Guest essay by Eric Worrall
Proxima Centauri, our closest known stellar neighbour, is packed full of interesting planets. My question – when are we going to send a probe to take a look?
eso2202 — Science Release
New planet detected around star closest to the Sun
10 February 2022
A team of astronomers using the European Southern Observatory’s Very Large Telescope (ESO’s VLT) in Chile have found evidence of another planet orbiting Proxima Centauri, the closest star to our Solar System. This candidate planet is the third detected in the system and the lightest yet discovered orbiting this star. At just a quarter of Earth’s mass, the planet is also one of the lightest exoplanets ever found.
“The discovery shows that our closest stellar neighbour seems to be packed with interesting new worlds, within reach of further study and future exploration,” explains João Faria, a researcher at the Instituto de Astrofísica e Ciências do Espaço, Portugal and lead author of the study published today in Astronomy & Astrophysics. Proxima Centauri is the closest star to the Sun, lying just over four light-years away.
The newly discovered planet, named Proxima d, orbits Proxima Centauri at a distance of about four million kilometres, less than a tenth of Mercury’s distance from the Sun. It orbits between the star and the habitable zone — the area around a star where liquid water can exist at the surface of a planet — and takes just five days to complete one orbit around Proxima Centauri.
The star is already known to host two other planets: Proxima b, a planet with a mass comparable to that of Earth that orbits the star every 11 days and is within the habitable zone, and candidate Proxima c, which is on a longer five-year orbit around the star.
Proxima b was discovered a few years ago using the HARPS instrument on ESO’s 3.6-metre telescope. The discovery was confirmed in 2020 when scientists observed the Proxima system with a new instrument on ESO’s VLT that had greater precision, the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO). It was during these more recent VLT observations that astronomers spotted the first hints of a signal corresponding to an object with a five-day orbit. As the signal was so weak, the team had to conduct follow-up observations with ESPRESSO to confirm that it was due to a planet, and not simply a result of changes in the star itself.
“After obtaining new observations, we were able to confirm this signal as a new planet candidate,” Faria says. “I was excited by the challenge of detecting such a small signal and, by doing so, discovering an exoplanet so close to Earth.”
At just a quarter of the mass of Earth, Proxima d is the lightest exoplanet ever measured using the radial velocity technique,surpassing a planet recently discovered in the L 98-59 planetary system. The technique works by picking up tiny wobbles in the motion of a star created by an orbiting planet’s gravitational pull. The effect of Proxima d’s gravity is so small that it only causes Proxima Centauri to move back and forth at around 40 centimetres per second (1.44 kilometres per hour).
“This achievement is extremely important,” says Pedro Figueira, ESPRESSO instrument scientist at ESO in Chile. “It shows that the radial velocity technique has the potential to unveil a population of light planets, like our own, that are expected to be the most abundant in our galaxy and that can potentially host life as we know it.”
“This result clearly shows what ESPRESSO is capable of and makes me wonder about what it will be able to find in the future,” Faria adds.
ESPRESSO’s search for other worlds will be complemented by ESO’s Extremely Large Telescope (ELT), currently under construction in the Atacama Desert, which will be crucial to discovering and studying many more planets around nearby stars.
More information
This research was presented in the paper “A candidate short-period sub-Earth orbiting Proxima Centauri” (doi:10.1051/0004-6361/202142337) to appear in Astronomy & Astrophysics.
The team is composed of J. P. Faria (Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, Portugal [IA/UPorto], Centro de Astrofísica da Universidade do Porto, Portugal [CAUP] and Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Portugal [FCUP]), A. Suárez Mascareño (Instituto de Astrofísica de Canarias, Tenerife, Spain [IAC], Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain [IAC-ULL]), P. Figueira (European Southern Observatory, Santiago, Chile [ESO-Chile], IA-Porto), A. M. Silva (IA-Porto, FCUP) M. Damasso (Osservatorio Astrofisico di Torino, Italy [INAF-Turin]), O. Demangeon (IA-Porto, FCUP), F. Pepe (Département d’astronomie de l’Université de Genève, Switzerland [UNIGE]), N. C. Santos (IA-Porto, FCUP), R. Rebolo (Consejo Superior de Investigaciones Científicas, Madrid, Spain [CSIC], IAC-ULL, IAC), S. Cristiani (INAF – Osservatorio Astronomico di Trieste, Italy [OATS]), V. Adibekyan (IA-Porto), Y. Alibert (Physics Institute of University of Bern, Switzerland), R. Allart (Department of Physics, and Institute for Research on Exoplanets, Université de Montréal,Canada, UNIGE), S. C. C. Barros (IA-Porto, FCUP), A. Cabral (Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, Portugal [IA-Lisboa], Faculdade de Ciências da Universidade de Lisboa, Portugal [FCUL]), V. D’Odorico (OATS, Institute for Fundamental Physics of the Universe, Trieste, Italy [IFPU], Scuola Normale Superiore, Pisa, Italy) P. Di Marcantonio (OATS), X. Dumusque (UNIGE), D. Ehrenreich (UNIGE), J. I. González Hernández (IAC-ULL, IAC), N. Hara (UNIGE), J. Lillo-Box (Centro de Astrobiología (CAB, CSIC-INTA), Depto. de Astrofísica, Madrid, Spain), G. Lo Curto (European Southern Observatory, Garching bei München, Germany [ESO], ESO-Chile) C. Lovis (UNIGE), C. J. A. P. Martins (IA-Porto, Centro de Astrofísica da Universidade do Porto, Portugal), D. Mégevand (UNIGE), A. Mehner (ESO-Chile), G. Micela (INAF – Osservatorio Astronomico di Palermo, Italy), P. Molaro (OATS), IFPU), N. J. Nunes (IA-Lisboa), E. Pallé (IAC, IAC-ULL), E. Poretti (INAF – Osservatorio Astronomico di Brera, Merate, Italy ), S. G. Sousa (IA-Porto, FCUP), A. Sozzetti (INAF-Turin), H. Tabernero (Centro de Astrobiología, Madrid, Spain [CSIC-INTA]), S. Udry (UNIGE), and M. R. Zapatero Osorio (CSIC-INTA).
