This week in astronomy news: A mini-satellite demonstrates exoplanet-hunting technology, a superconducting camera tests its abilities to image exoplanets, and bad news for life on Proxima Centauri b.

Astrophysics CubeSat Demos Exoplanet-Hunting Tech

NASA announced that the Arcsecond Space Telescope Enabling Research in Astrophysics (ASTERIA) has accomplished its mission objectives, including steady pointing and temperature control, that will allow future mini-satellites to search for exoplanets.

ASTERIA deployment
ASTERIA was deployed from the International Space Station in November 2017.

Launched for the International Space Station in August 2017, ASTERIA was deployed into low-Earth orbit last November and will continue operating through May. The “small but mighty” CubeSat is slightly larger and ten times heavier than a box of cereal: 10 cm × 20 cm × 30 cm and 10 kg — tiny compared to the 4.7 m × 2.7 m, 478-kg Kepler telescope.

Using mostly off-the-shelf hardware, ASTERIA has shown the ability to steadily point at a bright star, wobbling only 0.5 arcseconds over 20 minutes. This pointing stability is crucial for monitoring the brightness of stars, enabling researchers to search for the subtle dips that would indicate an orbiting exoplanet. The control system also minimized thermal noise by maintaining temperature fluctuations less than 0.01°C.

Read more about the mission in NASA’s press release.

Superconducting Camera Developed to Image Exoplanets

Benjamin Mazin (University of California Santa Barbara) has led a team in developing Darkness, a superconducting camera that enables unprecedented views of exoplanets orbiting their stars — a challenge often likened to photographing a firefly hovering near a floodlight. Exoplanets have to date only been directly imaged when they’re far from their star and at very young ages, when they still radiate heat leftover from their formation.

Darkness can take thousands of frames per second with no read noise or dark current, which allows the camera to image a planet 100 million times fainter than its star. This makes accessible even those exoplanets that no longer emit their own radiation but only reflect light from their host star.

The detector also acts as an integral field spectrograph, which means it can identify the location, wavelength, and arrival time of every incoming photon. The timing information can help distinguish exoplanet photons from the speckles associated with scattered or refracted light.

Darkness is designed for the 200-inch Hale telescope at Palomar Observatory, where it’s aided by an adaptive optics system and a coronagraph that blocks the host star’s light. Read more about the instrument and future plans in the press release from the University of California Santa Barbara.

First Naked-Eye Flare Detected from Proxima Centauri

flaring M dwarf
Young M dwarf stars can unleash dangerous flares, spelling doom for closely orbiting planets. This illustration depicts a superflare on one of the stars in the binary DG Canum Venaticorum, which is about 30 million years old.
NASA Goddard Space Flight Center / S. Wiessinger

We already know that the nearest star to Earth isn't the kindest host to its potentially Earth-mass exoplanet: Proxima Centauri is a red dwarf whose X-ray and ultraviolet flares would likely already have turned Proxima Centauri b into a desert world. Many of these flares are small but sufficiently frequent to do damage to any potential protective ozone layer.

But some flares are quite powerful. In March 2016 the all-sky monitoring Evryscope detected the star's first naked-eye flare, ten times more powerful than any other recorded. Combining this data with 23 other powerful flares that Evryscope has detected from the star, Ward Howard (University of North Carolina at Chapel Hill) and colleagues conclude that if the planet were somehow able to build an ozone layer, it would lose it in a few hundred thousand years.

Read more in the study as published on the astrophysics preprint arXiv.


You must be logged in to post a comment.