Astronomy

Warm jupiter vs hot jupiter, fluffyness

Warm jupiter vs hot jupiter, fluffyness

If Jupiter was orbiting at 1AU, replacing Earth, but everything else in the solar system remained as it is currently, how much would the increased heat from the sun increase Jupiter's radius?

In other words, how much would Jupiter fluff up if it was closer to the sun?

Would that be close enough to classify it as a warm jupiter, or hot jupiter? or would it still just be a standard jovian planet?


Radius inflation seems to mainly occur in planets with irradiation in the range 105-106 W/m2, see Sestovic et al. (2018). In contrast, at 1 AU from the Sun, the irradiation is 1361 W/m2, which is well below the threshold at which the inflated gas giant radii are observed. It seems unlikely to me that there would be a significant increase in the radius of Jupiter if it were moved to a 1 AU orbit.

As regards the hot/warm Jupiter classification, the term "hot Jupiter" seems to mainly be used to describe the population of giant planets with orbital periods below about 10 days or so. Your Jupiter at 1 AU would not fall into this category.


What is the Temperature of Jupiter?

With an average temperature of minus 234 degrees Fahrenheit (minus 145 degrees Celsius), Jupiter is frigid even in its warmest weather. Unlike Earth, whose temperature varies as one moves closer to or farther from the equator, Jupiter's temperature depends more on height above the surface. This is because heat is driven not by the sun but by the interior of the planet.

Layers of gas

Jupiter is made up predominantly of hydrogen, with some helium. Small traces of other gases also contribute to the planet's composition. These gases fill the entire planet, descending all the way to the core. The surface, as identified by scientists, is the region where the pressure is equal to that at the surface of Earth, one bar. But don't be misled by the term you can't stand on Jupiter's surface, because it isn't solid. Below the surface, the gas becomes liquid and even plasma, all the way to the central core.

Within the regions of gas, the temperature varies in the layers of Jupiter's atmosphere. From the surface to about 30 miles (50 kilometers) up, the temperature decreases as you ascend, ranging from minus 100 C (minus 150 F) to minus 160 C (minus 260 F). In the next layer, the temperature increases with altitude, returning to up to minus 150 F again. At the top of the atmosphere, temperatures can reach as high as 1,340 F (725 C), over 600 miles (1,000 kilometers) above the planet's surface.

Heating sources

Because Jupiter's distance from the sun is an average of 484 million miles (778 million km), heat from the star is weak, though it does contribute. Much of the heating of the gases come from the inside of planet itself. Beneath the surface, convection from the liquid and plasma hydrogen generate more heat than from the sun. This convection keeps the massive gas giant warm enough to avoid it freezing into an icy world.


Astronomers Find Warm Jupiter Orbiting Cool Red Dwarf

A puffy gas giant slightly larger than Jupiter has been discovered orbiting the early M-type dwarf star TOI-1899, thanks to new data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and the Habitable-zone Planet Finder (HPF) on the 10-m Hobby-Eberly Telescope at McDonald Observatory.

An artist’s impression of the warm-Jupiter exoplanet TOI-1899b and the red dwarf TOI-1899, the lowest-mass star known to host a transiting warm Jupiter. Image credit: Sci-News.com.

TOI-1899 is an M0-type star located 419 light-years away in the constellation of Cygnus.

Also known as TIC 172370679 and 2MASS 19574239+4008357, the star has a temperature of 3,652 degrees Celsius and is much cooler than the Sun.

TOI-1899 is about 60% the size and mass of the Sun and is around 7.4 billion years old.

The newfound planet orbits the star once every 29 days at a distance of only 0.16 AU.

Designated TOI-1899b, the alien world is two-thirds the mass of Jupiter but 10% larger in radius.

“Warm Jupiters like TOI-1899b orbit surprisingly close to their star,” said co-author Dr. Rebekah Dawson, an astronomer in the Department of Astronomy and Astrophysics and the Center for Exoplanets and Habitable Worlds at the Pennsylvania State University.

