New planet discovered in proxima centuri system

[insert_name]

A small(~.25) warm planet has been found in orbit around proxima centuri

https://www.sciencealert.com/a-new-planet-a-quarter-of-earth-s-mass-has-been-found-orbiting-the-nearest-star-to-the-sun

[Shpaget]

Quote

But there was another, much fainter signal in the data. There seemed to be something orbiting the star on a five-day period. The signal was so faint, however, that more observations were required to try to work out if it was an external influence, or if the fluctuations in light were emanating from internal processes in the star itself.

It was, indeed, the team determined, an exoplanet; one so tiny that it was causing the star to move back and forth at just 40 centimeters (16 inches) per second. Being able to detect that ever-so-subtle motion from 4.2 light-years away is simply phenomenal.

Capability to detect that motion really is phenomenal.

That being said, 5 day orbit, places it firmly on my Will-Not-Go-To list.

[kerbiloid]

0.25 Earth mass
Another one is 6 Earth mass.

Quarterearth, Quarterneptune

Somebody has applied the 1:4 Solar System mod.

[Rakaydos]

Over twice the mass of mars, 5 times the mass of mercury.

[insert_name]

10 hours ago, Shpaget said:

Capability to detect that motion really is phenomenal.

That being said, 5 day orbit, places it firmly on my Will-Not-Go-To list.

Surprisingly, the equilibrium temperature assuming earthlike regolith is only 87c, hot enough to cook with, but a decent cooling system should keep you nice and raw, though a thick atmosphere could make things worse

[Kerwood Floyd]

I think it's worth noting that this planet is not yet confirmed. 

https://www.syfy.com/syfy-wire/bad-astronomy-proxima-centauri-third-planet-may-have-been-found

 

[Shpaget]

36 minutes ago, insert_name said:

Surprisingly, the equilibrium temperature assuming earthlike regolith is only 87c, hot enough to cook with, but a decent cooling system should keep you nice and raw, though a thick atmosphere could make things worse

Full disclosure, I'm not a Proximadeologist, but my estimate is that such a small planet that close to a star has a snowflakes chance in hell of holding on to anything resembling an atmosphere.

[kerbiloid]

40 minutes ago, Kerwood Floyd said:

I think it's worth noting that this planet is not yet confirmed. 

https://www.syfy.com/syfy-wire/bad-astronomy-proxima-centauri-third-planet-may-have-been-found

 

It's a planet of Schroedinger. It either is, or not. So, we can conditionally celebrate it.

5 minutes ago, Shpaget said:

my estimate is that such a small planet that close to a star has a snowflakes chance in hell of holding on to anything resembling an atmosphere.

Captured hydrogen and native sodium.

Edited February 11, 2022 by kerbiloid

[UmbralRaptor]

The paper is open access: https://www.aanda.org/articles/aa/full_html/2022/02/aa42337-21/aa42337-21.html

Quote

We detect a signal at 5.12 ± 0.04 days with a semi-amplitude of 39 ± 7 cm s⁻¹.

Nice to see that the EPRV systems are hitting target precisions.

Quote

To add to the 67 observations reported in SM2020, we obtained 52 new ESPRESSO spectra of Proxima, for a total of 117 observations spread over 99 individual nights from 2019-02-10 to 2021-05-06.

I think is is a pretty typical number for these spectrographs around M-dwarfs? It sounds in line with those CARMENES (plus some HARPS) planets. The rest of the data analysis (dealing with different offsets, gaussian processes for stellar activity, etc) sounds pretty typical. Please don't ask me about cross-correlation vs template matching.

 

2 hours ago, kerbiloid said:

Captured hydrogen and native sodium.

The hydrogen, helium, sodium, and calcium lines are all from the star, and are fed into the gaussian processes to make sure that stellar activity isn't causing a spurious planet detection, etc.

Quote

To trace the star’s activity, we extract a number of activity indicators from the ESPRESSO spectra or from the CCF. The DRS calculates the CCF’s full width at half maximum (FWHM), contrast (i.e. the relative depth of the CCF), and a shape indicator called CCF asymmetry (see Pepe et al. 2021). Using actin (Gomes da Silva et al. 2018), we also measure activity indices based on the CaII H&K, HeI, Hα, and NaI lines.

No measurement of the planet's atmosphere has been done at this time, and actually doing so would likely be difficult: transiting is doubtful and direct imaging as out as the planet (at 22 marcsec) would be inside the inner working angle of a typical starshade mission.

Quote

With the small stellar radius, Proxima d has a transit probability just above 2%. Its equilibrium temperature may reach 360 K, assuming a Bond albedo of 0.3 (e.g. Seager et al. 2010). From the planetary properties and stellar parameters, we can estimate a planetary radius of 0.81 ± 0.08 R_⊙ using the random forest model from Ulmer-Moll et al. (2019), leading to a transit depth of about 0.3% (approximately half that of Proxima b; Anglada-Escudé et al. 2016). A transit detection would allow a precise measurement of the planetary radius and could place constraints on the planet bulk density and possible atmosphere. However, a transit is unlikely given that Proxima b has not been found to transit (see Jenkins et al. 2019, and references therein) and that transit events at periods below 5 days and depths above 3 mmag have been ruled out (Feliz et al. 2019; Vida et al. 2019).

 

[kerbiloid]

6 hours ago, UmbralRaptor said:

The hydrogen, helium, sodium, and calcium lines are all from the star

The talk was about estimates, and I just refer to Mercury.

https://en.wikipedia.org/wiki/Mercury_(planet)#Surface_conditions_and_exosphere

[Johnmo89]

The planet's equilibrium temperature is around 360 K (87 °C; 188 °F), making it too hot to be habitable.
Small, hot and far... And what benefit can this "great" discovery bring to us?

[Spaceception]

1 hour ago, Johnmo89 said:

The planet's equilibrium temperature is around 360 K (87 °C; 188 °F), making it too hot to be habitable.
Small, hot and far... And what benefit can this "great" discovery bring to us?

Exoplanets can teach us a lot actually. There are only 8 (maybe 9) planets in the solar system, and they don't represent every arrangement for a solar system.

In this case, from the Proxima Centuari system in general, we can start to get an idea of what planetary conditions are like around a red dwarf, from being too close (this planet), in the habitable zone (Proxima b), and being too far (Proxima c, if it exists). It's the closest star to us, and dim to boot, so our instruments will be ready to study it sooner than say, planets around sunlike stars. It's not monumental, but it's still a new interest of study. It also brings home how common planets must be in the universe if some of our nearest neighbors have several.

Beyond that, regardless if planets are potentially habitable, exoplanet studies in general can teach us about:
-Planetary formation studies at different points in a solar system's development
-Worlds we don't see in our solar system, and their conditions (super-Earths, hot jupiters, binary gas giants, planets around binary stars, etc)
-Different planetary conditions we don't see in our solar system often (like Titan's methane seas, what about other fluids?)
-Planetary environments around different star types, and ages - what kind of differences are there between young and old worlds?
-And yes, habitable planets are also a pretty important subject, which stars can life thrive around? How common is it? Could we stumble on unique biosignatures we've only theorized about? How early can life emerge?

But those studies will be in tandem with general exoplanet discoveries, and could even help inform astronomers better when we find potentially habitable worlds. Like what atmosphere compositions are more likely to be natural, or biological? Iirc, oxygen was thought to be biological for a long time, but scientists proposed natural processes that could create a false positive. Learning how to distinguish between those will be important.