Login with your Social Account

Newly Discovered Giant Planet Slingshots Around Its Star

Newly Discovered Giant Planet Slingshots Around Its Star

Astronomers have discovered a planet three times the mass of Jupiter that travels on a long, egg-shaped path around its star. If this planet were somehow placed into our own solar system, it would swing from within our asteroid belt to out beyond Neptune. Other giant planets with highly elliptical orbits have been found around other stars, but none of those worlds were located at the very outer reaches of their star systems like this one.

“This planet is unlike the planets in our solar system, but more than that, it is unlike any other exoplanets we have discovered so far,” says Sarah Blunt, a Caltech graduate student and first author on the new study publishing in The Astronomical Journal. “Other planets detected far away from their stars tend to have very low eccentricities, meaning that their orbits are more circular. The fact that this planet has such a high eccentricity speaks to some difference in the way that it either formed or evolved relative to the other planets.”

The planet was discovered using the radial velocity method, a workhorse of exoplanet discovery that detects new worlds by tracking how their parent stars “wobble” in response to gravitational tugs from those planets. However, analyses of these data usually require observations taken over a planet’s entire orbital period. For planets orbiting far from their stars, this can be difficult: a full orbit can take tens or even hundreds of years.

The California Planet Search, led by Caltech Professor of Astronomy Andrew W. Howard, is one of the few groups that watches stars over the decades-long timescales necessary to detect long-period exoplanets using radial velocity. The data needed to make the discovery of the new planet were provided by the two observatories used by the California Planet Search—the Lick Observatory in Northern California and the W. M. Keck Observatory in Hawaii—and by the McDonald Observatory in Texas.

The astronomers have been watching the planet’s star, called HR 5183, since the 1990s, but do not have data corresponding to one full orbit of the planet, called HR 5183 b, because it circles its star roughly every 45 to 100 years. The team instead found the planet because of its strange orbit.

“This planet spends most of its time loitering in the outer part of its star’s planetary system in this highly eccentric orbit, then it starts to accelerate in and does a slingshot around its star,” explains Howard. “We detected this slingshot motion. We saw the planet come in and now it’s on its way out. That creates such a distinctive signature that we can be sure that this is a real planet, even though we haven’t seen a complete orbit.”

The new findings show that it is possible to use the radial velocity method to make detections of other far-flung planets without waiting decades. And, the researchers suggest, looking for more planets like this one could illuminate the role of giant planets in shaping their solar systems.

Planets take shape out of disks of material left over after stars form. That means that planets should start off in flat, circular orbits. For the newly detected planet to be on such an eccentric orbit, it must have gotten a gravitational kick from some other object. The most plausible scenario, the researchers propose, is that the planet once had a neighbor of similar size. When the two planets got close enough to each other, one pushed the other out of the solar system, forcing HR 5183 b into a highly eccentric orbit.

“This newfound planet basically would have come in like a wrecking ball,” says Howard, “knocking anything in its way out of the system.”

This discovery demonstrates that our understanding of planets beyond our solar system is still evolving. Researchers continue to find worlds that are unlike anything in our solar system or in solar systems we have already discovered.

“Copernicus taught us that Earth is not the center of the solar system, and as we expanded into discovering other solar systems of exoplanets, we expected them to be carbon copies of our own solar system,” Howard explains, “But it’s just been one surprise after another in this field. This newfound planet is another example of a system that is not the image of our solar system but has remarkable features that make our universe incredibly rich in its diversity.”

The study, titled, “Radial Velocity of an Eccentric Jovian World Orbiting at 18AU,” was funded by the National Science Foundation, NASA, Tennessee State University and the State of Tennessee, the Beatrice Watson Parrent Fellowship, the Trottier Family Foundation, and Caltech. Other Caltech authors include: BJ Fulton, a staff scientist at IPAC; former postdoctoral scholar Sean Mills (BS ’12); Erik Petigura, a former postdoctoral scholar now based at UCLA; and Arpita Roy, R.A. & G.B. Millikan Postdoctoral Scholar in Astronomy.