“Even though the planet’s orbital period is long compared to many other giant planets detected and characterized through the transit method, it still places the giant planet much closer to its star than we’d expect from classical formation theories.”

“This is only the fifth Jupiter-sized planet transiting a low-mass star that has been observed and the first with such a long orbital period, which makes this discovery really exciting,” said lead author Caleb Cañas, a Ph.D. student in the Department of Astronomy and Astrophysics and the Center for Exoplanets and Habitable Worlds at the Pennsylvania State University.

TOI-1899b was detected by TESS using the transit method, which searches for stars showing periodic dips in their brightness as a telltale sign of an orbiting object crossing in front of the star and blocking a portion of its light.

The signal was then confirmed as a planet using precision observations from the HPF spectrograph.

“This warm Jupiter is a compelling target for atmospheric characterization with upcoming missions like the James Webb Space Telescope,” said co-author Professor Suvrath Mahadevan, also from the Department of Astronomy and Astrophysics and the Center for Exoplanets and Habitable Worlds at the Pennsylvania State University.

The team’s paper was published in the Astronomical Journal.

Caleb I. Cañas et al. 2020. A Warm Jupiter Transiting an M Dwarf: A TESS Single-transit Event Confirmed with the Habitable-zone Planet Finder. AJ 160, 147 doi: 10.3847/1538-3881/abac67


Astronomers Find Warm Jupiter Orbiting Cool Red Dwarf (Astronomy)

Using a combination of available TESS photometry high-precision, near-infrared spectroscopy with the Habitable-zone Planet Finder and speckle and adaptive optics imaging astronomers confirmed the planetary nature of a warm Jupiter transiting the early M dwarf TOI-1899.

TOI-1899b warm jupiter exoplanet around red dwarf. Credit: Hitendra Prakash

TOI-1899 is an M0-type star located 419 light-years away in the constellation of Cygnus.

Also known as TIC 172370679 and 2MASS 19574239+4008357, the star has a temperature of 3,652 degrees Celsius and is much cooler than the Sun.

TOI-1899 is about 60% the size and mass of the Sun and is around 7.4 billion years old.

The newfound planet orbits the star once every 29 days at a distance of only 0.16 AU.

Designated TOI-1899b, the alien world is two-thirds the mass of Jupiter but 10% larger in radius.

The single-transit, indicated by the dip, of the planet TOI-1899 b passing in front of its host star as detected by NASA’s TESS mission. The single 5-hour event can only reveal the size of planet and a detailed characterization of the transiting object required data from the Habitable-zone Planet Finder Spectrograph, a Penn State led near-infrared spectrograph recently installed on the 10m Hobby-Eberly Telescope at McDonald Observatory in Texas. Credit: Caleb Cañas, Penn State

TOI-1899b was detected by TESS using the transit method, which searches for stars showing periodic dips in their brightness as a telltale sign of an orbiting object crossing in front of the star and blocking a portion of its light.

The signal was then confirmed as a planet using precision observations from the HPF spectrograph.

References: Caleb I. Cañas et al, A Warm Jupiter Transiting an M Dwarf: A TESS Single-transit Event Confirmed with the Habitable-zone Planet Finder, The Astronomical Journal (2020). DOI: 10.3847/1538-3881/abac67


New 'warm Jupiter' exoplanet discovered

The 2 min cadence TESS light curve of TOI-677. Credit: Jordan et al., 2019.

An international team of astronomers reports the discovery of a new "warm Jupiter" alien world transiting a main sequence late F-type star on an eccentric orbit. The newfound exoplanet, designated TOI-677 b, is about 20 percent bigger and more massive than Jupiter. The finding is detailed in a paper published November 13 on arXiv.org.

