Articles in 2021

A sensitive Breakthrough Listen search for technosignatures towards Proxima Centauri has resulted in a viable narrowband signal. The observational approach, using the Parkes Murriyang telescope, is described here, while the signal of interest is analysed in a companion paper by Sheikh et al.

A radio signal detected in the direction of Proxima Centauri in a Breakthrough Listen programme is analysed for signs that it was transmitted by extraterrestrial intelligent life, using a newly developed framework. However, the signal ‘blc1’ is likely to be terrestrial radio-frequency interference.

A brightness dip in the extragalactic X-ray binary M51-ULS-1 can be well fit by a planet transit model in which the eclipser is most likely Saturn-sized. The locations of possible orbits are consistent with the survival of a planet bound to a mass-transfer binary.

Lucy mission’s bold objective is to study a class of distant asteroids — the Trojan asteroids — never explored before by spacecraft, explain Deputy Project Scientist Simone Marchi and Deputy Principal Investigator Cathy Olkin.

A population study of near-infrared spectra of 19 hot giant planets shows a correlation between the strength of the 1.4 μm water band and temperature, which is broadly regulated by irradiation. However, the observed scatter around the mean is indicative of the effect of individual planetary formation pathways on the composition.

Radio images from the Low Frequency Array have revealed complex, filamentary radio emission around a radio galaxy undergoing multiple episodes of radio outbursts, showcasing the importance of magnetic fields for the survival of radio filaments far from the radio core.

From its optical light curve, the white dwarf in the binary system TW Pictoris appears to be switching between two different intensities of accretion on timescales of hours. This behaviour is reminiscent of that seen in transitional millisecond pulsars, where the switching occurs several times a minute.

Globular cluster NGC 2005 in the Large Magellanic Cloud (LMC) bears the elemental hallmarks of being an accreted object: a surviving fragment of a galaxy that fell into the LMC long enough ago to have erased any dynamical signature of accretion.

LOFAR observations of a galaxy group reveal multiple generations of cosmic-ray bubbles. The bubble buoyancy power offsets the radiative cooling of the intragroup medium, while magnetic fields prevent mixing between the bubbles and the external medium.

While pulsar timing observations are currently unable to distinguish a binary black hole astrophysical foreground from a cosmological background, integrated bounds on the ultra-low-frequency gravitational wave spectrum from other cosmological probes may help to break this degeneracy.

The authors present 19 detections of coherent low-frequency radio emission from M dwarfs using the Low Frequency Array. The sample includes both chromospherically active and quiescent stars, but radio luminosities are independent of coronal and chromospheric activity indicators.

Cosmological simulation TNG50 reveals that a recently discovered population of isolated but non-star-forming ultra-diffuse galaxies may have been gas-rich satellites of much more massive galaxies in the distant past.

Without a proper accounting of known and unknown systematics and uncertainties, combining information across multiple surveys, wavelengths, and detectors may be risky. Realizing the true potential of multi-messenger and panchromatic astrophysics requires getting data integration right.

Held in Suzhou, Jiangsu province of China in June 2021, the conference served to unite a wide community of planetary science within China, and hopes to become one of the world’s premier planetary science conferences in the future.