Brrr. JWST Looks at the Coldest Brown Dwarf

Artist's illustration of a cold brown dwarf star. (Credit: NASA)

What are the atmospheric compositions of cold brown dwarf stars? This is what a recent study published in The Astronomical Journal hopes to address as an international team of researchers used NASA’s James Webb Space Telescope (JWST) to investigate the coldest known brown dwarf star, WISE J085510.83?071442.5 (WISE 0855). This study holds the potential to help astronomers better understand the compositions of brown dwarf stars, which are also known as “failed stars” since while they form like other stars, they fail to reach the necessary mass to produce nuclear fusion. So, what was the motivation behind using JWST to examine the coldest known brown dwarf star?

Continue reading “Brrr. JWST Looks at the Coldest Brown Dwarf”

This Brown Dwarf is 2,000 Degrees Hotter Than the Sun

exoplanet hot jupiter transiting its star
This artist’s impression shows an ultra-hot exoplanet as it is about to transit in front of its host star. Credit: ESO

Astronomers have discovered an intense binary star system located about 1,400 light years away. It contains a brown dwarf with 80 times the mass of Jupiter which is bound closely with an incredibly hot white dwarf star. Observations have shown the brown dwarf is tidally locked to the white dwarf, allowing the daytime surface temperatures on the brown dwarf to reach 8,000 Kelvin (7,700 Celsius, 14,000 Fahrenheit) — which is much hotter than the surface of the Sun, which is about 5,700 K (5,427 C, 9,800 F). The brown dwarf’s nightside, on the other hand, is about 6,000 degrees K cooler.

Continue reading “This Brown Dwarf is 2,000 Degrees Hotter Than the Sun”

An Astronomical First! A Radiation Belt Seen Outside the Solar System

Artist’s impression of an aurora and the surrounding radiation belt of the ultracool dwarf LSR J1835+3259. Credit: Chuck Carter/Melodie Kao/Heising-Simons Foundation)

In 1958, the first satellites launched by the United States (Explorer 1 and 3) detected a massive radiation belt around planet Earth. This confirmed something that many scientists suspected before the Space Age began: that energetic particles emanating from the Sun (solar wind) were captured and held around the planet by Earth’s magnetosphere. This region was named the Van Allen Belt in honor of University of Iowa professor James Van Allen who led the research effort. As robotic missions explored more of the Solar System, scientists discovered similar radiation belts around Jupiter, Saturn, Uranus, and Neptune.

Given the boom in extrasolar planet research, scientists have eagerly awaited the day when a Van Allen Belt would be discovered around an exoplanet. Thanks to a team of astronomers led by the University of California, Santa Cruz (UCSC) and the National Radio Astronomy Observatory (NRAO), that day may have arrived! Using the global High Sensitivity Array (HSA), the team obtained images of persistent, intense radio emissions from an ultracool dwarf star. These revealed the presence of a cloud of high-energy particles forming a massive radiation belt similar to what scientists have observed around Jupiter.

Continue reading “An Astronomical First! A Radiation Belt Seen Outside the Solar System”

The Next Generation of Telescopes Will Tell Us About the Weather on Other Worlds

This artist’s rendering shows the Extremely Large Telescope in operation on Cerro Armazones in northern Chile. The telescope is shown using lasers to create artificial stars high in the atmosphere. Image: ESO/E-ELT
This artist’s rendering shows the Extremely Large Telescope in operation on Cerro Armazones in northern Chile. The telescope is shown using lasers to create artificial stars high in the atmosphere. Image: ESO/E-ELT

The field of astronomy is about to be revolutionized, thanks to the introduction of Extremely Large Telescopes that rely on primary mirrors measuring 30 meters (or more) in diameter, adaptive optics (AO), coronographs, and advanced spectrometers. This will include the eponymously-named Extremely Large Telescope (ELT), the Giant Magellan Telescope (GMT), and the Thirty Meter Telescope (TMT). These telescopes will enable astronomers to study exoplanets using the Direct Imaging (DI) method, which will yield valuable data on the composition of their atmospheres.

According to a new study by a team of researchers from Ohio State University (OSU), these telescopes will also allow astronomers to study “ultracool objects,” like very low-mass stars (VLMs), brown dwarfs, and exoplanets. In addition to being able to visualize magnetic starspots and determine the chemical compositions of these objects, ELTs will be able to reveal details about atmospheric dynamics and cloud systems. These types of studies could reveal a wealth of information about some of the least-studied objects in our Universe and significantly aid in the search for life beyond our Solar System.