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Contacts
João Faria
Instituto de Astrofisica e Ciências do Espaço, Faculdade de Ciências, Universidade do Porto
Porto, Portugal
Tel: +351 226 089 855
Email: joao.faria@astro.up.ptPedro Figueira
ESO and Instituto de Astrofísica e Ciências do Espaço
Santiago, Chile
Tel: +56 2 2463 3074
Email: pedro.figueira@eso.orgNuno Santos
Instituto de Astrofisica e Ciências do Espaço, Faculdade de Ciências, Universidade do Porto
Porto, Portugal
Email: nuno.santos@astro.up.ptMario Damasso
INAF – Osservatorio Astrofisico di Torino
Turin, Italy
Tel: +39 339 1816786
Email: mario.damasso@inaf.itAlejandro Suárez Mascareño
Instituto de Astrofísica de Canarias
Tenerife, Spain
Tel: +34 658 778 954
Email: asm@iac.esBaptiste Lavie
Département d’astronomie de l’Université de Genève
Genève, Switzerland
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We have had the technology to launch an affordable robot interstellar mission since the 1950s.
In the wake of the Hiroshima and Nagasaki nuclear bombs, the Manhattan Scientists were keen to find peaceful uses for nuclear bomb technology. One of their ideas was Project Orion, using nuclear bombs to propel a spaceship.
Their most impressive hypothetical design, using H-Bombs, was just good enough to power a starship (link – search for the term “momentum limited”).
Project Orion focussed on designs which could carry humans. But what if instead of a large spaceship designed to limit acceleration to human tolerance, you built a disintegrating Chinese firecracker of a ship, with an acceleration hardened payload which could take a level of thrust which would turn human astronauts into jelly?
Maybe, just maybe we could take a close look at our nearest neighbour, and figure out if it was worth a second visit.
Update (EW): Renowned physicist Freeman Dyson was one of the lead scientists on Project Orion. Dyson calculated Project Orion had a theoretical top speed of 0.033C, fast enough to reach Proxima Centauri in 133 years, not thousands of years.
Update2 (EW): A few people have mentioned the difficulty of getting a signal back from 4 light years. According to the National Radio Astronomy Observatory, you would need a minimum 1MW radio signal to reach Earth from Proxima. A powerful radio, but not completely beyond imagination. If all else fails, the probe could announce “I made it” by saving a nuclear bomb and using it to power a nuclear pumped laser, a device developed during the Reagan Star Wars program. The US military won’t say how powerful the beam from a nuclear pumped laser is, but I’m guessing its more than a megawatt.
“when are we going to send a probe to take a look?”
circa 2040. Starshot Breakthrough – https://breakthroughinitiatives.org/initiative/3
is developing laser-launched gram-massed lightsail craft for exploring the Proxima Centauri system. The current plan is to launch several thousand probes over the course of a few months, accelerating the probes to approximately 0.2 c. The probes would form clusters and send data back using optical transmission techniques. They would fly through the system and return images and basic environmental data.
we’re looking to develop precursor missions in the next decade for looking at Potentially Hazardous Asteroids and OORT cloud objects.
The full Proxima Centauri mission would require a GW class laser array, with the sails requiring atomic-scale fabrication. The precursor missions can be accomplished with MW class industrial lasers and micrometer scale 3D printing.
Was the pitch for funding accidentally dropped, or did the WUWT moderators do their job?
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Couple your “gram-massed lightsail craft for exploring the Proxima Centauri system” with Eric Worrall’s previously posted comment above that “You’d need a 1MW signal to reach Earth, according to NRAO. A small nuclear reactor could supply the power. It wouldn’t hurt to have a repeating station on the outer edge of the solar system, or possibly another one further out.” and you might just see a slight issue that needs to be fleshed out prior to “circa 2040“.
Anyway, thanks for today’s comedy posting, very enjoyable.
A Red Dwarf that is known to have powerful frequent flares. Not the best candidate for finding life on one of it’s planets I would think.
It always amazes me how many astronomers get paid significant bucks per annum for pursuing a hobby.
A constant 1 g acceleration spacecraft would take 5 years ships time, allowing for deceleration.
A hydrogen fusion engine would need something like 330 thousand tons of fuel for a 100 ton spacecraft.
An anti matter engine would cut fuel requirements to about 3 thousand tons.
Let’s make the investment in FightAging.org first, so the people that launch it get to see the return data.
When did we stop doing projects that lasted more than a lifetime to complete – and have our civilisation been declining ever since?