Cool new worlds found in our cosmic backyard

Date:
August 18, 2020
Source:
Association of Universities for Research in Astronomy (AURA)
Summary:
How complete is our census of the Sun's closest
neighbors? Astronomers and a team of data-sleuthing volunteers
participating in Backyard Worlds: Planet 9, a citizen science
project, have discovered roughly 100 cool worlds near the Sun --
objects more massive than planets but lighter than stars, known as
brown dwarfs. Several of these newly discovered worlds are among
the very coolest known, with a few approaching the temperature of
Earth -- cool enough to harbor water clouds.



FULL STORY ==========================================================================
How complete is our census of the Sun's closest neighbors? Astronomers
using NSF's NOIRLab facilities and a team of data-sleuthing volunteers participating in Backyard Worlds: Planet 9, a citizen science project,
have discovered roughly 100 cool worlds near the Sun -- objects
more massive than planets but lighter than stars, known as brown
dwarfs. Several of these newly discovered worlds are among the very
coolest known, with a few approaching the temperature of Earth -- cool
enough to harbor water clouds.


========================================================================== Discovering and characterizing astronomical objects near the Sun is
fundamental to our understanding of our place in, and the history of,
the Universe. Yet astronomers are still unearthing new residents of the
Solar neighborhood. A remarkable breakthrough was announced today, with
the discovery of roughly 100 cool brown dwarfs near the Sun [1].The new Backyard Worlds discoveries bridge a previously empty gap in the range
of low-temperature brown dwarfs, identifying a long-sought missing link
within the brown dwarf population.

"These cool worlds offer the opportunity for new insights into the
formation and atmospheres of planets beyond the Solar System," said
Aaron Meisner from the National Science Foundation's NOIRLab and the
lead author of the research paper. "This collection of cool brown dwarfs
also allows us to accurately estimate the number of free-floating worlds roaming interstellar space near the Sun." This major advancement was made possible with archival data from the Nicholas U. Mayall 4-meter Telescope
at Kitt Peak National Observatory (KPNO) and the Vi'ctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO), which were
made available through the Community Science and Data Center (CSDC),
all programs of NSF's NOIRLab. Large survey data sets were then made
available to the Backyard Worlds volunteers using NOIRLab's Astro Data
Lab science platform. The results, to be published in TheAstrophysical Journal,demonstrate the rapidly growing role of survey and archival data research in astronomy today.

Brown dwarfs lie somewhere between the most massive planets and the
smallest stars. Lacking the mass needed to sustain nuclear reactions in
their core, brown dwarfs resemble cooling embers. Their low mass, low temperature and lack of internal nuclear reactions make them extremely
faint -- and therefore extremely difficult to detect. Because of this,
when searching for the very coolest brown dwarfs, astronomers can only
hope to detect such objects relatively close to the Sun.

To help find our Sun's coldest and nearest neighbors, the astronomers
of the Backyard Worlds project turned to a worldwide network of more
than 100,000 citizen scientists [2]. These volunteers diligently inspect trillions of pixels of telescope images to identify the subtle movements
of brown dwarfs and planets. Despite the abilities of machine learning
and supercomputers, there's no substitute for the human eye when it
comes to scouring telescope images for moving objects.



==========================================================================
The keen eyes of the Backyard Worlds volunteers have already discovered
more than 1,500 cold worlds near to the Sun, and today's paper presents
roughly 100 of the coldest in that sample. According to Meisner, this is
a record for any citizen science program by a factor of about 20, and
20 citizen scientists are listed as co-authors of the study. A handful
of these cool worlds -- which are among the very coldest brown dwarfs
known -- approach the temperature of Earth.

NASA's Spitzer Space Telescope provided the brown dwarf temperature
estimates [3].

Brown dwarfs are expected to cool as they age, passing from near-stellar temperatures down to planetary temperatures and below, fading all the
while and eventually winking out. The new discoveries attest to this
picture by uncovering elusive examples of brown dwarfs approaching Earth-temperature.

"This paper is evidence that the solar neighborhood is still
uncharted territory and citizen scientists are excellent astronomical cartographers," said co-author Jackie Faherty of the American Museum of
Natural History.

