From The W.M. Keck Observatory
5.23.24
Mari-Ela Chock (She/Her/Hers)
Communications Officer
808.554.0567
mchock@keck.hawaii.edu
The discovery of a planet similar in size to Venus that’s orbiting a star in the neighborhood of our solar system raises hopes that astronomers may someday unlock the secret to why life appeared on Earth.
An international team of scientists led by the Astrobiology Center (ABC) in Japan, the University of Tokyo, the National Astronomical Observatory of Japan, and Tokyo Institute of Technology found and characterized the planet, called Gliese 12b, based on data from NASA’s TESS space telescope, MuSCAT2 and MuSCAT3 cameras, and three Maunakea Observatories on Hawaiʻi Island: Subaru Telescope, Gemini Observatory, a Program of NSFʻs NOIRLab, and W. M. Keck Observatory.
The planet’s characteristics point to the possibility that the newly-discovered planet may have retained a certain amount of atmosphere, which makes it one of the most suitable targets out of all of the planets discovered thus far to investigate the atmosphere of a Venus-like planet.
The research is published in The Astrophysical Journal Letters.
The study of life in the universe is difficult because we have only one example of a planet where life has been confirmed: Earth. It is difficult to say which characteristics of Earth are required for life to appear, and which are irrelevant. Until we find an “Earth twin” where the conditions for life also appeared, the best astronomers can do is study “evil twins”- planets with initial conditions similar to Earth that turned out very differently, with environments unsuitable for life.
In our solar system, Venus and Mars provide two examples of lifeless “evil twins.” But with only two examples, there is still much uncertainty about how stringent or lax the conditions for life may be. Since the 1990s, more than 5,500 planets orbiting around stars other than the Sun have been discovered. However, most of these planets are hundreds of light years away from Earth, making it challenging to study them in detail.
Gliese 12b, on the other hand, is close to our solar system, located only 40 light-years away. This makes Gliese 12b an ideal target to study with the James Web Space Telescope (JWST) and next generation ground-based telescopes.
“Follow-up observations with JWST and future ground-based observations with 30-meter class telescopes for transit spectroscopy are expected to determine whether Gliese 12b has an atmosphere and whether the atmosphere contains molecular components associated with life such as water vapor, oxygen, and carbon dioxide,” says Masayuki Kuzuhara, a project assistant professor of ABC and lead author of the study.
Although Venus currently does not retain liquid water on the surface, it might have in the past. Likewise, it cannot be fully ruled out that liquid water is present on Gliese 12b’s surface.
Data from Subaru Telescope’s infrared spectrograph (IRD), Keck Observatory’s second generation Near-Infrared Camera (NIRC2) and Gemini North telescope archive data played an important role in confirming that Gliese 12b is in fact a planet; the data ruled out a false positive scenario in which the object Kuzuharaʻs team detected might be a companion star thatʻs part of a binary system where two stars revolve around each other.
Furthermore, the team determined that Gliese 12b is so close to its host star, an M-class red dwarf, that one year on the planet – the time it takes to complete one orbit – lasts only 12.8 Earth days. Its radius is only 4 percent smaller than Earth’s radius, and is less than 3.9 times the mass of our planet. Gliese 12b receives 1.6 times more radiation from its host star than Earth receives from the Sun. For comparison, Venus receives 1.9 times more radiation than Earth.
Based on this data, the team believes that Gliese 12b is an “evil twin,” more like Venus than like Earth. But they cannot rule out the possibility that Gliese 12b is an “Earth twin” with liquid water on its surface. Further observations will determine if Gliese 12b is an “evil twin” or an “Earth twin.” In either case, studying Gliese 12b in finer detail will give a better idea of the prerequisites for a life-friendly environment to develop on a planet.
ABOUT NIRC2
The Near-Infrared Camera, second generation (NIRC2) works in combination with the Keck II adaptive optics system to obtain very sharp images at near-infrared wavelengths, achieving spatial resolutions comparable to or better than those achieved by the Hubble Space Telescope at optical wavelengths. NIRC2 is probably best known for helping to provide definitive proof of a central massive black hole at the center of our galaxy. Astronomers also use NIRC2 to map surface features of solar system bodies, detect planets orbiting other stars, and study detailed morphology of distant galaxies.
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Mission
To advance the frontiers of astronomy and share our discoveries with the world.
The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes on the summit of Maunakea on the Island of Hawai’i feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometer and world-leading laser guide star adaptive optics systems. Keck Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.
Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by The California Association for Research in Astronomy(CARA), whose Board of Directors includes representatives from the California Institute of Technologyand the University of California with liaisons to the board from The National Aeronautics and Space Agency and the Keck Foundation.