The so-called "warm Jupiters" are gas giant planets with a minimal mass of 0.3 Jupiter masses and orbital periods ranging between 10 and 100 days. They mark the transition between "hot Jupiters" with an orbital period between one and 10 days and Jupiter analogues with an orbital period longer than 100 days.

TOI-677 b is the newest addition to the list of known "warm Jupiters." The object was first identified as an exoplanet candidate by NASA's Transiting Exoplanet Survey Satellite (TESS) when it observed the star TOI-677 between March 1 and April 22, 2019. Now, a group of astronomers led by Andreas Jordan of Adolfo Ibáñez University in Chile has confirmed the planetary nature of the object transiting TOI-677 by follow-up spectroscopic observations using several ground-based telescopes.

"We followed up TOI-677 with several spectrographs in order to confirm the TESS transiting planet candidate and to measure its mass," the astronomers wrote in the paper.

According to the study, TOI-677 b circles its parent star on an eccentric orbit (with an eccentricity of 0.43) every 11.23 days at a distance of about 0.1 AU from it. The planet has a radius of around 1.17 Jupiter radii and a mass of approximately 1.23 Jupiter masses. Taking into account the TOI-677 b's proximity to its host, the astronomers calculated that the planet has an equilibrium temperature at a level of approximately 1,252 Kelvin.

When it comes to TOI-677, it is a main sequence late F star with solar metallicity and effective temperature of about 6,300 Kelvin. The star has a mass of around 1.18 solar masses and its radius is about 28 percent larger than that of our sun. Observations suggest that the object is nearly 3 billion years old.

Moreover, the astronomers found evidence of a secondary long-term signal in radial velocity measurements, which could mean that the newly detected alien world is not the only object orbiting TOI-677.

"Warm jupiters can be formed via secular gravitational interactions with an outer planet followed by tidal interactions with the star in the high eccentricity stage of the secular cycle. In this context, Dong et al. (2014) predicts that in order to overcome the precession caused by general relativity, the warm jupiters produced via this mechanism should have outer planets at relatively short orbital distances that can be detected with a radial velocity monitoring," the astronomers explained.

However, they added that at the moment it is too early to draw final conclusion about the presence of an outer companion in the TOI-677 system. More studies are needed to determine the exact nature of the long term radial velocity that was reported in the paper.


What are Hot Jupiters?

When astronomers first discovered other planets, they were completely unlike anything we’ve ever found in the Solar System. These first planets were known as “hot jupiters”, because they’re giant planets – even more massive than Jupiter – but they orbit closer to their star than Mercury. Dr. Heather Knutson, a professor at Caltech explains these amazing objects.

“My name is Heather Knutson, and I’m a professor in the planetary science department here at Caltech. I study the properties of extrasolar planets, which are planets that orbit stars other than the sun, so mostly these are our closest exoplanetary neighbors. We’re not talking about planets in other galaxies – we’re mostly talking about planets which are in the same part of our own corner of our galaxy. So these are around some of the closest stars to the sun.”

What is a hot jupiter?

“The planets that I’ve found the most surprising, out of all of the ones I’ve discovered so far, I guess the sort of classic example, is that we’ve see these sorts of giant planets which are very similar to Jupiter, but orbit very much closer in than Mercury is to our sun, so these planets orbit their sun every two or three days and are absolutely getting roasted. We know that they couldn’t have formed there – they had to have formed farther out and migrated in, so what we’re still trying to understand are what are the forces that caused them to migrate in, whereas Jupiter seems to have migrated a little bit but more or less stayed put in our own solar system.”

What do hot jupiters mean for our understanding our own Solar System?

“The implications of these “hot jupiters” as we call them are actually huge for our own solar system, because if you want to know how many potentially habitable earthlike planets are out there, having one of these giant planets just rampage their way though the inner part of the planetary system, and it could toss out your habitable earth and put it into either a much closer orbit or a much further orbit. So knowing how things have moved around will tell you a lot about where you might find interesting planets.”

What is their atmosphere like?

