxx.lanl.gov/abs/1006.1651) Eisner et al. Spatially and Spectrally Resolved Hydrogen Gas within 0.1 AU of T Tauri and Herbig Ae/Be Stars. Astrophysical Journal Vol. 718, July 20, 2010 (scheduled)

Daniel Stolte | University of Arizona
Further information:
http://www.arizona.edu
http://xxx.lanl.gov/abs/1006.1651

More articles from Physics and Astronomy:

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

nachricht Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>