VHS J125601.92–125723.9 (abbreviated to VHS J1256–1257) is a young triple

brown dwarf Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most ...

system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment (systems), environment, is described by its boundaries, ...

located in the constellation

Corvus ''Corvus'' is a widely distributed genus of medium-sized to large birds in the family Corvidae. It includes species commonly known as crows, ravens and Rook (bird), rooks. The species commonly encountered in Europe are the carrion crow, the hoo ...

approximately from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

. The system consists of the equal-mass binary VHS J1256–1257AB and the distant planetary-mass companion VHS 1256–1257 b. In 2022, a continuous radio emission from the radiation belts surrounding VHS J1256–1257 was detected.

VHS 1256–1257 b

VHS 1256–1257 b was first identified and documented by the

2MASS The Two Micron All-Sky Survey, or 2MASS, was an astronomical survey of the whole sky in infrared light. It took place between 1997 and 2001, in two different locations: at the U.S. Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona, and ...

survey in 2015. It orbits at a distance of AU and has an estimated mass of approximately Jupiter masses. The planet is carbon-rich, with a C/O

molar ratio In chemistry, the mole fraction or molar fraction (''xi'' or ) is defined as unit of the amount of a constituent (expressed in moles), ''ni'', divided by the total amount of all constituents in a mixture (also expressed in moles), ''n''tot. This ex ...

exceeding 0.63, and its temperature has been measured at 1380 K. VHS 1256-1257 b's rotation period has been measured to be 22.04 ± 0.05 hours, which is unusually long for

substellar object A substellar object, sometimes called a substar, is an astronomical object the mass of which is smaller than the smallest mass at which hydrogen fusion can be sustained (approximately 0.08 solar masses). This definition includes brown dwarfs and fo ...

Spectroscopy

Observations with Hubble Wide-Field Camera 3 near-infrared

time-series In mathematics, a time series is a series of data points indexed (or listed or graphed) in time order. Most commonly, a time series is a sequence taken at successive equally spaced points in time. Thus it is a sequence of discrete-time data. Exa ...

spectroscopic observations showed that VHS 1256 b varied with 19.3% at 1.1 and 1.7 μm over 8.5 hours. With the 1.27 μm filter the amplitude was even higher at 24.7%. This is the largest amplitude for any substellar object as of 2022, placing it in the

mid-infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

. Later studies with the Hubble space telescope have yielded even higher brightness variability of 33-37% without a definite period, indicating a presence of both spots and waves.

Atmospheric composition

The atmosphere of VHS 1256 b is in a chemical disequilibrium.

Carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...

naturally reacts with

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

molecules in the atmosphere of brown dwarfs, forming

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...

and

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

molecules. The reaction works in both ways, meaning that methane reacts with water and releases hydrogen and carbon monoxide. At higher temperatures and lower pressure the reaction is tilted towards carbon monoxide and at lower temperatures and higher pressure the reaction is tilted towards methane. At equilibrium a cold brown dwarf or planet should have a high concentration of methane and a low concentration of carbon monoxide. The presence of carbon monoxide and depleted methane in the spectrum of VHS 1256 b compared to equilibrium atmospheric models suggests atmospheric mixing. The vertical mixing causes carbon monoxide to rise from lower and hotter atmospheric layers and methane to sink into these lower layers, forcing the upper atmosphere in chemical disequilibrium. Water and

carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...

have both been detected in the atmosphere. The JWST observed the planet in 2022 by taking spectra at a wavelength of 1-20 μm with the instruments

NIRSpec The NIRSpec (Near-Infrared Spectrograph) is one of the four scientific instruments flown on the James Webb Space Telescope (JWST). The JWST is the follow-on mission to the Hubble Space Telescope (HST) and is developed to receive more information ...

and

MIRI ) , subdivision_type = Country , subdivision_name = , subdivision_type1 = State , subdivision_name1 = , subdivision_type2 = Division , subdivision_name2 ...

. The team analysing the data found

water vapor (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapor, water vapour or aqueous vapor is the gaseous pha ...

, methane, carbon monoxide,

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...

potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...

and

silicate In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is al ...

clouds within the atmosphere of VHS 1256 b. The direct detection of silicate clouds is the first such detection reported for a

planetary-mass object A planetary-mass object (PMO), planemo, or planetary body is by geophysical definition of celestial objects any celestial object massive enough to achieve hydrostatic equilibrium (to be rounded under its own gravity), but not enough to sustain ...

. The silicates are thought to be made of small amorphous silicate particles. The silicate feature in VHS 1256 b closely matches the silicate feature in the L4.5 brown dwarf 2M2224-0158, detected with Spitzer. The grain size and composition of the silicate clouds in VHS 1256 b will be modelled in the future.

References

External links

Planet VHS 1256-1257 b
''

Extrasolar Planets Encyclopaedia The Extrasolar Planets Encyclopaedia is an astronomy website, founded in Paris, France at the Meudon Observatory by Jean Schneider in February 1995, which maintains a database of all the currently known and candidate extrasolar planets, with indi ...

'', 14 April 2020
A New Spin to Solving Mystery of Stellar Companions
Rebecca Johnson,

McDonald Observatory McDonald Observatory is an astronomical observatory located near unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Locke in the Davis Mountains of West Texas, with additional facil ...

, 4 December 2017 {{DEFAULTSORT:VHS J1256-1257 Corvus (constellation) Triple star systems Brown dwarfs M-type brown dwarfs L-type brown dwarfs Astronomical objects discovered in 2015 J12560215-1257217 TIC objects Planetary systems with one confirmed planet