“So, the atmospheres of hot jupiters are very exotic, by solar system standards. They typically have temperatures of a thousand to several thousand Kelvin, so at these temperatures these planets could have clouds of molten rock, for example. They have atmospheric compositions that would seem very exotic to us – they’re actually more similar to the compositions of relatively cool stars, so we have to adapt to describe these planets – we actually use stellar models to describe their atmospheres. We think that they’re also probably also tidally locked, which is very interesting because it means that one side of the planet is getting all of the heat and the other side is sort of in permanent night. And one thing we do is to try and understand the effect that has on the weather patterns on these planets, so you have winds that are pretty good at carrying that around the night side and mixing everything up, or do these planets have these just extreme temperature gradients between the day side and the night side.”

Hot Jupiter planet. Image Credit: ESA
How’d they get there?

“So, we have a couple of theories for how hot jupiters may have ended up in their present day orbits. One theory is, that after they formed, that they were still embedded in the gas disc where they formed, and maybe they interacted with the disc as such that it kind of torqued and pulled them and so that’s kind of an early migration theory. There’s also a late migration theory version where when after the disc had gone away, these planets had interacted with a third body in the system, so maybe you had another distant massive planet or maybe you had a planet that was part of a binary star system, and those three body interactions excited a large orbital eccentricity in the innermost planet, and once it starts coming in closer to the star, the tides start to damp out the eccentricities, so what you end up with is something which is a gas giant planet in a very short period circular orbit.

So that’s kind of a more complicated story, but there are some clues in the data that might be true for at least a subset of the hot jupiters that we study.”


Astronomy Chapter 8: Jovian Planet Systems

-Hydrogen compounds are more abundant than rock/metal so jovian planets got bigger and acquired H/He atmospheres.

-The jovian cores are very similar:

-Greater compression is why Jupiter is not much larger than Saturn in size, even though it is three times more massive.

-Layers under high pressure and temperatures

10 Earth masses) made of hydrogen compounds, metals, and rock

-Hydrogen acts like a metal at great depths because its electrons move freely.

-The core is thought to be made of rock, metals, and hydrogen compounds

-Gases escaping Io feed the donut-shaped Io torus around Jupiter (

-Different cloud layers correspond to freezing points of different hydrogen compounds.

• Medium-sized moons (300-1500 km)
- Geological activity in past

-Have substantial amounts of ice

-Formed in orbit around jovian planets

-Clear evidence of geological activity

-No tidal heating, no orbital resonances

-It is the only moon in the solar system that has a thick atmosphere.

-Only large rocky planets have enough heat for activity.

-Ice melts at lower temperatures.

-They orbit over Saturn's equator.

HOW WE KNOW:
-Rings aren't leftover from planet formation because the particles are too small to have survived this long.


TESS Discovers New Warm Jupiter

An artist’s impression of the warm Jupiter TOI-677b and its host star. Image credit: Sci-News.com.

“Warm giants, loosely defined as systems with periods over 10 days, are close enough to the star that they are likely to have undergone significant migration, but not as close that tidal effects can erase the potential imprints of that migration,” said Dr. Andres Jordan of the Universidad Adolfo Ibanez and Millennium Institute for Astrophysics and his colleagues.

“In the same vein, they are far enough from their parent star that their radii have not been inflated by the mechanism that acts to bloat the radii of hotter giants.”

“But while it is clear that these systems are very interesting, the population of known warm giants around nearby stars (allowing the most detailed characterization) is still very small.”

Designated TOI-677b, the new warm giant was detected by NASA’s Transiting Exoplanet Survey Satellite (TESS).

“We followed up the host star, TOI-677, with several spectrographs in order to confirm the TESS transiting planet candidate and to measure its mass,” the astronomers explained.

They found that TOI-677b is approximately 1.2 times larger and more massive than Jupiter.

“Its radius is in line with what is expected for a gas giant with a core of 10 Earth masses according to the standard models,” they said.

