The NASA news conference to present new findings on exoplanets is in progress now around 1:30 PM EST. NASA just published a summary of the findings at www.nasa.gov/...
As somewhat expected, the announcement is about the discovery of new exoplanets, seven earth-sized ones, around the star TRAPPIST-1, 39 light years away. The discovery was made by a team of researchers using NASA's Spitzer Space Telescope and other ground-based telescopes.
Three of these planets are located in the habitable zone (aka known as the Goldilocks zone), where a rocky planet is most likely to have liquid water. The others are close enough that they hold the promise of supporting water.
From the authors of the paper —
Here we report the results of a photometric monitoring campaign of that star from the ground and space. Our observations reveal that at least seven planets with sizes and masses similar to those of Earth revolve around TRAPPIST-1. The six inner planets form a near-resonant chain, such that their orbital periods (1.51, 2.42, 4.04, 6.06, 9.1 and 12.35 days) are near-ratios of small integers. This architecture suggests that the planets formed farther from the star and migrated inwards. Moreover, the seven planets have equilibrium temperatures low enough to make possible the presence of liquid water on their surfaces.
Here is a video from NASA of the findings -
TRAPPIST-1
Early last year, Michaël Gillon (the lead author of the paper) and his group at the University of Liege, using the TRAPPIST telescope (TRAnsiting Planets and PlanetesImals Small Telescope) at ESO’s La Silla Observatory, discovered the planetary system, 39 light years away in the constellation of Aquarius, containing three Earth-sized planets around an ultracool young red dwarf star slightly bigger than Jupiter in size, known as TRAPPIST-1. reflexions.ulg.ac.be/…
Assisted by several ground-based telescopes, including the European Southern Observatory's Very Large Telescope, Spitzer confirmed the existence of two of these planets and discovered five additional ones, increasing the number of known planets in the system to seven.
TRAPPIST-1, a red dwarf star, is much smaller than our Sun — it has 8% the mass and 11% the radius of our Sun. It is also quite cool compared to our Sun (2550 K vs 5778 K); liquid water can survive on planets orbiting very close to it.
Quick note — at the speed of the New Horizons spacecraft, about 59,000 km/h, it will take approximately 714 thousand years to get there and 39 years for a signal to reach back to us.
The Seven Wonders of TRAPPIST-1
All seven of the TRAPPIST-1 planetary orbits are closer to their host star than Mercury is to our sun. The planets also are very close to each other. The orbital periods are relatively short — 1.5 to 12 Earth days. The planets are named TRAPPIST-1b through TRAPPIST-1h.
The planets may also be tidally locked to their star, which means the same side of the planet is always facing the star, therefore each side is either perpetual day or night. This could mean they have weather patterns totally unlike those on Earth, such as strong winds blowing from the day side to the night side, and extreme temperature changes. Alternatively, the perpetual night zone would be cold enough to freeze the main gases of their atmospheres, leaving the daylight zone barren and dry. On the other hand, recent theories propose that either a thick atmosphere or planetary ocean could potentially circulate heat around such a planet. Alternatively, a moon in orbit around the planet may be habitable. It would circumvent the tidal lock problem with its star by becoming tidally locked to its planet. In this manner there would be a day/night cycle as the moon orbited its primary, and hence a more uniform distribution of heat.
Also, red dwarf stars are subject to frequent, intense flares that can strip away the atmospheres of such planets.
Planet Hunting
The exoplanets and their properties were determined based on repeated observations of dips in the star’s light output caused by each of the seven planets passing in front of it — events known as transits, which occur if the orbital planes are serendipitously oriented such that Earth lies close to the extended plane. Exoplanets are also detected by measurements of wobbles of the star caused by orbiting planets.
Besides the NASA Spitzer Space Telescope, the team used many ground-based facilities:
More info, images and videos at www.eso.org/...
Exoplanets
Exoplanets are planets that orbit stars other than our Sun. As of 15 February 2017, there are 3,577 confirmed exoplanets in 2,687 planetary systems. en.wikipedia.org/…
The observable universe is estimated to contains 2 trillion galaxies, each containing 100 billion stars on average. Astronomers estimate 100 billion habitable Earth-like planets in our galaxy the Milky Way, 50 sextillion (50x1021) in the observable universe. www.extremetech.com/…
We wrote about TRAPPIST-1 and other exoplanet systems yesterday in the diary www.dailykos.com/…
Remarks
The news might be a bit disappointing to folks who were expecting an announcement about the discovery of life (none of course on these pages). But lead author Michael Gillon calls them "The seven wonders of TRAPPIST-1”. He stated that "It is also the best target yet for studying the atmospheres of potentially habitable, Earth-size worlds."
"This is the most exciting result I have seen in the 14 years of Spitzer operations," said Sean Carey, manager of NASA's Spitzer Science Center at Caltech/IPAC in Pasadena, California. "Spitzer will follow up in the fall to further refine our understanding of these planets so that the James Webb Space Telescope can follow up. More observations of the system are sure to reveal more secrets.”
References
- These seven alien worlds could help explain how planets form — www.nature.com/…
- Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1 — www.nature.com/…
- NASA announcement — www.nasa.gov/…
- ESO news release — www.eso.org/…
- NASA to Host News Conference on Exoplanets — www.dailykos.com/…
- The James Webb Space Telescope — www.dailykos.com/…
- Red Dwarf — en.wikipedia.org/...