Materials provided by California Institute of Technology

TESS satellite uncovers its ‘first nearby super-Earth’

TESS satellite uncovers its ‘first nearby super-Earth’

An international team of astronomers led by Cornell’s Lisa Kaltenegger has characterized the first potentially habitable world outside of our own solar system.

Located about 31 light-years away, the super-Earth planet – named GJ 357 d – was discovered in early 2019 owing to NASA’s Transiting Exoplanet Survey Satellite (TESS), a mission designed to comb the heavens for exoplanets, according to their new modeling research in the Astrophysical Journal Letters.

“This is exciting, as this is TESS’s first discovery of a nearby super-Earth that could harbor life – TESS is a small, mighty mission with a huge reach,” said Kaltenegger, associate professor of astronomy, director of Cornell’s Carl Sagan Institute and a member of the TESS science team.

The exoplanet is more massive than our own blue planet, and Kaltenegger said the discovery will provide insight into Earth’s heavyweight planetary cousins. “With a thick atmosphere, the planet GJ 357 d could maintain liquid water on its surface like Earth, and we could pick out signs of life with telescopes that will soon be online,” she said.

Astronomers from the Institute of Astrophysics of the Canary Islands and the University of La Laguna, both in Spain, announced the discovery of the GJ 357 system July 31 in the journal Astronomy & Astrophysics. They showed that the distant solar system – with a diminutive M-type dwarf sun, about one-third the size of our own sun – harbors three planets, with one of those in that system’s habitable zone: GJ 357 d.

Last February, the TESS satellite observed that the dwarf sun GJ 357 dimmed very slightly every 3.9 days, evidence of a transiting planet moving across the star’s face. That planet was GJ 357 b, a so-called “hot Earth” about 22% larger than Earth, according to the NASA Goddard Space Flight Center, which guides TESS.

Follow-up observations from the ground led to the discovery of two more exoplanetary siblings: GJ 357 c and GJ 357 d. The international team of scientists collected Earth-based telescopic data going back two decades – to reveal the newly found exoplanets’ tiny gravitational tugs on its host star, according to NASA.

Exoplanet GJ 357 c sizzles at 260 degrees Fahrenheit and has at least 3.4 times Earth’s mass. However, the system’s outermost known sibling planet – GJ 357 d, a super-Earth – could provide Earth-like conditions and orbits the dwarf star every 55.7 days at a distance about one-fifth of Earth’s distance from the sun. It is not yet known if this planet transits its sun.

Kaltenegger, doctoral candidate Jack Madden and undergraduate student Zifan Lin ’20 simulated light fingerprints, climates and remotely detectable spectra for a planet that could range from a rocky composition to a water world.

Madden explained that investigating new discoveries provides an opportunity to test theories and models. “We built the first models of what this new world could be like,” he said. “Just knowing that liquid water can exist on the surface of this planet motivates scientists to find ways of detecting signs of life.”

Lin described the work from an undergraduate perspective: “Working on a newly discovered planet is something of a dream come true. I was among the first group of people to model its spectra, and thinking about this still overwhelms me.”

In a nod to her institute’s namesake, the late Cornell professor Carl Sagan, Kaltenegger said: “If GJ 357 d were to show signs of life, it would be at the top of everyone’s travel list – and we could answer a 1,000-year-old question on whether we are alone in the cosmos.”

In addition to Kaltenegger, Madden and Lin, co-authors of “The Habitability of GJ 357d: Possible Climates and Observability,” include Sarah Rugheimer, Oxford University; Antigona Segura, National Autonomous University of Mexico (UNAM); Rafael Luque and Eric Pallé, both of the Institute of Astrophysics of the Canary Islands and the University of La Laguna; and Néstor Espinoza, Max Planck Institute for Astronomy, Germany.

Tour the GJ 357 system, located 31 light-years away in the constellation Hydra. Astronomers confirming a planet candidate identified by NASA’s Transiting Exoplanet Survey Satellite subsequently found two additional worlds orbiting the star.

