Unique Teardrop Star Discovered by NASA Satellite

Gabriel Pérez Díaz (IAC)
Gabriel Pérez Díaz (IAC)

NASA built its Transiting Exoplanet Survey Satellite, or TESS, to search for worlds outside our solar system, but it can also detect bodies that are much bigger than the average planet. Its latest discovery—a teardrop-shaped, pulsating star dubbed HD74423—has roughly 1.7 times the mass of the sun, and it's the first star of its kind studied by scientists, CBS News reports.

An international team of astronomers published their findings about the star captured by TESS in the journal Nature Astronomy [PDF]. HD74423 is remarkable in many ways. Located 1500 light-years from Earth in the Milky Way galaxy, it shares a binary system with a red dwarf. The large star is tidally locked with the smaller one, meaning one side of HD74423 is always being pulled by its partner's gravitational pull in a tight orbit. This has resulted in its warped teardrop shape.

The fact that it's tidally locked also gives the star its unique pulsation pattern. Many stars like our own sun pulsate, which means they rhythmically become brighter and dimmer. When this phenomenon has been observed in the past, the starlight always fluctuates on all sides. Because it's distorted by its neighbor, HD74423 pulsates on only one side—a celestial anomaly. Even the star's composition is noteworthy. Study co-author Simon Murphy of Australia's Sydney Institute for Astronomy said that he first noticed the star because it was poor in metals, something that set it apart from other hot stars like it.

"We've known theoretically that stars like this should exist since the 1980s," study co-author Don Kurtz of Britain's University of Central Lancashire said in a press release. "I've been looking for a star like this for nearly 40 years and now we have finally found one."

HD74423 is just the latest groundbreaking discovery made by NASA's Transiting Exoplanet Survey Satellite. Earlier in 2020, TESS located a potentially habitable, Earth-sized planet 100 light-years away.

[h/t CBS News]

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Uranus Reaches Opposition on Halloween in 2020

Christine Schmitt, Flickr // CC BY-NC-ND 2.0
Christine Schmitt, Flickr // CC BY-NC-ND 2.0

Uranus is roughly 1.75 billion miles away from Earth, which makes it difficult to spot without a telescope most nights. But on Saturday, October 31, the seventh planet from the sun will be worth looking for. Uranus reaches opposition that night, making it appear extra bright in the night sky.

What Is Uranus at Opposition?

An opposition occurs when the Earth falls perfectly between another planet and the sun. When this happens, the sun's light appears to fully illuminate the planet's surface, boosting its brightness level to the maximum.

Uranus reaches opposition on October 31 in 2020. During this event, Uranus will hit a limiting magnitude of 5.86, which is about the minimum brightness for what's visible with the naked eye.

How to Look for Uranus at Opposition

Spotting Uranus at opposition will be slightly more difficult in 2020 than in years past. The phenomenon coincides with a full moon that will make dimmer stars and planets—including Uranus—harder to see in the night sky. The planet sits in the constellation Aries, which regrettably appears close to the moon for most of the night.

Uranus should appear as a small, blue-green disc when using a telescope. Even if you have trouble spotting the seventh planet, it will still be worth checking out the night sky on October 31: Halloween this year coincides with a rare blue moon.