"Mapping the coldest brown dwarfs down to the lowest masses gives us
key insights into the low-mass star formation process while providing a
target list for detailed studies of the atmospheres of Jupiter analogs." Citizen scientist, Astro Data Lab user, and paper co-author Jim Walla
added, "It's awesome to know that our discoveries are now counted
among the Sun's neighbors and will be targets of further research."
Alongside the dedicated efforts of the Backyard Worlds volunteers,
NOIRLab's Astro Data Lab was instrumental in this research. The technical burden of downloading billion-object astronomical catalogs is typically insurmountable for individual investigators -- including most professional astronomers.

"AstroData Lab's open and accessible web portal allowed Backyard Worlds
citizen scientists to easily query massive catalogs for brown dwarf candidates," explained NOIRLab astronomer Stephanie Juneau, who helped introduce the citizen scientists to Astro Data Lab. Astro Data Lab also
enables convenient matching between data sets from NOIRLab telescopes
and external facilities, such as NASA's WISE satellite, that jointly contributed to these brown dwarf discoveries.



==========================================================================
In addition to Astro Data Lab's making data accessible to the
Backyard Worlds collaboration, archival observations by telescopes
at two other NOIRLab Programs -- CTIO and KPNO -- were also key to
this discovery. "Wide-area imaging from NOIRLab's Mayall and Blanco
telescopes was also critical," explained Aaron Meisner. "To select only
the very coldest brown dwarfs, we inspected deep images from a variety
of sensitive astronomical surveys." "It's great to see such thrilling
results from NOIRLab's efforts to broaden participation in astronomy
research," said Chris Davis of the National Science Foundation, the
US agency that supports operations at the Kitt Peak and Cerro Tololo observatories and at CSDC. "By making archival data from NSF's Mayall and Blanco telescopes publicly available and easily accessible through CSDC,
folks with a fascination for astronomy can make a real contribution to
science and to our understanding of the Universe." The approach of the Backyard Worlds project -- searching for rare objects in large data sets
-- is also one of the goals for the upcoming Vera C. Rubin Observatory
[4]. Currently under construction on Cerro Pacho'n in the Chilean Andes,
Rubin Observatory will image the visible sky from the southern hemisphere
every three nights over ten years, providing a vast amount of data that
will enable new ways of doing astrophysical research.

"Vast modern data sets can unlock landmark discoveries, and it's exciting
that these could be spotted first by a citizen scientist," concludes
Aaron Meisner.

"These Backyard Worlds discoveries show that members of the public can
play an important role in reshaping our scientific understanding of our
solar neighborhood." Notes [1] The closest of these new discoveries
is roughly 23 light-years away from the Sun. Many more of these brown
dwarfs are in the 30-60 light-year distance range.

[2]Backyard Worlds: Planet 9 is hosted by Zooniverse.

[3]Complementary follow-up observations were also supplied by Keck
Observatory, Mont Me'gantic Observatory, and Carnegie Institution for
Science's Las Campanas Observatory.

[4]Rubin Observatory and Department of Energy (DOE) Legacy Survey of
Space and Time Camera are operated by NSF's NOIRLab and SLAC National Accelerator Laboratory (SLAC).


========================================================================== Story Source: Materials provided by Association_of_Universities_for_Research_in_Astronomy_ (AURA). Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Aaron M. Meisner, Jacqueline K. Faherty, J. Davy Kirkpatrick,
Adam C.

Schneider, Dan Caselden, Jonathan Gagne, Marc J. Kuchner, Adam J.

Burgasser, Sarah L. Casewell, John H. Debes, Etienne Artigau,
Daniella C.

Bardalez Gagliuffi, Sarah E. Logsdon, Rocio Kiman, Katelyn Allers,
Chih- Chun Hsu, John P. Wisniewski, Michaela B. Allen, Paul
Beaulieu, Guillaume Colin, Hugo A. Durantini Luca, Sam Goodman,
Leopold Gramaize, Leslie K.

Hamlet, Ken Hinckley, Frank Kiwy, David W. Martin, William
Pendrill, Austin Rothermich, Arttu Sainio, Jorg Schumann,
Nikolaj Stevnbak Andersen, Christopher Tanner, Vinod Thakur,
Melina Thevenot, Jim Walla, Zbigniew Wedracki, Christian Aganze,
Roman Gerasimov, Christopher Theissen, The Backyard Worlds:
Planet 9 Collaboration. Spitzer Follow-up of Extremely Cold Brown
Dwarfs Discovered by the Backyard Worlds: Planet 9 Citizen Science
Project. The Astrophysical Journal (accepted), 2020 [abstract] ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200818142137.htm

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