Aizawl, May 25: A team of astronomers from Mizoram University and Physical Research Laboratory (PRL), Ahmedabad, along with international collaborators, has discovered and characterised a rare high-mass transiting brown dwarf named TOI-7154b orbiting a Sun-like star.
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| Graphical data and observational imaging related to the newly discovered high-mass brown dwarf TOI-7154b, published by researchers from Mizoram University and PRL Ahmedabad in The Astronomical Journal. |
The
discovery was led by Associate Professor Dr. Lalthakimi Zadeng from the
Department of Physics, Mizoram University, and Prof. Abhijit Chakraborty from
PRL Ahmedabad. The findings have been published in the latest issue of The
Astronomical Journal.
According
to the research team, TOI-7154b was initially identified as a possible
exoplanet candidate through observations made by NASA’s Transiting Exoplanet
Survey Satellite (TESS). Its true substellar nature was later confirmed using
high-precision radial velocity observations from the PARAS-2 spectrograph
mounted on the 2.5-metre telescope at PRL’s Mount Abu Observatory in Rajasthan.
Additional observations were carried out using the TRES spectrograph at the
Tillinghast Reflector telescope in Arizona, United States.
Scientists
said the combined observations helped accurately determine the object’s mass,
orbit and physical characteristics.
Brown
dwarfs are considered rare celestial objects that fall between giant planets
and stars. They are massive enough to undergo limited deuterium fusion but not
massive enough to sustain hydrogen fusion like normal stars.
The host
star TOI-7154 is described as a metal-rich G-type main-sequence star with
properties similar to the Sun. Its companion, TOI-7154b, completes an orbit
around the host star every 8.86 days in a highly eccentric orbit.
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Researchers
noted that although the brown dwarf has a radius smaller than Jupiter, it
possesses an extremely high mass of nearly 72 Jupiter masses, placing it close
to the hydrogen-burning boundary that separates brown dwarfs from low-mass
stars.
The team
stated that the discovery highlights the growing capabilities of Indian
astronomical instrumentation and precision radial velocity science. They said
the PARAS-2 spectrograph, regarded as one of Asia’s highest-resolution
stabilised radial velocity instruments, played a crucial role in confirming the
brown dwarf’s nature.
The system is estimated to be between 4 and 7 billion years old. Scientists believe TOI-7154b could provide valuable insights into the poorly understood transition region between massive brown dwarfs and very low-mass stars, as well as help researchers study the mysterious “brown dwarf desert” - a rare population of brown dwarfs orbiting stars at close distances.
