The setting Sun dips below the horizon of the Pacific Ocean, bathing the Paranal platform in light in this amazing aerial image from the Atacama Desert in northern Chile. The Cerro Paranal mountain top is home to the world’s most advanced ground-based facility for astronomy, hosting the four 8.2-metre Unit Telescopes of the Very Large Telescope, four 1.8-metre Auxiliary Telescopes and the VLT Survey Telescope (VST) — all of which are visible in this image. The 4.1-metre Visible and Infrared Survey Telescope for Astronomy (VISTA), also housed at Cerro Paranal, is hidden out of frame.
When it comes to telescopes, bigger really is better. A larger telescope brings with it the ability to see fainter objects and also to be able to see more detail. Typically we have relied upon larger and larger single aperture telescopes in our attempts to distinguish exoplanets around other stars. Space telescopes have also been employed but all that may be about to change. A new paper suggests that multiple telescopes working together as interferometers are what’s needed.
Image of radio telescopes at the Karl G. Jansky Very Large Array, located in Socorro, New Mexico. (Credit: National Radio Astronomy Observatory)
Universe Today has investigated the significance of studying impact craters, planetary surfaces, exoplanets, astrobiology, solar physics, comets, planetary atmospheres, planetary geophysics, cosmochemistry, and meteorites, and how these scientific fields contribute to researchers and the public gain greater insight into our place in the universe and finding life beyond Earth. Here, will discuss the field of radio astronomy with Dr. Wael Farah, who is a research scientist at the SETI Institute, about how radio astronomy teaches us about the myriad of celestial objects that populate our universe, along with the benefits and challenges, finding life beyond Earth, and how upcoming students can pursue studying radio astronomy. But what is radio astronomy and why is it so important to study?
Artist’s concept of one of brightest explosions ever seen in space: a Luminous Fast Blue Optical Transient (LFBOT). Credit: NASA
While the night sky may appear tranquil (and incredibly beautiful), the cosmos is filled with constant stellar explosions and collisions. Among the rarest of these transient events are what is known as Luminous Fast Blue Optical (LFBOTs), which shine intensely bright in blue light and fade after a few days. These transient events are only detectable by telescopes that continually monitor the sky. Using the venerable Hubble Space Telescope, an international team of astronomers recently observed an LFBOT far between two galaxies, the last place they expected to see one.
NASA scientists used microwave observations to spot the first polar cyclone on Uranus, seen here as a light-colored dot to the right of center in each image of the planet. The images use wavelength bands K, Ka, and Q, from left. To highlight cyclone features, a different color map was used for each. Credit: NASA/JPL-Caltech/VLA.
Uranus takes 84 years to orbit the Sun, and so that last time that planet’s north polar region was pointed at Earth, radio telescope technology was in its infancy.
But now, scientists have been using radio telescopes like the Very Large Array (VLA) the past few years as Uranus has slowly revealing more and more of its north pole. VLA microwave observations from 2021 and 2022 show a giant cyclone swirling around this region, with a bright, compact spot centered at Uranus’ pole. Data also reveals patterns in temperature, zonal wind speed and trace gas variations consistent with a polar cyclone.
Originally predicted by Einstein’s Theory of General Relativity, black holes are the most extreme object in the known Universe. These objects form when stars reach the end of their life cycle, blow off their outer layers, and are so gravitationally powerful that nothing (not even light) can escape their surfaces. They are also of interest because they allow astronomers to observe the laws of physics under the most extreme conditions. Periodically, these gravitational behemoths will devoir stars and other objects in their vicinity, releasing tremendous amounts of light and radiation.
In October 2018, astronomers witnessed one such event when observing a black hole in a galaxy located 665 million light-years from Earth. While astronomers have witnessed events like this before, another team from the Harvard & Smithsonian Center for Astrophysics noticed something unprecedented when they examined the same black hole three years later. As they explained in a recent study, the black hole was shining very brightly because it was ejecting (or “burping”) leftover material from the star at half the speed of light. Their findings could provide new clues about how black holes feed and grow over time.
