A Star Became 1,000 Times Brighter, and Now Astronomers Know Why

Artist’s impression of one of the two stars in the FU Orionis binary system, surrounded by an accreting disk of material. What has caused this star — and others like it — to dramatically brighten? [NASA/JPL-Caltech]
Artist’s impression of one of the two stars in the FU Orionis binary system, surrounded by an accreting disk of material. Credit: NASA/JPL-Caltech

Astronomers were surprised in 1937 when a star in a binary pair suddenly brightened by 1,000 times. The pair is called FU Orionis (FU Ori), and it’s in the constellation Orion. The sudden and extreme variability of one of the stars has resisted a complete explanation, and since then, FU Orionis has become the name for other stars that exhibit similar powerful variability.

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If Europa has Geysers, They’re Very Faint

Jupiter's second Galilean moon, Europa. Its smooth surface has fewer craters than other moons, but they help us understand its icy shell. (Credit: NASA/JPL/Galileo spacecraft)
The Hubble spotted evidence of geysers coming from Jupiter's moon Europa, but nobody's been able to find them again. (Credit: NASA/JPL/Galileo spacecraft)

In 2013, the Hubble Space Telescope spotted water vapour on Jupiter’s moon Europa. The vapour was evidence of plumes similar to the ones on Saturn’s moon Enceladus. That, and other compelling evidence, showed that the moon has an ocean. That led to speculation that the ocean could harbour life.

But the ocean is obscured under a thick, global layer of ice, making the plumes our only way of examining the ocean. The plumes are so difficult to detect they haven’t been confirmed.

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Astronomers Propose a 50-Meter Submillimeter Telescope

The Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile is our most powerful radio telescope. But astronomers are hungering for a new radio telescope made of one massive dish. Image Credit: A. Marinkovic/X-Cam/ALMA (ESO/NAOJ/NRAO)

Some parts of the Universe only reveal important details when observed in radio waves. That explains why we have ALMA, the Atacama Large Millimetre-submillimetre Array, a collection of 7-meter and 12-meter radio telescopes that work together as an interferometer. But, ALMA-type arrays have their limitations, and astronomers know what they need to overcome those limitations.

They need a radio telescope that’s just one single, massive dish.

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Astronomers Image 62 Newly-Forming Planetary Systems

Planet-forming discs in three clouds of the Milky Way. Credit: ESO.

Astronomers using the Very Large Telescope in Chile have now completed one of the largest surveys ever to hunt for planet-forming discs. They were able to find dozens of dusty regions around young stars, directly imaging the swirling gas and dust which hints at the locations of these new worlds.

Just like the wide variety in the types of exoplanets that have been discovered, these new data and stunning images show how protoplanetary systems are surprisingly diverse, with different sizes and shapes of disks.

In research presented in three new papers, researchers imaged 86 young stars and found 62 of them had a wide range of star-forming regions surrounding them. The astronomers say this study provides a wealth of data and unique insights into how planets arise in different regions of our galaxy.

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Astronomers See Massive Stars Forming Together in Multiple Star Systems

This false-color image of the massive star formation region G333.23–0.06 came from data obtained with the ALMA radio observatory. The insets show regions where researchers detected multiple systems of protostars. The star symbols indicate the location of each newly forming star. Image Credit: S. Li, MPIA / J. Neidel, MPIA Graphics Department / Data: ALMA Observatory

All stars form in giant molecular clouds of hydrogen. But some stars are extraordinarily massive; the most massive one we know of is about 200 times more massive than the Sun. How do these stars gain so much mass?

Part of the answer is that they form in multiple star systems.

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The Youngest Planetary Disks Ever Seen

The evolutionary sequence of protoplanetary disks with substructures, from the ALMA CAMPOS survey. These wide varieties of planetary disk structures are possible formation sites for young protoplanets. Image Credit: Hsieh et al. in prep.

How long does planet formation take? Maybe not as long as we thought, according to new research. Observations with the Atacama Large Millimetre/submillimetre Array (ALMA) show that planet formation around young stars may begin much earlier than scientists thought.

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Young Stars in the Outskirts of Galaxies Finally Have an Explanation

Star formation is well understood when it happens in the populous centers of galaxies. From our vantage point on Earth, within the Milky Way, we see it happening all around us. But when newborn stars are birthed in the empty outskirts of galactic space, it requires a new kind of explanation. At the 243rd meeting of the American Astronomical Association yesterday, astronomers announced that they have observed, for the first time, the unique molecular clouds that give rise to star formation near the remote edges of galaxies.

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The Oldest Known Spiral Galaxy Has Ripples Like the Surface of a Pond

This simulation illustrates a galaxy disk being disturbed, leading to the propagation of a seismic ripple throughout the disk. (Credit: Bland-Hawthorn and Tepper-Garcia, University of Sydney).

Astronomers have detected pond-like ripples across the gaseous disk of an ancient galaxy. What caused the ripples, and what do they tell us about the distant galaxy’s formation and evolution? And whatever happened, how has it affected the galaxy and its main job: forming stars?

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ALMA Takes Next-Level Images of a Protoplanetary Disk

This ALMA image of the young star HL Tauri shows rings of dust surrounding the star. The line patterns show the orientation of polarized light. It's the deepest dust polarization image of any protoplanetary disk captured thus far, revealing details about the dust grains in the disk. Credit: NSF/AUI/NRAO/B. Saxton/Stephens et al.

The ESO’s Atacama Large Millimeter/submillimeter Array (ALMA) is perched high in the Chilean Andes. ALMA is made of 66 high-precision antennae that all work together to observe light just between radio and infrared. Its specialty is cold objects, and in recent years, it has taken some stunning and scientifically illuminating images of protoplanetary disks and the planets forming in them.

But its newest image supersedes them all.

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Sometimes Compact Galaxies Hide Their Black Holes

Illustration of an active quasar. What role does its dark matter halo play in activating the quasar? Credit: ESO/M. Kornmesser
Illustration of an active quasar. New research shows that SMBHs eat rapidly enough to trigger them. Credit: ESO/M. Kornmesser

Quasars, short for quasi-stellar objects, are one of the most powerful and luminous classes of objects in our Universe. A subclass of active galactic nuclei (AGNs), quasars are extremely bright galactic cores that temporarily outshine all the stars in their disks. This is due to the supermassive black holes in the galactic cores that consume material from their accretion disks, a donut-shaped ring of gas and dust that orbit them. This matter is accelerated to close to the speed of light and slowly consumed, releasing energy across the entire electromagnetic spectrum.

Based on past observations, it is well known to astronomers that quasars are obscured by the accretion disk that surrounds them. As powerful radiation is released from the SMBH, it causes the dust and gas to glow brightly in visible light, X-rays, gamma-rays, and other wavelengths. However, according to a new study led by researchers from the Centre for Extragalactic Astronomy (CEA) at Durham University, quasars can also be obscured by the gas and dust of their entire host galaxies. Their findings could help astronomers better understand the link between SMBHs and galactic evolution.

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