Journal Reference: Astronomy & Astrophysics

Materials provided by Cornell University

TESS discovers three new planets nearby, including temperate “sub-Neptune”

TESS discovers three new planets nearby, including temperate “sub-Neptune”

NASA’s Transiting Exoplanet Survey Satellite, or TESS, has discovered three new worlds that are among the smallest, nearest exoplanets known to date. The planets orbit a star just 73 light-years away and include a small, rocky super-Earth and two sub-Neptunes — planets about half the size of our own icy giant.

The sub-Neptune furthest out from the star appears to be within a “temperate” zone, meaning that the very top of the planet’s atmosphere is within a temperature range that could support some forms of life. However, scientists say the planet’s atmosphere is likely a thick, ultradense heat trap that renders the planet’s surface too hot to host water or life.

Nevertheless, this new planetary system, which astronomers have dubbed TOI-270, is proving to have other curious qualities. For instance, all three planets appear to be relatively close in size. In contrast, our own solar system is populated with planetary extremes, from the small, rocky worlds of Mercury, Venus, Earth, and Mars, to the much more massive Jupiter and Saturn, and the more remote ice giants of Neptune and Uranus.

There’s nothing in our solar system that resembles an intermediate planet, with a size and composition somewhere in the middle of Earth and Neptune. But TOI-270 appears to host two such planets: both sub-Neptunes are smaller than our own Neptune and not much larger than the rocky planet in the system.

Astronomers believe TOI-270’s sub-Neptunes may be a “missing link” in planetary formation, as they are of an intermediate size and could help researchers determine whether small, rocky planets like Earth and more massive, icy worlds like Neptune follow the same formation path or evolve separately.

TOI-270 is an ideal system for answering such questions, because the star itself is nearby and therefore bright, and also unusually quiet. The star is an M-dwarf, a type of star that is normally extremely active, with frequent flares and solar storms. TOI-270 appears to be an older M-dwarf that has since quieted down, giving off a steady brightness, against which scientists can measure many properties of the orbiting planets, such as their mass and atmospheric composition.

“There are a lot of little pieces of the puzzle that we can solve with this system,” says Maximilian Günther, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research and lead author of a study published today in Nature Astronomy that details the discovery. “You can really do all the things you want to do in exoplanet science, with this system.”

Compare and contrast worlds in the TOI 270 system with these illustrations. Temperatures given for TOI 270 planets are equilibrium temperatures, calculated without the warming effects of any possible atmospheres. Credit: NASA’s Goddard Space Flight Center

A planetary pattern

Günther and his colleagues detected the three new planets after looking through measurements of stellar brightness taken by TESS. The MIT-developed satellite stares at patches of the sky for 27 days at a time, monitoring thousands of stars for possible transits — characteristic dips in brightness that could signal a planet temporarily blocking the star’s light as it passes in front of it.

The team isolated several such signals from a nearby  star, located 73 light years away in the southern sky. They named the star TOI-270, for the 270th “TESS Object of Interest” identified to date. The researchers used ground-based instruments to follow up on the star’s activity, and confirmed that the signals are the result of three orbiting exoplanets: planet b, a rocky super-Earth with a roughly three-day orbit; planet c, a sub-Neptune with a five-day orbit; and planet d, another sub-Neptune slightly further out, with an 11-day orbit.

Günther notes that the planets seem to line up in what astronomers refer to as a “resonant chain,” meaning that the ratio of their orbits are close to whole integers — in this case, 3:5 for the inner pair, and 2:1 for the outer pair — and that the planets are therefore in “resonance” with each other. Astronomers have discovered other small stars with similarly resonant planetary formations. And in our own solar system, the moons of Jupiter also happen to line up in resonance with each other.

“For TOI-270, these planets line up like pearls on a string,” Günther says. “That’s a very interesting thing, because it lets us study their dynamical behavior. And you can almost expect, if there are more planets, the next one would be somewhere further out, at another integer ratio.”

“An exceptional laboratory”

TOI-270’s discovery initially caused a stir of excitement within the TESS science team, as it seemed, in the first analysis, that planet d might lie in the star’s habitable zone, a region that would be cool enough for the planet’s surface to support water, and possibly life. But the researchers soon realized that the planet’s atmosphere was probably extremely thick, and would therefore generate an intense greenhouse effect, causing the planet’s surface to be too hot to be habitable.