Composite image of the Milky Way's core created by Hubble, Spitzer, and Chandra telescopes. Credit X-ray: NASA/CXC/UMass/D. Wang et al.; Optical: NASA/ESA/STScI/D.Wang et al.; IR: NASA/JPL-Caltech/SSC/S.Stolovy
Roughly 13.8 billion years ago, our Universe was born in a massive explosion that gave rise to the first subatomic particles and the laws of physics as we know them. About 370,000 years later, hydrogen had formed, the building block of stars, which fuse hydrogen and helium in their interiors to create all the heavier elements. While hydrogen remains the most pervasive element in the Universe, it can be difficult to detect individual clouds of hydrogen gas in the interstellar medium (ISM).
This makes it difficult to research the early phases of star formation, which would offer clues about the evolution of galaxies and the cosmos. An international team led by astronomers from the Max Planck Institute of Astronomy (MPIA) recently noticed a massive filament of atomic hydrogen gas in our galaxy. This structure, named “Maggie,” is located about 55,000 light-years away (on the other side of the Milky Way) and is one of the longest structures ever observed in our galaxy.
Artists's conception of the central portion of the Next Generation Very Large Array.
Credit: Sophia Dagnello, NRAO/AUI/NSF
The iconic Very Large Array (VLA) in New Mexico has been at the forefront of astrophysical research since its dedication in 1980. The Y-shaped configuration of 27 radio astronomy dishes have made key discoveries about the cosmos, while becoming a part of pop-culture in several high-profile movies.
But the aging array is due for an upgrade, one that would take advantage of advanced technology. So says the latest Decadal Survey, published by the U.S. National Academy of Sciences, which presents a consensus among researchers on the most important scientific goals and missions for the upcoming decade.
Observations using the Very Large Array (orange) reveal the needle-like trail of pulsar J0002+6216 outside the shell of its supernova remnant, shown in image from the Canadian Galactic Plane Survey. The pulsar escaped the remnant some 5,000 years after the supernova explosion. Credit: NRAO
When a star exhausts its nuclear fuel towards the end of its lifespan, it undergoes gravitational collapse and sheds its outer layers. This results in a magnificent explosion known as a supernova, which can lead to the creation of a black hole, a pulsar or a white dwarf. And despite decades of observation and research, there is still much scientists don’t know about this phenomena.
Luckily, ongoing observations and improved instruments are leading to all kinds of discoveries that offer chances for new insights. For instance, a team of astronomers with the National Radio Astronomy Observatory (NRAO) and NASA recently observed a “cannonball” pulsar speeding away from the supernova that is believed to have created it. This find is already providing insights into how pulsars can pick up speed from a supernova.
Artist's conception of SIMP J01365663+0933473, an object with 12.7 times the mass of Jupiter, but a magnetic field 200 times more powerful than Jupiter's. This object is 20 light-years from Earth. Credit: Caltech/Chuck Carter; NRAO/AUI/NSF
Rogue planets are a not-too-uncommon occurrence in our Universe. In fact, within our galaxy alone, it is estimated that there are billions of rogue planets, perhaps even more than there are stars. These objects are basically planet-mass objects that have been ejected from their respective star systems (where they formed), and now orbit the center of the Milky Way. But it is especially surprising to find one orbiting so close to our own Solar System!
In 2016, scientists detected what appeared to be either a brown dwarf or a star orbiting just 20 light years beyond our Solar System. However, using the National Science Foundation’s Karl G. Jansky Very Large Array(VLA), a team of astronomers recently concluded that it is right at the boundary between a massive planet and a brown dwarf. This, and other mysterious things about this object, represent a mystery and an opportunity to astronomers!
The study which describes their findings recently appeared the Astrophysical Journal under the title “The Strongest Magnetic Fields on the Coolest Brown Dwarfs.” The team was led by Melodie Kao – who led this study while a graduate student at Caltech, and is now a Hubble Postdoctoral Fellow at Arizona State University – and included members from Arizona State University, the University of Colorado Boulder, the California Institute of Technology, and the University of California San Diego.
