Astronomers Discover One of the Oldest and Densest Brown Dwarfs Orbiting an Ancient Milky Way Star
Harvard-Smithsonian Team Reports Rare Brown Dwarf Discovery
Astronomers from the Harvard-Smithsonian Centre for Astrophysics (CfA), together with international partners, have announced the discovery of a powerful new brown dwarf roughly 60 times heavier than Jupiter. The object, named TOI-7019 b, orbits a star belonging to the Milky Way's ancient thick disk. The discovery is outlined in a study published on 5 December on the arXiv preprint server.
Readers following major breakthrough in astronomy and space science can find related discoveries and cosmic research coverage at FSNews365, which regularly reports on astrophysics and exoplanet science.
In Between Planets and Stars
Why Brown Dwarfs Are So Unusual
Brown dwarfs (BDs) occupy a curious middle ground between planets and stars, with masses ranging from 13 to 80 times that of Jupiter, or roughly 0.012 to 0.076 solar masses. While astronomers have identified many brown dwarfs over the years, examples found orbiting other stars remain notably rare.
In a recent study, a team led by Jea Adams Redai of the Harvard-Smithsonian Centre for Astrophysics (CfA) reported the discovery of another such uncommon object, a brown dwarf companion to the star TOI-7019. The star was first observed by NASA's Transiting Exoplanet Survey Satellite (TESS), which detected a transit signal in its light curve. Subsequent observations confirmed that the signal is caused by a substellar companion.
"Using follow-up photometry and radial-velocity measurements, we determined the physical properties of this companion, which turns out to be a dense brown dwarf," the researchers noted.
Massive and Dense Brown Dwarf Characteristics
The study reports that the newly identified brown dwarf (BD) has a radius of roughly 0.82 times that of Jupiter radii and a mass about 61.3 times greater, resulting in an extraordinary density of 141.7 g/cm³. It completes an orbit around its host star every 48.26 days at a distance of around 0.25 astronomical units (AU), with an estimated equilibrium temperature of 479 kelvin (K).
Its host, TOI-7019, is a main-sequence star close in size to the Sun but less massive, at about 0.78 solar masses. Estimated to be 12 billion years old, it is an ancient, metal-poor star belonging to the Milky Way's thick disc, with an effective temperature of approximately 5,800 kelvin.
Related space discoveries and science updates
For broader context on how ancient cosmic environments shape planetary systems, environmental and long-term planetary evolution topics are explored at Earth Day Harsh Reality.
First Known Case in the Milky Way's Thick Disc
As a result, TOI-7019 b stands out as the first known transiting brown dwarf to orbit a star belonging to the Milky Way's ancient thick disc. It is also the oldest brown dwarf observed transiting a main-sequence star for which scientists have been able to determine such a precise age.
Astronomers also found that TOI-7019 b's radius is around 12.3% larger than predicted by standard evolutionary models for old, metal-poor brown dwarfs, underscoring the need to refine substellar models to account for varying elemental abundances.
Environmental and cosmic history context
Future Observational Prospects With James Webb
Why TOI-7019 b Is a Prime Target
In summarizing their findings, the researchers emphasized that TOI-7019 b represents a promising target for future atmospheric studies. Observations with the James Webb Space Telescope (JWST), they noted, could determine whether molecular signatures such as water vapour, methane and carbon monoxide differ from those seen in solar-metallicity brown dwarfs of comparable mass and temperature, although separating metallicity effects from other atmospheric factors would be demanding.
Discussions on how space discoveries may influence long-term scientific and human understanding of the universe are also examined at Human Health Issues, particularly where space science intersects with future human exploration.
Comments
Post a Comment