2021, November 22:  Nearly 5,000 Exoplanets

November 22, 2021:  NASA Says, “Scientists have added a whopping 301 newly confirmed exoplanets to the total exoplanet tally.”

Over 4,500 planets have been found around other stars, but scientists expect that our galaxy contains millions of planets. There are multiple methods for detecting these small, faint bodies around much larger, bright stars. Credit: NASA/JPL-Caltech
Image Caption – Over 4,500 planets have been found around other stars, but scientists expect that our galaxy contains millions of planets. There are multiple methods for detecting these small, faint bodies around much larger, bright stars. Credit: NASA/JPL-Caltech

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by Jeffrey L. Hunt

Over 300 newly validated exoplanets have been added to the tally of 4,569 known planets in other star systems.

ExoMiner, a computer system that studies data from scientific data, has moved through raw numbers to uncover this latest batch of finds.  The system learns from its mistakes and refines how it finds actual exoplanets.  The system supports data surveys by expert observers and even citizen scientists.

The system takes data from the Kepler spacecraft that looks at the stars in its field of view.  Possibly seeing a thousand stars at a time, ExoMiner pores through the data looking for the tell-tale signs of possible exoplanets.

When a planet crosses directly between us and its star, we see the star dim slightly because the planet is blocking out a portion of the light. This is one method scientists use to find exoplanets. They make a plot called a light curve with the brightness of the star versus time. Using this plot, scientists can see what percentage of the star's light the planet blocks and how long it takes the planet to cross the disk of the star. Credit: NASA's Goddard Space Flight Center
Image Caption – When a planet crosses directly between us and its star, we see the star dim slightly because the planet is blocking out a portion of the light. This is one method scientists use to find exoplanets. They make a plot called a light curve with the brightness of the star versus time. Using this plot, scientists can see what percentage of the star’s light the planet blocks and how long it takes the planet to cross the disk of the star. Credit: NASA’s Goddard Space Flight Center

The general plan to find exoplanets is to monitor the light from the stars.  If a planet is revolving around the star, it passes between the star and the satellite.  The planet blocks a small portion of starlight that the satellite can detect.  A light curve is plotted to show the dip in the star’s brightness.  If the dip repeats in a predictable pattern, then an exoplanet might be the culprit causing the change of brightness.

The potential exoplanet’s distance from the star, its mass and size can be estimated from the depth of the light curve and the speed of repetition.

Once a candidate exoplanet is found, other techniques, such as the wobble in the main star’s motion and direct photographs are two of the method that help confirm the presence of the planet around the star.

It is estimated that on average, there is at least one planet for every star in the Milky Way galaxy.

The scoreboard for locating more planets is likely to increase.  ExoMiner is one way to help look for new planets in the celestial haystack.

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