Astronomers are Starting to Find Planets in Much Longer Orbits. Cooler, More Habitable Planets

We’re getting better and better at detecting exoplanets. Using the transit method of detection, the Kepler Space Telescope examined over 530,000 stars and discovered over 2,600 explanets in nine years. TESS, the successor to Kepler, is still active, and has so far identified over 1800 candidate exoplanets, with 46 confirmed.

But what if, hidden in all that data, there were even more planets? Astronomers at Warwick University said they’ve found one of these “lost” planets, and that they think they’ll find even more.

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A Star Has Been Found That Pulsates, But Only on One Side

In the 17th century, astronomers witnessed many stellar events that proved that the starry sky was not “fixed and eternal.” This included stars whose brightness varied over time – aka. “variable stars.” By the 20th century, many variable stars had been cataloged and astronomers have discerned subclasses of them as well – notably, stars that swell and shrink, known as pulsating variables.

In all cases, these variable stars were found to have rhythmic pulsations that were visible from all sides. But a recent discovery by an international team has confirmed that there are variable stars that can pulse from only one side. This pulsating star, part of a system known as HD 74423, is located about 1,500 light-years from Earth and is the first of its kind to be found.

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NASA’s TESS Watched an Outburst from Comet 46P/Wirtanen

TESS, the Transiting Exoplanet Survey Satellite, has imaged an outburst from the comet 46P/Wirtanen. It caught the outburst in what NASA is calling the clearest images yet of a comet outburst from start to finish. A comet outburst is a significant but temporary increase in the comet’s activity, outside of the normal sunlight-driven vaporization of ices that creates a comet’s coma and tail.

Astronomers aren’t certain what causes them, but a new study based on this observation is shedding some light on them.

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TESS Just Found its First Earth-Sized World

Artist's conception of HD 21749c, the first Earth-sized planet found by NASA's Transiting Exoplanets Survey Satellite (TESS), as well as its sibling, HD 21749b, a warm sub-Neptune-sized world. Credit: Robin Dienel/Carnegie Institution for Science.

NASA’s new planet-hunting telescope, TESS (Transiting Exoplanet Survey Satellite), just found its first Earth-sized world. Though the Earth-sized planet, and its hot sub-Neptune companion, were first observed by TESS in January 2019, it’s taken until now to confirm their status with ground-based follow-up observations. The discovery is published in The Astrophysical Journal Letters.

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TESS Finds its Third Planet, a sub-Neptune with a 36-Day Orbit

An artist's illustration of the newly-discovered exoplanet HD21749b. Image Credit: By NASA/MIT/TESS - https://static01.nyt.com/images/2019/01/08/climate/08TESS2/merlin_148878360_2fd4c6fe-ad22-400b-a882-f6b3a698a573-superJumbo.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=75686540

After only three months of operation, NASA’s TESS (Transiting Exoplanet Survey Satellite) spacecraft is delivering on its mission to find more exoplanets. A new paper presents the latest finding: a sub-Neptune planet with a 36-day orbit around its star. This is the third confirmed exoplanet that TESS has found.

The planet orbits a K-dwarf star about 52 light years away, in the constellation Reticulum. In astronomical terms, this makes the planet pretty close to us, and a great candidate for follow-up observations. Even better, it may have a sibling planet about the same size as Earth.

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Now that TESS is Operational, Astronomers Estimate it’ll Find 14,000 Planets. 10 Could Be Earthlike Worlds in a Sunlike Star’s Habitable Zone

An artist’s illustration of the Transiting Exoplanet Survey Satellite. Credits: NASA Goddard Space Flight Center

How many exoplanets are there? Not that long ago, we didn’t know if there were any. Then we detected a few around pulsars. Then the Kepler spacecraft was launched and it discovered a couple thousand more. Now NASA’s TESS (Transiting Exoplanet Survey Satellite) is operational, and a new study predicts its findings.

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The Power of the Wobble: Finding Exoplanets in the Shifting of Starlight

They say there’s more than one way to skin an interstellar cat, and in astronomy there’s more than one way to find alien exoplanets orbiting a distant star. With the recent shut-down of NASA’s prolific Kepler mission and its windfall of discoveries, it’s time to look towards the future, and towards alternatives.

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TESS Practices on a Comet Before Starting on its Science Operations

An artist’s illustration of the Transiting Exoplanet Survey Satellite. Credits: NASA Goddard Space Flight Center

On April 18th, 2018, NASA deployed the Transiting Exoplanet Survey Satellite (TESS), a next-generation exoplanet hunting telescope that is expected to find thousands of planets in the coming years. Alongside other next-generation telescopes like the James Webb Space Telescope (JWST), TESS will effectively pick up where space telescopes like Hubble and Kepler left off.

The mission recently started science operations (on July 25th, 2018) and is expected to transmit its first collection of data back to Earth this month. But before that, the planet-hunting telescope took a series of images that featured a recently-discovered comet known as C/2018 N1. These images helped demonstrate the satellite’s ability to collect images over a broad region of the sky – which will be critical when it comes to finding exoplanets.

As the name would suggest, the TESS mission is designed to search for planets around distant stars using the Transit Method (aka. Transit Photometry). For this method, distant stars are monitored for periodic dips in brightness, which are indications that a planet is passing in front of the star (aka. transiting) relative to the observer. From these dips, astronomers are able to estimate a planet’s size and orbital period.

This method remains the most effective and popular means for finding exoplanets, accounting for 2,951 of the 3,774 confirmed discoveries made to date. To test its instruments before it began science operations, TESS took images of C/2018 N1 over a short period near the end of the mission’s commissioning phase – which occurred over the course of 17 hours on July 25th.

The comet that it managed to capture, C/2018 N1, was discovered by NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) satellite on June 29th. This comet is located about 48 million km (29 million mi) from Earth in the southern constellation Piscis Austrinus. In these pictures, which were compiled into a video (shown below), the comet is seen as a bright dot against a background of stars and other objects.

As it moves across the frame (from right to left), the comet’s tail can be seen extending to the top of the frame, and gradually changes direction as the comet glides across the field of view. The images also reveal a considerable amount of astronomical activity in the background. For instance, image processing causes the stars to shift between white and black, which highlights some variable stars visible in the images.

These are stars that change brightness as a result of pulsation, rapid rotation, or being eclipsed by a binary neighbor. A number of Solar System asteroids are also visible as small white dots moving across the field of view. Last, but not least, some stray light that was reflected from Mars is also visible near the end of the video. This light appears as a faint broad arc that moves across the middle section of the frame, from left to right.

This effect was due to the fact that Mars was at its brightest at the time since it was near opposition (i.e. at the closest point in its orbit to Earth). These images showcase the capabilities of the TESS mission, even though they only show a fraction of the instrument’s active field of view.

In the coming weeks and months, TESS science team will continue to fine-tune the spacecraft’s performance as it searches for extra-solar planets. As noted, it is expected that TESS will find thousands of planets in our galaxy, vastly increasing our knowledge of exoplanets and the kinds of worlds that exist beyond our Solar System!

And be sure to check out the video of the images TESS captured, courtesy of NASA’s Goddard Space Flight Center:

Further Reading: NASA