Ross 128 - ~Earth-mass planet at inner edge of HZ

HARPS has done it again.

Closest Temperate World Orbiting Quiet Star Discovered
https://www.eso.org/public/news/eso1736/

~1.4 Earth-masses. ~1.3 x Earth's insolation.

GREAT !
A new target for ALMA, JWST, ect...

https://www.eso.org/public/archives/releases/sciencepapers/eso1736/eso1736a.pdf

A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs

JWST is probably not going to be so useful for this one. From the paper:

Quote :

Transit spectroscopy being excluded, we turn to the potential of measuring phase curves. Snellen et al. (2017) estimated that five days of JWST observations could detect the putative atmosphere of Proxima Cen b (see also Kreidberg & Loeb 2016). Ross 128 b is not as favorable however, since its host star is 1.4 times larger and, at near- or mid-infrared wavelengths, 3 − 4 times fainter than Proxima Centauri. Similar JWST observations for Ross 128 b are thus likely to be prohibitively expensive.

E-ELT appears to be the way forward here.

Andrew LePage has done a Habitable Planet Reality Check article for Ross 128 b on Drew Ex Machina.

It's still an UV Ceti flaring star :p

Stellar and Planetary Characterization of the Ross 128 Exoplanetary System from APOGEE Spectra
https://arxiv.org/abs/1805.11633

Quote :

The first detailed chemical abundance analysis of the M dwarf (M4.0) exoplanet-hosting star Ross 128 is presented here, based upon near-infrared (1.5--1.7 \micron) high-resolution (R∼22,500) spectra from the SDSS-APOGEE survey. We determined precise atmospheric parameters Teff=3231±100K, logg=4.96±0.11 dex and chemical abundances of eight elements (C, O, Mg, Al, K, Ca, Ti, and Fe), finding Ross 128 to have near solar metallicity ([Fe/H] = +0.03±0.09 dex). The derived results were obtained via spectral synthesis (1-D LTE) adopting both MARCS and PHOENIX model atmospheres; stellar parameters and chemical abundances derived from the different adopted models do not show significant offsets. Mass-radius modeling of Ross 128b indicate that it lies below the pure rock composition curve, suggesting that it contains a mixture of rock and iron, with the relative amounts of each set by the ratio of Fe/Mg. If Ross 128b formed with a sub-solar Si/Mg ratio, and assuming the planet's composition matches that of the host-star, it likely has a larger core size relative to the Earth. The derived planetary parameters -- insolation flux (SEarth=1.79±0.26) and equilibrium temperature (Teq=294±10K) -- support previous findings that Ross 128b is a temperate exoplanet in the inner edge of the habitable zone.

Estimate of the insolation has gone up a bit, though still consistent with the earlier value. I guess habitability relies on building up a large amount of clouds on the dayside, or that it is a desert planet (which always struck me as cheating, being able to support liquid water by virtue of not having water doesn't seem particularly useful).