Exoplanets may be hiding behind the 'Neptunian ridge

[Admin]

Astronomers have discovered a hidden feature in exoplanet distribution that could explain the absence of so-called "hot-Neptunes" close to their stars.

Exoplanets may be hiding behind the 'Neptunian ridge : Read more

 

[rod]

"To understand how the Neptunian desert and savanna evolved, Bourrier and colleagues used data from NASA's Kepler space telescope. Defining precise regions of the "Neptunian landscape," they found a distinct region between the desert and the savanna, representing an orbital period of 3.2 to 5.7 Earth days. They dubbed this the "Neptunian ridge," finding that it reveals some of the intricate processes of Neptunian planet migration."

This is interesting orbital period area using the exoplanet sites. https://exoplanet.eu/home/

At the exoplanet.eu site I found 947 listed in this orbit period range. Masses run 0.2606 earth up to 60.86 Jupiter masses so some very large exoplanets in this orbit range.

https://exoplanetarchive.ipac.caltech.edu/index.html, using this site I found 916 exoplanets. Masses run 0.365 earth masses up to 22.1 Jupiter masses. Plenty to study here and sort out

 

[billslugg]

I can't discern where the ridge is. It's not labelled on the picture. Are they talking about the blob on top of the image?

 

[Helio]

It’s hard to see it without an x-axis using periods. It’s hard to imagine the ridge even exists using that graph.

 

[billslugg]

And what's with the miles? Didn't NASA learn their lesson about mixing units?

 

[Torbjorn Larsson]

The paper suggests the high-eccentricity tidal migration for the ridge based on earlier orbit data (a surplus of elliptical orbits) but also based on comparing their 3-5 days ridge orbital period range with the overlap with the earlier found warm Jupiter ridge pileup.

Comfusingly, the article is mixing planetary classifications. The paper claims that transiting planets, where radius can be estimated, are typically classified in three groups:

small planets (also known as sub-Neptune planets; R_p
< 4 R_⊕), gas giants (also known as Jupiter-size planets; R_p
> 10 R_⊕), and intermediate planets (also known as Neptunian
planets; 4 R_⊕ < R_p < 10 R_⊕).

It is more detailed classifications which uses "super-Earths" to try to discern between terrestrial planets and ice giants such as Neptune.
https://en.wikipedia.org/wiki/List_of_planet_types

It’s hard to see it without an x-axis using periods. It’s hard to imagine the ridge even exists using that graph.

It is an illustration external to the paper, which has much better graphs. I doubt ESA was the source due to the "miles" units, it is typically NASA that tries to inform the US public.

Fig. 2. Distribution of Neptunian planets across the orbital period space, where three regimes are differentiated: a significant deficit of planets at periods ⪅3.2 days (i.e the Neptunian desert), a moderately populated region at periods ⪆5.7 days (i.e. the Neptunian savanna), and an overdensity of planets between these regimes (i.e. the Neptunian ridge). The histogram error bars were computed as the square root of the quadratic sum of the weights.

Fig. A.1 Occurrence of Jupiter-size planets (Rp > 10 R⊕) across the orbital period space. The histogram error bars were computed as the square root of the quadratic sum of the weights.

 

[Helio]

That's impressive. ThanksTorbjorn.

The very short orbital periods, especially for hot Jupiters, is a surprise.

I thought I'd try my hand with separating them by stellar class. [y-axis is radius(Earth)] [I did remove perhaps 5 to 8 outliers per graph.]

It is curious to see the similar patterns.