Rogue planets could make the stars bigger


Unveiling of Evil Planets with NASA's Roman Space Telescope

High resolution illustration of the Roman spaceship against a starry sky background. Credit: NASA’s Goddard Space Flight Center

An upcoming NASA mission could find that there are more vicious planets – planets that float in space without orbiting a sun – then there are stars in the Milky Way, a new theorized study.


“This gives us a window into these worlds we would not otherwise have,” said Samson Johnson, an astronomy student at Ohio State University and lead author of the study. “Imagine our little rocky planet just floating freely in space – that’s what this mission will help us find.”

The study was published today in he Astronomical Journal.

The study calculated that NASA’s upcoming Nancy Grace Roman Space Telescope could find hundreds of orbiting planets in the Milky Way. Identifying Johnson, Johnson said, will help scientists close the total number of evil planets in our galaxy. Rogue, as free-floating, planets are isolated objects that have masses similar to those of planets. The origin of such objects is unknown, but one possibility is that they were previously associated with a host star.

“The universe could shake with rough planets and we would not even know it,” said Scott Gaudi, a professor of astronomy and distinguished university scientist at Ohio State and a co-author of the paper. “We would never discover it without undertaking an in-depth, space-based microlensing study like Roman will do.”

The Roman telescope, named after NASA’s first chief astronomer, who was also called ‘the mother’ of the Hubble Space Telescope, will try to build the first census of evil planets, which, Johnson said. , scientists could help understand how those planets form. Novel will also have other objectives, including searching for planets orbiting stars in our galaxy.

That process is not well understood, although astronomers know it is messy. Rogue planets could form in the gaseous disks around young stars, similar to those planets still bound to their host stars. After formation, they could later be delayed through interactions with other planets in the system, or even fly through events by other stars.

This animation shows how gravity microlensing can reveal island worlds. As an unseen rough planet passes for a distant star from our vantage point, the star’s light bends as it orbits the planet through the warped space-time. The planet acts as a cosmic magnifying glass, enhancing the brightness of the background star. Credit: NASA’s Goddard Space Flight Center / CI Lab

Or they could form as dust and gas swirl together, similar to the way stars form.

The Roman telescope, Johnson said, is designed not only to locate free-floating planets in the Milky Way, but to test theories and models that predict how these planets form.

Johnson’s study found that this mission is probably 10 times more sensitive to these objects than existing efforts, which are primarily based on ground-level telescopes. It will concentrate on planets in the Milky Way, between our sun and the center of our galaxy, which are about 24,000 light-years away.

“Several vicious planets have been discovered, but to get a complete picture, our best bet is something like Roman,” he said. “This is a whole new frontier.”

Rogue planets have historically been difficult to detect. Astronomers discovered planets outside the Earth’s solar system in the 1990s. These planets, called ecopoplanets, range from very hot gas balls to rocky, dusty worlds. Many of them around their own stars, the way Earth orbits the sun.

But it is likely that some of them do not. And although astronomers have theories about how rogue planets form, no mission has studied those worlds in the detail that Roman wants.

The mission, which is scheduled to launch in the next five years, will search for vicious planets using a technique called gravitational microlensing. That technique requires the gravitational pull of stars and planets to bind the light and magnify stars that pass behind them from the point of view of the telescope.

This illustration shows a rough planet drifting through the galaxy alone. Credit: NASA / JPL-Caltech / R. Hurt (Caltech-IPAC)

This microlensing effect is linked to Albert Einstein’s Theory of General Relativity and allows a telescope to find planets thousands of light-years away from Earth – far beyond other planetary detection techniques.

But because microlensing only works when the gravitational force of one planet or star bends and magnifies the light of another star, the effect of each given planet or star is visible only once in a few million years for a short time. And because orbiting planets sit in space on their own, without a star nearby, the telescope must be highly sensitive to detect that magnification.

The study published today estimates that this mission can identify planetary planets that are as large as the masses of Mars. Mars is the second-smallest planet in our solar system and is just slightly larger than half the Earth.

Johnson said these planets are unlikely to support life. “They would probably be extremely cold because they have no star,” he said. (Other research missions in which Ohio State state economists will search for exoplanets that can host life.)

But studying them will help scientists understand more about how all planets form, he said.

“If we find many low-mass planets, we will know that if stars form planets, they are likely to emit many other objects in the galaxy,” he said. “This helps us to get a grip on the formation path of planets in general.”


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More information:
Samson A. Johnson et al. Predictions from the Nancy Grace Roman Space Telescope’s Galactic Exoplanet Survey. II. Free floating rates for asteroids, The Astronomical Journal (2020). DOI: 10.3847 / 1538-3881 / aba75b, iopscience.iop.org/article/10. … 847 / 1538-3881 / aba75b

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Citation: Rogue Planets Could Grow the Stars (2020 August 21) Retrieved August 21, 2020 from https://phys.org/news/2020-08-rogue-planets-outnumber-stars.html

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