Astronomers discover widest separation of brown dwarf pair to date


Date:
February 17, 2022
Source:
W. M. Keck Observatory
Summary:
A team of astronomers has discovered a rare pair of brown dwarfs
that has the widest separation of any brown dwarf binary system
found to date.

They're 12 billion miles apart, or three times the separation
of Pluto from the Sun. The discovery is exceptional considering
brown dwarf binaries share a weaker gravitational force than binary
stars with the same separation, and thus are more likely to break
up over time.



FULL STORY ==========================================================================
A team of astronomers has discovered a rare pair of brown dwarfs that
has the widest separation of any brown dwarf binary system found to date.


========================================================================== "Because of their small size, brown dwarf binary systems are usually
very close together," said Emma Softich, an undergraduate astrophysics
student at the Arizona State University (ASU) School of Earth and Space Exploration and lead author of the study. "Finding such a widely separated
pair is very exciting." The gravitational force between a pair of brown
dwarfs is lower than for a pair of stars with the same separation,
so wide brown dwarf binaries are more likely to break up over time,
making this pair of brown dwarfs an exceptional find.

The study, which is based on observations the University of California San Diego (UC San Diego) Cool Star Lab conducted with W. M. Keck Observatory
on Maunakea, Hawai'i Island, is published in today's issue of The
Astrophysical Journal Letters.

Using Keck Observatory's Near-Infrared Echellette Spectrometer, or NIRES instrument, members of the UC San Diego Cool Star Lab, including Physics Professor Adam Burgasser and graduate students Christian Aganze and
Dino Hsu, obtained infrared spectra of the brown dwarf binary system,
called CWISE J014611.20-050850.0AB. The data revealed the two brown
dwarfs are about 12 billion miles apart, or three times the separation
of Pluto from the Sun. This distance confirms the unusual brown dwarf
couple breaks the record for having the widest separation from each other.

"Keck's exceptional sensitivity in the infrared with this instrument
was critical for our measurements," said co-author Burgasser, who
leads the Cool Star Lab. "The secondary brown dwarf of this system is exceptionally faint, but with Keck we were able to obtain good enough
spectral data to classify both sources and identify them as members
of a rare class of blue L dwarfs." "Wide, low-mass systems like CWISE J014611.20-050850.0AB are usually disrupted early on in their lifetimes,
so the fact that this one has survived until now is pretty remarkable,"
said co-author Adam Schneider of the U.S. Naval Observatory, Flagstaff
Station and George Mason University.



========================================================================== Brown dwarfs are celestial objects that are smaller than a normal
star. These objects are not massive enough to sustain nuclear fusion
and shine like normal stars, but are hot enough to radiate energy.

Many brown dwarfs have been discovered with data from NASA's Wide-field Infrared Survey Explorer (WISE) via the Backyard Worlds: Planet 9 citizen science project, which solicits help from the public to search the WISE
image data bank to find brown dwarfs and low-mass stars, some of the
Sun's nearest neighbors.

For this study, the researchers inspected images of Backyard Worlds discoveries, where companion brown dwarfs may have been overlooked. In
doing so, they discovered the rare CWISE J014611.20 050850.0AB brown
dwarf binary system.

Softich went through about 3,000 brown dwarfs from Backyard Worlds one
by one and compared the WISE images to other survey images, looking for evidence of a brown dwarf companion to the original target. The team
then used data from the Dark Energy Survey (DES) to confirm that it was
indeed a brown dwarf pair.

They then used Keck Observatory's NIRES to confirm the brown dwarfs have spectral types L4 and L8, and that they are at an estimated distance
of about 40 parsecs, or 130.4 light-years from Earth, with a projected separation of 129 astronomical units, or 129 times the distance between
the Sun and the Earth.

The team hopes this discovery will allow astronomers the chance to study
brown dwarf binary systems and to develop models and procedures that
will help in recognizing more of them in the future.

"Binary systems are used to calibrate many relations in astronomy, and
this newly discovered pair of brown dwarfs will present an important test
of brown dwarf formation and evolution models," said co-author Jennifer Patience, Softich's adviser at ASU.

========================================================================== Story Source: Materials provided by W._M._Keck_Observatory. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Emma Softich, Adam C. Schneider, Jennifer Patience, Adam
J. Burgasser,
Evgenya Shkolnik, Jacqueline K. Faherty, Dan Caselden, Aaron
M. Meisner, J. Davy Kirkpatrick, Marc J. Kuchner, Jonathan Gagne',
Daniella Bardalez Gagliuffi, Michael C. Cushing, Sarah L. Casewell,
Christian Aganze, Chih- Chun Hsu, Nikolaj Stevnbak Andersen,
Frank Kiwy, Melina The'venot. CWISE J014611.20-050850.0AB: The
Widest Known Brown Dwarf Binary in the Field.

The Astrophysical Journal Letters, 2022; 926 (2): L12 DOI:
10.3847/2041- 8213/ac51d8 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220217141238.htm

--- up 10 weeks, 5 days, 7 hours, 13 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)