WISE J080822.18-644357.3, also called J0808, is a 45 Myr old

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

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, ...

in the

Carina constellation Carina ( ) is a constellation in the southern sky. Its name is Latin for the keel of a ship, and it was the southern foundation of the larger constellation of Argo Navis (the ship ''Argo'') until it was divided into three pieces, the other two be ...

with a circumstellar debris disk orbiting an M-type

red dwarf ''Red Dwarf'' is a British science fiction comedy franchise created by Rob Grant and Doug Naylor, which primarily consists of a television sitcom that aired on BBC Two between 1988 and 1999, and on Dave since 2009, gaining a cult following. T ...

about 331

lightyear A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. On October 21, 2016,

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

Goddard Space Flight Center The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C. in Greenbelt, Maryland, United States. Established on May 1, 1959 as NASA's first space flight center, GSFC empl ...

announced that its

citizen science Citizen science (CS) (similar to community science, crowd science, crowd-sourced science, civic science, participatory monitoring, or volunteer monitoring) is scientific research conducted with participation from the public (who are sometimes re ...

project,

Disk Detective Disk Detective is the first NASA-led and funded-collaboration project with Zooniverse. It is NASA's largest crowdsourcing citizen science project aiming at engaging the general public in search of stars, which are surrounded by dust-rich circ ...

, discovered a debris disk around J0808, using the WISE telescope, a M5.5V dwarf with significant

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 ...

excess at both 12 and 22

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

. Classified as

Peter Pan disk A Peter Pan disk is a circumstellar disk around a star or brown dwarf that appears to have retained enough gas to form a gas giant planet for much longer than the typically assumed gas dispersal timescale of approximately 5 million years. Several ...

number AWI0005x3s in the project database—or 5x3s for short—a BANYAN II Bayesian analysis revealed (with 93.9% probability) the star's

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

as 20.6 ± 1.4 km/ s, associating it with Carina's ∼45

Myr The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...

old young

moving group In astronomy, stellar kinematics is the Observational astronomy, observational study or measurement of the kinematics or motions of stars through space. Stellar kinematics encompasses the measurement of stellar Velocity, velocities in the Milky W ...

. Since most M-dwarf debris disks fade in less than 30 million years, this would be the oldest M dwarf debris disk detected in a moving group, implying a change in understanding of constraint in M-dwarf debris disk evolution. A follow-up study with an optical spectrum obtained with the ANU Siding Spring 2.3 meter telescope showed a Li-rich M5-star with strong

Hα H-alpha (Hα) is a specific deep-red visible spectral line in the Balmer series with a wavelength of 656.28 nm in air and 656.46 nm in vacuum; it occurs when a hydrogen electron falls from its third to second lowest energy level. H-alpha ...

emission. The data is consistent with a low

accretion Accretion may refer to: Science * Accretion (astrophysics), the formation of planets and other bodies by collection of material through gravity * Accretion (meteorology), the process by which water vapor in clouds forms water droplets around nucl ...

of 10⁻¹⁰ yr ⁻¹.

ALMA Alma or ALMA may refer to: Arts and entertainment * ''Alma'' (film), a 2009 Spanish short animated film * ''Alma'' (Oswald de Andrade novel), 1922 * ''Alma'' (Le Clézio novel), 2017 * ''Alma'' (play), a 1996 drama by Joshua Sobol about Alma ...

observations did not detect any

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 ...

, but unresolved 1.3 mm dust emission was detected. Observations with

CTIO The Cerro Tololo Inter-American Observatory (CTIO) is an astronomical observatory located on Cerro Tololo in the Coquimbo Region of northern Chile, with additional facilities located on Cerro Pachón about to the southeast. It is approximately ...

showed a strong flare and variations in the Paschen-β and Brackett-γ lines, which is a clear sign of accretion.

Debris disk

The fitting of a modeled disk with the

Spectral Energy Distribution A spectral energy distribution (SED) is a plot of energy versus frequency or wavelength of light (not to be confused with a 'spectrum' of flux density vs frequency or wavelength). It is used in many branches of astronomy to characterize astron ...

of J0808 indicates a disk temperature of about 263 K (-10

°C The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The ...

or 14

°F The Fahrenheit scale () is a temperature scale based on one proposed in 1724 by the physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit (symbol: °F) as the unit. Several accounts of how he originally defined his ...

). The follow-up study found that a single disk had a poor match with the 22 μm data. The researchers found a better match with a "warm" outer disk with a temperature of about 240 K (-33 °C or -28 °F) and a "hot" inner disk with a temperature of about 1100 K (827 °C or 1520 °F). The warm outer disk is located around 0.115 au and the hot inner disk is located around 0.0056 au. The hot inner disk is likely the source of accreted material. The temperature of the inner disk is comparable to temperatures where

amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal. Etymology The term comes from the Greek ''a'' ("wi ...

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 ...

s anneal into

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

line form. The inner disk also lies near the

Roche limit In celestial mechanics, the Roche limit, also called Roche radius, is the distance from a celestial body within which a second celestial body, held together only by its own force of gravity, will disintegrate because the first body's tidal forc ...

of the red dwarf and therefore the inner disk could be the result of disrupted

planetesimal Planetesimals are solid objects thought to exist in protoplanetary disks and debris disks. Per the Chamberlin–Moulton planetesimal hypothesis, they are believed to form out of cosmic dust grains. Believed to have formed in the Solar System a ...

s. The warm outer disk could be similar to dust belts seen around B- to K-type stars, which have temperatures around 190 K and which likely represent small dust grains of sublimating

ice Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaq ...

from icy

detected a third component with a temperature of 20 K (-253 °C or -424 °F). Using this temperature the researchers were able to estimate the dust mass to 0.057±0.006 . This is higher than the disk mass around ~20

old AU Microscopii and the ~50 Myr old GJ 182, but smaller than the ~10 Myr old TWA 7. The disk has a radius smaller than 16 au. The missing CO detection is explained with two possible scenarios: Either dust grains are released in a collisional cascade induced by the collisions of km-sized planetesimals or a recent collision of planetary bodies generated a large amount of small dust grains. A light curve from

shows variations, which could be disk material blocking light from the star. The

TESS Tess or TESS may refer to: Music * Tess (band), a Spanish pop band active from 2000 to 2005 * TESS (musician), a UK musician Film and theatre * ''Tess'' (1979 film), a 1979 film adaptation of '' Tess of the d'Urbervilles'' * ''Tess'' (2016 film) ...

light curve shows aperiodic dipping on timescales of 0.5–2 days.

Peter Pan disks

Other stars and brown dwarfs were discovered to be similar to J0808, with signs of youth while being in an older moving group. Together with J0808, these older low-mass accretors in nearby moving groups are being called

Gallery

Peter Pan Disk (SED).png, Spectral Energy Distribution (SED) of J0808 (from Disk Detective talk page)

References

External links

AWI0005x3s talk page
at diskdetective.org {{Stars of Carina M-type main-sequence stars Circumstellar disks Carina (constellation) WISE objects Astronomical objects discovered in 2016

Debris disk

Peter Pan disks

Gallery

See also

References

External links