The F-type star TOI-677 (bright star in the center). Image credit: Centre de Données astronomiques de Strasbourg / SIMBAD / DECam Plane Survey.

TOI-677 is an F-type star that is approximately 464 light-years away from Earth.

Also known as HD 297549 and 2MASS J09362869-5027478, this star is slightly bigger and more massive than the Sun, and is about 2.92 billion years old.

TOI-677b orbits the star with an orbital period of 11.24 days on an eccentric orbit.

“With an eccentricity of 0.435, it lies in the upper range of eccentricity values for planets with similar periods in the currently known sample,” Dr. Jordan and co-authors said.

A paper detailing the discovery will be published in a journal of the American Astronomical Society.

Andrés Jordán et al. 2019. TOI-677 b: A Warm Jupiter (P=11.2d) on an eccentric orbit transiting a late F-type star. arXiv: 1911.05574


What is the Surface of Jupiter Like?

Have you ever wondered what it might feel like to stand on Jupiter’s surface? Well, there’s a problem. Jupiter is made up almost entirely of hydrogen and helium, with some other trace gases. There is no firm surface on Jupiter, so if you tried to stand on the planet, you sink down and be crushed by the intense pressure inside the planet.

When we look at Jupiter, we’re actually seeing the outermost layer of its clouds. Jupiter upper atmosphere is made of up to 90% hydrogen, with 10% helium, and then other gases like ammonia. The bands and storms that we can see on the planet are all generated in the upper atmosphere. The cloud layer we can see is made of ammonia, and only extends down for about 50 km or so. The large storms like the Great Red Spot occur within this layer although it’s thought they may dredge up material from deeper down inside the planet.

If you could stand on the surface of Jupiter, you would experience intense gravity. The gravity at Jupiter’s surface is 2.5 times the gravity on Earth. If you weighed 100 pounds on Jupiter, you’d weigh 250 pounds on Jupiter. Of course, there’s no actual surface, so you’d just sink into the planet if you tried to stand on it.

We’ve written many articles about Jupiter for Universe Today. Here’s an article about how Jupiter might have captured a comet as a temporary moon, and does Jupiter have a solid core?

We’ve also recorded an entire episode of Astronomy Cast all about Jupiter. Listen here, Episode 56: Jupiter.


Temperature Anomalies and Variations:

Whereas Neptune averages the coldest temperatures in the Solar System, a strange anomaly is the planet’s south pole. Here, it is 10 degrees K warmer than the rest of planet. This “hot spot” occurs because Neptune’s south pole is currently exposed to the Sun. As Neptune continues its journey around the Sun, the position of the poles will reverse. Then the northern pole will become the warmer one, and the south pole will cool down.

Neptune’s more varied weather when compared to Uranus is due in part to its higher internal heating, which is particularly perplexing for scientists. Despite the fact that Neptune is located over 50% further from the Sun than Uranus, and receives only 40% its amount of sunlight, the two planets’ surface temperatures are roughly equal.

Four images of Neptune taken a few hours apart by the Hubble Space Telescope on June 25-26, 2011. Credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

Deeper inside the layers of gas, the temperature rises steadily. This is consistent with Uranus, but oddly enough, the discrepancy is larger. Uranus only radiates 1.1 times as much energy as it receives from the Sun, whereas Neptune radiates about 2.61 times as much. Neptune is the farthest planet from the Sun, yet its internal energy is sufficient to drive the fastest planetary winds seen in the Solar System. The mechanism for this remains unknown.

And while temperatures on Pluto have been recorded as reaching lower – down to 33 K (-240 °C -400 °F) – Pluto’s status as a dwarf planet mean that it is no longer in the same class as the others. As such, Neptune remains the coldest planet of the eight.

We have recorded an entire episode of Astronomy Cast just about Neptune. You can listen to it here, Episode 63: Neptune.