To summarize, brown dwarfs are objects that are too massive to be considered planets, but not massive enough to become stars. Originally, such objects were not thought to emit radio waves, but in 2001, a team using the VLA discovered a brown dwarf that exhibited both strong radio emissions and magnetic activity. Ongoing observations also revealed that some brown dwarfs have strong auroras, similar to the gas giants in our Solar System.
This particular object, known as SIMP J01365663+0933473, was first discovered in 2016 by the Caltech team as one of five brown dwarfs. This survey was part of VLA study to gain new knowledge about magnetic fields and the mechanisms by which the coolest astronomical objects can produce strong radio emissions. Since brown dwarfs are incredibly difficult to measure, the object was initially though to be too old and too massive to be a brown dwarf.
However, last year, an independent team of scientists discovered that SIMP J01365663+0933473 was part of a very young group of stars whose age, size and mass indicated that it was likely to be a free-floating (aka. rogue) planet rather than a star. In short, the object was determined to be 200 million years old, 1.22 times the radius of Jupiter and 12.7 times its mass.
It was also estimated to have a surface temperature of about 825 °C (1500 °F) – compared to the Sun’s, which is 5,500 °C (9932 °F). Simultaneously, the Caltech team that originally detected its radio emission in 2016 observed it again in a new study at even higher radio frequencies. From this, they confirmed that its magnetic field was even stronger than first measured, roughly 200 times stronger than Jupiter’s.
As Dr. Kao explained in a recent NRAO press release, this all presents a rather mysterious find:
“This object is right at the boundary between a planet and a brown dwarf, or ‘failed star,’ and is giving us some surprises that can potentially help us understand magnetic processes on both stars and planets… When it was announced that SIMP J01365663+0933473 had a mass near the deuterium-burning limit, I had just finished analyzing its newest VLA data.”
In short, the VLA observations provided both the first radio detection and the first measurement of the magnetic field of a planetary-mass object beyond our Solar System. The presence of a such a strong magnetic field represents a huge challenge to astronomers’ understanding of the dynamo mechanisms that create magnetic fields in brown dwarfs, not to mention the mystery of what drives their auroras.
Ever since brown dwarfs were observed to have auroral activity, scientists have wondered what could be powering them. On Earth, as with Jupiter and the other Solar planets that experience them, aurorae are the result of solar wind interacting with a planet’s magnetic field. But in the case of brown dwarfs, which have no parent star, some other mechanism must be involved. As Kao explained:
“This particular object is exciting because studying its magnetic dynamo mechanisms can give us new insights on how the same type of mechanisms can operate in extrasolar planets — planets beyond our Solar System. We think these mechanisms can work not only in brown dwarfs, but also in both gas giant and terrestrial planets.”
An artist’s conception of a T-type brown dwarf. Credit: Wikipedia Commons/Tyrogthekreeper
Kao and her team think that one possibility is that this object has an orbiting planet or moon that is interacting with its magnetic field, similar to what happens between Jupiter and its moon Io. Given its proximity to our Solar System, scientists will have the opportunity to address this and other questions, and to learn a great deal about the mechanics that power gas giants and brown dwarfs.
Studying this object will also help astronomers place more accurate constraints on the dividing line between massive planets and brown dwards. And last, but not least, it also presents new opportunities as far exoplanet research is concerned. As Gregg Hallinan, who was Dr. Kao’s advisor and a co-author on the Caltech study, explained:
“Detecting SIMP J01365663+0933473 with the VLA through its auroral radio emission also means that we may have a new way of detecting exoplanets, including the elusive rogue ones not orbiting a parent star.”
Between finding planets that orbit distant stars to planetary-mass objects that orbit the center of the Milky Way, astronomers are making exciting discoveries that are pushing the boundaries of what we know about planetary formation and the different types that can exist. And with next-generation instruments coming online, they plan to learn a great deal more!
