From W.M. Keck Observatory: “Direct Image of Newly-discovered Brown Dwarf Captured”

Keck Observatory, two 10 meter telescopes operated by Caltech and the University of California, Maunakea Hawaii USA, altitude 4,207 m (13,802 ft).

From W.M. Keck Observatory

December 11, 2020

Astronomers using two Maunakea Observatories – Subaru Telescope and W. M. Keck Observatory – have discovered a key benchmark brown dwarf orbiting a Sun-like star just 86 light-years from Earth that provides a key reference point for understanding the properties of the first directly-imaged exoplanets.

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level.

NAOJ Subaru SCExAO CHARIS [Coronagraphic High Angular Resolution Imaging Spectrograph]

Subaru Telescope first detected and captured remarkably sharp pictures of the object. The team conducted follow-up observations at Subaru Telescope to take more direct images as well as at Keck Observatory to obtain infrared images and confirmed the object is an orbiting companion to the star HD 33632 Aa, and not an unrelated background star. Combined with complementary data from the Gaia space astrometry satellite, the researchers also found the brown dwarf has a mass of about 46 Jupiters.

ESA (EU)/GAIA satellite .

Named HD 33632 Ab, the brown dwarf is one of only a few known objects of its kind orbiting a near-twin of the Sun at near-twin scales of our Solar System (Mercury to Pluto).

The study recently published in the November 30, 2020 issue of The Astrophysical Journal Letters.

Brown dwarfs are a class of objects that are smaller than stars but more massive than giant planets like Jupiter. They’re dubbed ‘failed stars’ because they’re not massive enough to ignite nuclear fusion in their cores and shine like true stars.

The team snapped pictures of the HD 33632 system using powerful adaptive optics (AO) technology at both Maunakea Observatories – Subaru Telescope’s state-of-the art exoplanet imaging system, SCExAO/CHARIS, and Keck Observatory’s advanced AO paired with its Near-Infrared Camera (NIRC2) [below]. These technologies remove the atmospheric blurring that distorts astronomical images, resulting in sharper images.

Subaru Telescope data showed the brown dwarf’s atmosphere may contain water and carbon monoxide.

“Thanks to SCExAO/CHARIS’s incredibly sharp images, we can not only see HD 33632 Ab but get ultra-precise measurements for its position and its spectrum, which gives important clues about its atmospheric properties and its dynamics,” said Thayne Currie, an affiliated researcher at Subaru Telescope and lead author of this study.

HD 33632 Ab provides critical new insight into the atmospheres of the planets in HR 8799 – the very first extrasolar system to have its picture taken – since its temperature is likely very similar, though it is older, has a higher mass, and has higher gravity.

“Keck Observatory’s NIRC2 thermal infrared data allowed us to better understand how HD 33632 Ab’s atmosphere compares to those of the first directly imaged exoplanets, HR 8799 bcde, which were discovered in part by Keck,” said Currie.

By studying HD 33632 Ab and the HR 8799 exoplanets, astronomers hope to learn more about how atmospheric conditions of planets and brown dwarfs are tied to the diversity of their age and compositions, such as mass, temperatures, and chemical properties.

See the full W.M. Keck article here .
See the NAOJ Subaru press release here.

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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 Mauna Kea on the Island of Hawaii 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 Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.

Keck UCal


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.

Keck High-Resolution Echelle Spectrometer (HIRES), at the Keck I telescope.

LRIS – The Low Resolution Imaging Spectrograph is a faint-light instrument capable of taking spectra and images of the most distant known objects in the universe. The instrument is equipped with a red arm and a blue arm to explore stellar populations of distant galaxies, active galactic nuclei, galactic clusters, and quasars.

UCO Keck LRIS on Keck 1.

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/MOSFIRE on Keck 1, Mauna Kea, Hawaii, USA.

OSIRIS – The OH-Suppressing Infrared Imaging Spectrograph is a near-infrared spectrograph for use with the Keck I adaptive optics system. OSIRIS takes spectra in a small field of view to provide a series of images at different wavelengths. The instrument allows astronomers to ignore wavelengths where the Earth’s atmosphere shines brightly due to emission from OH (hydroxl) molecules, thus allowing the detection of objects 10 times fainter than previously available.

Keck OSIRIS on Keck 1

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.

Keck/DEIMOS on Keck 2.

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.

NIRSPEC on Keck 2.

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.

KECK Echellette Spectrograph and Imager (ESI) on Keck II.

KCWI – The Keck Cosmic Web Imager 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.

Keck Cosmic Web Imager on Keck 2.

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.

UCO Keck Laser Guide Star Adaptive Optics,Keck Observatory.

LASER GUIDE STAR ADAPTIVE OPTICS – 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.

Keck NIRC2 Camera on Keck 2.


Keck Near-Infrared Echellette Spectrometer on Keck 2.

Future Instrumentation

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.

KCRM – Keck Cosmic Reionization Mapper KCRM on Keck 2.

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.

KPF Keck Planet Finder on Keck 2