Santa Cruz de Tenerife (Spain), Jul 22 (EFE).- A study led by the Instituto de Astrofisica de Canarias (IAC), in the Canary Islands, has confirmed the presence of an unusual metal-poor brown dwarf 29 light years away away from the Sun, and its closeness could suggest a possible overabundance of brown dwarfs formed in the early stages of the Milky Way, the IAC has reported.
Several telescopes located at the Roque de Los Muchachos (La Palma) and Calar Alto (Almería) observatories have been used in the investigation, and the results of the study are published in the journal Astronomy and Astrophysics.
An IAC note explains that, on a cosmic scale, “our immediate neighborhood” is made up of just a few hundred stars and brown dwarfs with their own planetary systems.
Unlike stars, brown dwarfs do not have enough mass for hydrogen to fuse inside them, which is the source of energy for stars like the Sun, so they fade over time.
Due to their low luminosity and energy, they are very difficult to detect, but their study is essential to understand the processes of star and planetary formation, the IAC recalls.
The team led by Nicolas Lodieu, an IAC researcher, has carried out a detailed observational study of a metal-poor brown dwarf candidate (it has an atmosphere devoid of substances such as nitrogen and carbon) discovered in 2020.
The study has revealed that this object, called WISE1810 (or WISE J181005.5-101002.3, according to the International Astronomical Union standards) is only 29 light-years away, so it would be part of the immediate solar neighborhood.
Research has also determined that it has a cool surface temperature (525 °C), a luminosity a million times lower than that of the Sun, and a mass in the range of brown dwarfs.
WISE1810 also has very peculiar photometric and spectroscopic properties that will require further investigation since, as Lodieu explains in the note, none of the current atmospheric models can reproduce the light emitted by this peculiar object in a wide range of wavelengths.
The researchers are not aware of an object similar to this one. “We do not see traces of ammonia and methane in near-infrared wavelengths, deducing that the atmosphere has around 3% of the solar chemical composition, but with great uncertainty,” explains María Rosa Zapatero Osorio, a researcher at the Center for Astrobiology (CSIC -INTA) and co-author of the work.
According to the IAC, it is the first time that the presence of such a faint and metal-free object in our galaxy has been confirmed.
“WISE1810 is a world of water vapor because steam and molecular hydrogen are the only strong features that we can see in the spectral energy distribution of the object,” says Professor Eduardo L. Martín of the IAC, also a co-author of the article.
After analyzing the observations, the research team has finally determined that WISE1810 is the closest metal-poor brown dwarf to the solar neighborhood.
Most of these low-metallicity objects formed in the early days of the Milky Way, so the presence of WISE1810 so close to the Sun could suggest a possible overabundance of brown dwarfs formed in the early stages of the Milky Way.
For the research, the OSIRIS, EMIR and HiPERCAM instruments of the Gran Telescopio Canarias (GTC or Grantecan), ALFOSC of the Nordic Optical Telescope (NOT) and Omega2000 of the Calar Alto Astronomical Observatory (CAHA) have been used.
“Future observations could confirm that these types of brown dwarfs are more common than we thought, which will change our view of how stars and brown dwarfs formed in the early Milky Way,” adds Lodieu.
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