Instrumentation
Keck 1
HIRES – The largest and most mechanically complex of the Keck’s main instruments, the High Resolution Echelle Spectrometer breaks up incoming starlight into its component colors to measure the precise intensity of each of thousands of color channels. Its spectral capabilities have resulted in many breakthrough discoveries, such as the detection of planets outside our solar system and direct evidence for a model of the Big Bang theory.
VISIBLE BAND (0.3-1.0 Micron)
MOSFIRE – The Multi-Object Spectrograph for Infrared Exploration gathers thousands of spectra from objects spanning a variety of distances, environments and physical conditions. What makes this huge, vacuum-cryogenic instrument unique is its ability to select up to 46 individual objects in the field of view and then record the infrared spectrum of all 46 objects simultaneously. When a new field is selected, a robotic mechanism inside the vacuum chamber reconfigures the distribution of tiny slits in the focal plane in under six minutes. Eight years in the making with First Light in 2012, MOSFIRE’s early performance results range from the discovery of ultra-cool, nearby substellar mass objects, to the detection of oxygen in young galaxies only 2 billion years after the Big Bang.
Keck 2
DEIMOS – The Deep Extragalactic Imaging Multi-Object Spectrograph is the most advanced optical spectrograph in the world, capable of gathering spectra from 130 galaxies or more in a single exposure. In ‘Mega Mask’ mode, DEIMOS can take spectra of more than 1,200 objects at once, using a special narrow-band filter.
NIRSPEC – The Near Infrared Spectrometer studies very high redshift radio galaxies, the motions and types of stars located near the Galactic Center, the nature of brown dwarfs, the nuclear regions of dusty starburst galaxies, active galactic nuclei, interstellar chemistry, stellar physics, and solar-system science.
ESI – The Echellette Spectrograph and Imager captures high-resolution spectra of very faint galaxies and quasars ranging from the blue to the infrared in a single exposure. It is a multimode instrument that allows users to switch among three modes during a night. It has produced some of the best non-AO images at the Observatory.
KCWI – The Keck Cosmic Web Imager now with KCRM – The Keck Cosmic Web Imager now with the Keck Cosmic Reionization Mapper is designed to provide visible band, integral field spectroscopy with moderate to high spectral resolution, various fields of view and image resolution formats and excellent sky-subtraction. The astronomical seeing and large aperture of the telescope enables studies of the connection between galaxies and the gas in their dark matter halos, stellar relics, star clusters and lensed galaxies.
Keck Cosmic Web Imager on Keck 2 schematic.
NEAR-INFRARED (1-5 Micron)
ADAPTIVE OPTICS – Adaptive optics senses and compensates for the atmospheric distortions of incoming starlight up to 1,000 times per second. This results in an improvement in image quality on fairly bright astronomical targets by a factor 10 to 20.
LASER GUIDE STAR ADAPTIVE OPTICS [pictured above] – The Keck Laser Guide Star expands the range of available targets for study with both the Keck I and Keck II adaptive optics systems. They use sodium lasers to excite sodium atoms that naturally exist in the atmosphere 90 km (55 miles) above the Earth’s surface. The laser creates an “artificial star” that allows the Keck adaptive optics system to observe 70-80 percent of the targets in the sky, compared to the 1 percent accessible without the laser.
NIRC-2/AO – The second generation Near Infrared Camera works with the Keck Adaptive Optics system to produce the highest-resolution ground-based images and spectroscopy in the 1-5 micron range. Typical programs include mapping surface features on solar system bodies, searching for planets around other stars, and analyzing the morphology of remote galaxies.
ABOUT NIRES
The Near Infrared Echellette Spectrograph (NIRES) is a prism cross-dispersed near-infrared spectrograph built at the California Institute of Technology by a team led by Chief Instrument Scientist Keith Matthews and Prof. Tom Soifer. Commissioned in 2018, NIRES covers a large wavelength range at moderate spectral resolution for use on the Keck II telescope and observes extremely faint red objects found with the Spitzer and WISE infrared space telescopes, as well as brown dwarfs, high-redshift galaxies, and quasars.
Now on the KCWI on Keck 2
KCRM – The Keck Cosmic Reionization Mapper will complete the Keck Cosmic Web Imager (KCWI), the world’s most capable spectroscopic imager. The design for KCWI includes two separate channels to detect light in the blue and the red portions of the visible wavelength spectrum. KCWI-Blue was commissioned and started routine science observations in September 2017. The red channel of KCWI is KCRM; a powerful addition that will open a window for new discoveries at high redshifts.
KPF – The Keck Planet Finder (KPF) will be the most advanced spectrometer of its kind in the world. The instrument is a fiber-fed high-resolution, two-channel cross-dispersed echelle spectrometer for the visible wavelengths and is designed for the Keck II telescope. KPF allows precise measurements of the mass-density relationship in Earth-like exoplanets, which will help astronomers identify planets around other stars that are capable of supporting life.