But Günther says there is a good possibility that the system hosts other planets, further out from planet d, that might well lie within the habitable zone. Planet d, with an 11-day orbit, is about 10 million kilometers out from the star. Günther says that, given that the star is small and relatively cool — about half as hot as the sun — its habitable zone could potentially begin at around 15 million kilometers. But whether a planet exists within this zone, and whether it is habitable, depends on a host of other parameters, such as its size, mass, and atmospheric conditions.

Fortunately, the team writes in their paper that “the host star, TOI-270, is remarkably well-suited for future habitability searches, as it is particularly quiet.” The researchers plan to focus other instruments, including the upcoming James Webb Space Telescope, on TOI-270, to pin down various properties of the three planets, as well as search for additional planets in the star’s habitable zone.

“TOI-270 is a true Disneyland for exoplanet science, and one of the prime systems TESS was set out to discover,” Günther says. “It is an exceptional laboratory for not one, but many reasons — it really ticks all the boxes.”

Materials provided by Massachusetts Institute of Technology

Astronomers Have Discovered a Peculiar Rocky Exoplanet With Three Glowing Red Suns

Astronomers have discovered a strange rocky exoplanet in a triple-star system

Astronomers have recently discovered a new strange rocky Exoplanet in a triple star system. Our sun is the only star in our solar system, but out in the wider universe stars often are locked in a dance with other stars and orbit at a mutual centre of gravity.

A catchy name was allotted, LTT 1445Ab since it orbits the primary star of the three red dwarfs of system LTT 1445, located around 22.5 light-years away from earth. Astronomer Jennifer Winters of the Harvard-Smithsonian Center said that on standing on that planet’s surface, there will be three suns in the sky with two of them far away and small in size. The paper is submitted to The Astronomical Journal and can found on arXiv.

The planet was discovered by TESS, the planet-hunting space telescope of NASA which is designed to find exoplanets that pass between us and their home star by detecting the telltale dimming since the planet blocks a certain percentage of light. Scientists can place constraints on mass and size of the planet due to the depth of dimming, tiny star movements since it is slightly pulled by the gravity of planet.

The LTT 1445Ab varies from the HD131399Ab which was discovered back in 2016. It was bigger with a 550-year orbit around one of the star in a triple system 340 light-years away from earth. The new planet is only 1.35 times the size of Earth and 8.4 times Earth’s mass and thus is denser than Earth.

The size and mass put it in the category of rocky planets like Mars, Venus etc. and is not a gas or ice giant. The chances of habitability are low. The surface temperature is expected to reach scorching 428 Kelvin and it whips around its star once every 5.36 Earth days.

Astronomers predict that LTT 1445Ab might have an atmosphere like any other rocky planet and might be a good place to test the detection of gases like methane and carbon dioxide. The atmosphere dims the starlight and can also change it based on chemical composition. The atmospheric components can be found out based on the spectrum of light through the atmosphere.

The current technology is not well developed for this task but may become possible with the Hubble’s successor, the James Webb Space Telescope which will launch in 2021. LTT 1445Ab is a good candidate for observations as there will be plenty of observations and is relatively very close in a cosmic scale at a distance of 22.5 light-years away. The dwarf star is bright enough to back-light the atmosphere but not bright enough to outshine the planet. Rocky planets are relatively common in the close orbits around red dwarf stars. Hence, looking at the LTT1445Ab closer can tell us what to expect on such planets.

Journal Reference: arXiv

Teegarden’s Star and its two planets, our Solar System in the background

New Earth-like planets discovered around a very small star

An international research team led by the University of Göttingen has discovered two new Earth-like planets near one of our closest neighbouring stars. “Teegarden’s star” is only about 12.5 light years away from Earth and is one of the smallest known stars. It is only about 2,700 °C warm and about ten times lighter than the Sun. Although it is so close to us, the star wasn’t discovered until 2003. The scientists observed the star for about three years. The results were published in the journal Astronomy and Astrophysics.

