Venus-like worlds are surprisingly common in 'habitable' zones

[Admin]

The current definition of habitable zone only examines the amount of sunlight reaching a planet. It may be time to question that definition.

Venus-like worlds are surprisingly common in 'habitable' zones : Read more

 

[rod]

An interesting report on the model. The cited paper, [2204.10919] The Outer Edge of the Venus Zone Around Main-Sequence Stars (arxiv.org) "Our results show that the outer edge of the Venus zone resides at 3.01, 1.36, 0.68, 0.23, and 0.1 AU, respectively."

Presently this site shows 5031 exoplanets now, The Extrasolar Planets Encyclopaedia (exoplanet.eu)

2343 show radii 3 or less earth size. Their semi-major axis fall within 0.0034 au to 1.98 au.

The NASA site NASA Exoplanet Archive (caltech.edu) , now shows 5021 exoplanets. 2667 have radii 3 or less earth size. Their semi-major axis fall within 0.0058 au to 1.1218 au. In the paper cited, I did not see any specific exoplanets used from these two sites as examples supporting the model. So far, it does not seem that any earthlike exoplanet has been clearly identified, let alone with life flourishing on it.

 

[rod]

I read this report yesterday on protoplanetary discs and their mass sizes. Planet-forming disks evolve in surprisingly similar ways, https://phys.org/news/2022-05-planet-forming-disks-evolve-surprisingly-similar.html

My observation. Timely in view of the space.com report on Venus and HZ areas.

Reference paper, Survey of Orion Disks with ALMA (SODA), https://www.aanda.org/articles/aa/full_html/2022/05/aa41913-21/aa41913-21.html, 06-May-2022.

My observation. While some of the reported discs could contain 100 earth masses of dust or more, many show <= 2.2 earth masses. Using 1 solar mass star and applying the MMSN, the initial dust mass ~ 3.329428E+01 or 33.29 earth masses where 1E-4 Mstar for canonical model values for dust. Apparently most of the 870 discs (873 in the paper) studied are small compared to the MMSN values used for the solar nebula and primordial disc spinning around the Sun. The paper states, "Figure 1 shows the locations of all disks with masses (assuming optically thin emission) higher than 100 M⊕ in dust in Orion A. We find 20 such objects, larger than any other such sample, and the first complete sample of massive protoplanetary disks located within the same star-forming region. The most massive object is [MGM2012]-540, with Mdust = 364 ± 0.5 M⊕. In L1641, Grant et al. (2021) previously identified only 6 disks with masses more than 100 M⊕; this survey increases that number to 16 in the same part of the cloud, emphasizing the importance of an unbiased survey for characterizing the upper end of the disk mass distribution."

My note, today we have about 447 earth masses in the ecliptic from Mercury to Pluto. Apparently none of the 873 discs studied can be definitely shown forming new planets or solar systems like ours. This report provided me with some stats for 873 disc studied in Orion A cloud. Most look small mass sizes with 2.2 earth mass dust. Using gas content, those could be up to 220 earth masses total (dust + gas). Explaining how Venus formed and Earth formed with such an abundance of life, remains challenging and difficult.