Continue reading “The Next Generation of Telescopes Will Tell Us About the Weather on Other Worlds”

NASA Provides a Timelapse Movie Showing How the Universe Changed Over 12 Years

This mosaic is composed of images covering the entire sky, taken by the Wide-field Infrared Survey Explorer (WISE) as part of WISE’s 2012 All-Sky Data Release. By observing the entire sky, WISE can search for faint objects, like distant galaxies, or survey groups of cosmic objects. Credits: NASA/JPL-Caltech/UCLA

The Universe is over 13 billion years old, so a 12-year slice of that time might seem uneventful. But a timelapse movie from NASA shows how much can change in just over a decade. Stars pulse, asteroids follow their trajectories, and distant black holes flare as they pull gas and dust toward themselves.

Continue reading “NASA Provides a Timelapse Movie Showing How the Universe Changed Over 12 Years”

The Moons of Rogue Planets Could Have Liquid Surface Water and Thick Atmospheres. They Could be Habitable

Artist's rendering of an Earth-sized rogue planet approaching a star. Credit: Christine Pulliam (CfA)

The search for life on exoplanets takes a fairly conservative approach. It focuses on life that is similar to that of Earth. Sure, it’s quite possible that life comes in many exotic forms, and scientists have speculated about all the strange forms life might take, but the simple fact is that Earth life is the only form we currently understand. So most research focuses on life forms that, like us, are carbon based with a biology that relies on liquid water. But even with that narrow view, life could still be hiding in places we don’t expect.

Continue reading “The Moons of Rogue Planets Could Have Liquid Surface Water and Thick Atmospheres. They Could be Habitable”

Jupiter Could Make an Ideal Dark Matter Detector

NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill (wikimedia commons)

So, you want to find dark matter, but you don’t know where to look? A giant planet might be exactly the kind of particle detector you need! Luckily, our solar system just happens to have a couple of them available, and the biggest and closest is Jupiter. Researchers Rebecca Leane (Stanford) and Tim Linden (Stockholm) released a paper this week describing how the gas giant just might hold the key to finding the elusive dark matter.

Continue reading “Jupiter Could Make an Ideal Dark Matter Detector”

Nancy Grace Roman Telescope is Getting an Upgraded new Infrared Filter

NASA’s Wide Field Infrared Survey Telescope (WFIRST) is now named the Nancy Grace Roman Space Telescope, after NASA’s first Chief of Astronomy. Credits: NASA

In 2025, the Nancy Grace Roman space telescope will launch to space. Named in honor of NASA’s first chief astronomer (and the “Mother of Hubble“), the Roman telescope will be the most advanced and powerful observatory ever deployed. With a camera as sensitive as its predecessors, and next-generation surveying capabilities, Roman will have the power of “One-Hundred Hubbles.”

In order to meet its scientific objectives and explore some of the greatest mysteries of the cosmos, Roman will be fitted with a number of infrared filters. But with the decision to add a new near-infrared filter, Roman will exceed its original design and be able to explore 20% of the infrared Universe. This opens the door for exciting new research and discoveries, from the edge of the Solar System to the farthest reaches of space.

Continue reading “Nancy Grace Roman Telescope is Getting an Upgraded new Infrared Filter”

Astronomers Measure the Wind Speed on a Brown Dwarf for the First Time. Spoiler: Insanely Fast

This artist's conception illustrates the brown dwarf named 2MASSJ22282889-431026, observed by NASA's Hubble and Spitzer space telescopes. Brown dwarfs are more massive and hotter than planets but lack the mass required to become stars. Image credit: NASA
This artist's conception illustrates the brown dwarf named 2MASSJ22282889-431026, observed by NASA's Hubble and Spitzer space telescopes. Brown dwarfs are more massive and hotter than planets but lack the mass required to become stars. Image credit: NASA

In some ways, brown dwarfs are nature’s stellar oddballs. A lot of stars exhibit strange behaviour at different times in their evolution. But brown dwarfs aren’t even certain that they’re stars at all.

But that doesn’t mean astronomers don’t want to study and understand them.