Their data clearly show the existence of two planets. “The two planets resemble the inner planets of our solar system,” explains lead author Mathias Zechmeister of the Institute for Astrophysics at the University of Göttingen. “They are only slightly heavier than Earth and are located in the so-called habitable zone, where water can be present in liquid form.”

The astronomers suspect that the two planets could be part of a larger system. “Many stars are apparently surrounded by systems with several planets,” explains co-author Professor Stefan Dreizler of the University of Göttingen. Teegarden’s star is the smallest star where researchers have so far been able to measure the weight of a planet directly. “This is a great success for the Carmenes project, which was specifically designed to search for planets around the lightest stars,” says Professor Ansgar Reiners of the University of Göttingen, one of the scientific directors of the project.

Although planetary systems around similar stars are known, they have always been detected using the “transit method” — the planets have to pass visibly in front of the star and darken it for a moment, which only happens in a very small fraction of all planetary systems. Such transits have not yet been found for the new planets. But the system is located at a special place in the sky: from Teegarden’s star, you can see the planets of the solar system passing in front of the Sun.

“An inhabitant of the new planets would, therefore, have the opportunity to view the Earth using the transit method,” says Reiners. The new planets are the tenth and eleventh discovered by the team.

Carmenes is carried out by the universities of Göttingen, Hamburg, Heidelberg, and Madrid, the Max-Planck-Institut für Astronomie Heidelberg, Institutes Consejo Superior de Investigaciones Científicas in Barcelona, Granada, and Madrid, Thüringer Landessternwarte, Instituto de Astrofísica de Canarias, and Calar-Alto Observatory.

Materials provided by University of Göttingen

nasa kepler planetary system

18 Earth Sized Exoplanets detected by astronomers

Humans are always looking for traces of life beyond the Earth. They look for Earth-sized planets which may have an Earth-like atmosphere to search for traces of life. A group of researchers from Max Planck Institute for Solar System Research (MPS), the Georg August University of Göttingen, and Sonneberg Observatory have recently observed around 18 Earth-sized planets beyond the solar system. The research was published in Astronomy and Astrophysics.

Some of them are believed to have conditions suitable for life and were previously overlooked. This came to light after analyzing the data from NASA’s Kepler Space Telescope. They are expecting close to 100 more exoplanets after analyzing the data even more. There are close to 4000 planets outside our solar system and 96% are said to be bigger than our Earth. It is not accurate as smaller planets are harder to track down than bigger planets. Small world planets can be potentially habitable planets and 18 newly discovered planets are Earth-sized.

Scientists look for a transit method to look out for stars with periodically recurring faint dips in star’s light and we can observe this if a star happens to have a planet whose orbital plane is aligned with line of sight of Earth and only then the planet blocks a small fraction of light as it passes in front of the star, once per orbit.

Standard algorithms search for sudden drops in brightness but in reality, when a planet moves in front of a star it blocks less starlight than at mid-way of the transit. Maximum dimming occurs at the center of the transit. For larger planets, the dip it produces is pretty obvious, even if the algorithm is searching for a sudden dip. Thus smaller planets are difficult to differentiate from normal fluctuations of stars.

The research team has decided to test as to what may be the result if they use a more gradual light curve in detecting planets than a sudden dip in brightness. They applied the algorithm to K2 Kepler Mission which resulted in the finding of 18 new planets, however, they are found to be non-habitable as they are orbiting very close to their stars and temperatures are expected to be as high as 100-1000 degrees Celsius.

The lone exception was EPIC 201238110.02, orbiting a red dwarf, which is placed in a habitable zone which is not too hot or not too cold. Planets like these have been found before but they have their own set of problems, when orbiting a red dwarf star, they usually spew out a lot of flares and radiation which could be deadly for nearby planets. However, this is a usual observation and not always true in reality. The Kepler archive has data set for thousands of stars and the newly implemented algorithm will keep looking for new Earth-like planets.

Would you like to go to these planets in other solar system and live there? Tell us with a short and quick comment.

Read more news about exoplanets:

  1. Rare-Earth elements detected in the atmosphere of an exoplanet for the first time
  2. NASA’s TESS detects Earth-sized planet for the first time