Continue reading “Astronomers Measure the Wind Speed on a Brown Dwarf for the First Time. Spoiler: Insanely Fast”

Strange Loner Planet Gets Astronomers’ Attention

Artist’s impression of the free-floating object known as CFBDSIR J~214947.2-040308.9. Credit: ESO/L. Calçada/P. Delorme/R. Saito/VVV Consortium.

In the hunt for exoplanets, some rather strange discoveries have been made. Beyond our Solar System, astronomers have spotted gas giants and terrestrial planets that appear to be many orders of magnitude larger than what we are used to (aka. “Super-Jupiters” and “Super-Earths”). And in some cases, it has not been entirely clear what our instruments have been detecting.

For instance, in some cases, astronomers have not been sure if an exoplanet candidate was a super-Jupiter or a brown dwarf. Not only do these substellar-mass stars fall into the same temperature range as massive gas giants, they also share many of the same physical properties. Such was the conundrum addressed by an international team of scientists who recently conduced a study of the object known as CFBDSIR 2149-0403.

Located between 117 and 143 light-years from Earth, this mysterious object is what is known as a “free-floating planetary mass object”. It was originally discovered in 2012 by a team of French and Canadian astronomers led by Dr. Phillipe Delorme of the University Grenoble Alpes using the Canada-France Brown Dwarfs Survey – a near infrared sky survey with the Canada-France Hawaii Telescope at Mauna Kea.

The Canada France Hawaii Telescope, near the summit of Mauna Kea, Hawaii. Credit: cfht.hawaii.edu/

The existence of this object was then confirmed using data by the Wide-field Infrared Survey Explorer (WISE), and was believed at the time to be part of a group of stars known as the AB Doradus Moving Group (30 stars that are moving through space). The data collected on this object placed its mass at between 4 and 7 Jupiter masses, its age at 20 to 200 million years, and its surface temperature at about 650-750 K.

This was the first time that such an object had constraints placed upon its mass and age using spectral data. However, questions remained about its true nature – whether it was a low mass, high-metallicity brown dwarf or a isolated planetary mass. For the sake of their study, Delorme and the international team conducted a multi-wavelength, multi-instrument observational characterization of CFBDSIR 2149-0403.

This consisted of x-ray data from the X-Shooter instrument on the ESO’s Very Large Telescope (VLT), near-infrared data from the VLT’s Hawk-1 instrument, and infrared data from the Spitzer Space Telescope and the CFHT’s Wide-field InfraRed Camera (WIRCam). As Delorme told Tomasz Nowakowski of Phys.org:

“The X-Shooter data enabled a detailed study of the physical properties of this object. However, all the data presented in the paper is really necessary for the study, especially the follow-up to obtain the parallax of the object, as well as the Spitzer photometry. Together, they enable us to get the bolometric flux of the object, and hence constraints that are almost independent from atmosphere model assumptions.”

An artist’s conception of a T-type brown dwarf star. Credit: Wikimedia Commons/Tyrogthekreeper

From the combined data, they were able to characterize the absolute flux of the CFBDSIR 2149-0403, obtain readings on its spectrum, and even determine the radial velocity of the object. They were therefore able to determine that it not likely a member of a moving population of stars, as was previously expected.

“We now reject our initial hypothesis that CFBDSIR 2149-0403 would be a member of the AB Doradus moving group,” said Delorme. “This removes the most robust age constraint we had. Though determining that certainly improved our knowledge of the object it also made it more difficult to study, by adding age as a free parameter.”

As for what it is, they narrowed that down to one of two possibilities. Basically, it could be a planetary-mass object with a mass of between 2 and 13 Jupiters that is less than 500 million years in age, or a high metallicity brown dwarf that is between 2 and 40 Jupiter masses and two to three billion years in age. Ultimately, they acknowledge that this uncertainty is due to the fact that our theoretical understanding of cool, low-gravity, and metallicity-enhanced bodies is not robust enough yet.

Much of this has to do with the fact that brown dwarfs and super gas giants have common physical parameters that produce very similar effects in the spectra of their atmospheres. But as astronomers gain more of an understanding of planetary formation, which is made possible by the discovery of so many extra-solar planetary systems, we might just find where the line between the smallest of stars and the largest of gas giants is drawn.

Further Reading: arXiv, Phys.org