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  • richardmitnick 10:50 pm on July 30, 2021 Permalink | Reply
    Tags: "Astronomers study a hot Jupiter in unprecedented detail thanks to SPIRou!", , , Canada France Hawaii Telescope, , , , , The exoplanet Tau Boötis b and its host star Tau Boötis, USA   

    From Canada France Hawaii Telescope, Mauna Kea Observatory, Hawaii, USA: “Astronomers study a hot Jupiter in unprecedented detail thanks to SPIRou!” 

    From Canada France Hawaii Telescope, Mauna Kea Observatory, Hawaii, USA

    7.28.21

    Media Contact
    Mary Beth Laychak
    director of strategic communications, Canada-France-Hawai’i Telescope
    808-885-3121
    laychak@cfht.hawaii.edu

    Scientific Contacts
    Stefan Pelletier (lead author)
    Ph.D. Candidate, Institute for Research on Exoplanets
    Université de Montréal, Montréal, Canada
    stefan.pelletier@umontreal.ca

    Björn Benneke (co-author)
    Professor, Institute for Research on Exoplanets
    Université de Montréal, Montréal, Canada
    514-578-2716,
    bjorn.benneke@umontreal.ca

    1
    Artistic rendition of the exoplanet Tau Boötis b and its host star, Tau Boötis.
    Image credits: Credit: L. Calçada. European Southern Observatory [Observatoire européen austral][Europäische Südsternwarte] (EU) (CL).

    An international team of astronomers has measured the most precise composition of the hot Jupiter Tau Boötis b’s atmosphere, providing us with a better understanding of giant planets. Using the SPIRou spectropolarimeter at the Canada-France-Hawaii Telescope in Hawaii, a team led by Stefan Pelletier, a PhD student at University of Montréal [Université de Montréal] (CA)‘s Institute for Research on Exoplanets (iREx), studied the atmosphere of the gas giant exoplanet Tau Boötis b, a scorching hot world that takes a mere three days to orbit its host star.

    Their detailed analysis, presented in a paper published today in The Astronomical Journal, shows that the atmosphere of the gaseous planet contains carbon monoxide, as expected, but surprisingly did not identify water, a molecule that was anticipated to be prevalent and should be easily detectable with SPIRou.

    Tau Boötis b is a planet that is 6.24 times more massive than Jupiter and 8 times closer to its parent star than Mercury to the Sun. Its host star, Tau Boötis, located 51 light years from Earth is 40% more massive than the sun and is one of the brightest known planet-bearing stars in the sky.

    Discovered in 1996, Tau Boötis b was one of the first exoplanets ever detected thanks to the radial velocity method. The radial velocity method studies the slight back-and-forth motion of a star generated by the gravitational tug of its planet.

    The planet’s atmospheric composition has been studied a handful of times before, but never with an instrument as powerful as SPIRou.

    “SPIRou’s high resolution and infrared wavelength range open a new window into the atmosphere of planets likeTau Boötis b,” says Dr. Luc Arnold, CFHT resident astronomer and SPIRou instrument scientist. “These are the kinds of observations that the instrument was designed for and we look forward to seeing what SPIRou uncovers next.”

    Studying hot Jupiters to better understand Jupiter and Saturn

    “Hot Jupiters like Tau Boötis b offer an unprecedented opportunity to probe giant planet formation”, said co-author Björn Benneke, astrophysics professor and Pelletier’s PhD supervisor at Université de Montréal. “The composition of the planet gives clues as to where and how this giant planet formed.”

    The key to revealing the formation location and mechanism of giant planets is imprinted in their atmospheric composition. The extreme temperature of hot Jupiters allows most molecules in their atmospheres to be in gaseous form and detectable with current instruments, enabling astronomers to precisely measure the content of their atmospheres.

    “In our Solar System, Jupiter and Saturn are much colder,” continues Benneke. “Some molecules such as water are frozen and hidden deep in their atmospheres. Thus, we have a very poor knowledge of their abundance. Studying exoplanets provides a better way to understand our own giant planets. For example, the low amount of water on Tau boötis b could mean that our own Jupiter is drier than we had previously thought.”

    SPIRou: a unique instrument

    Tau Boötis b is one of the first planets studied with SPIRou, which started observations at CFHT in 2018. SPIRou is an infrared spectropolarimeter which takes the light from a single object and breaks the light into its component infrared colors; colors our eyes are unable to detect. The observations allow astronomers to study the object’s characteristics– temperature, motion, and in the case of Tau Boötis b, the composition of the planet’s atmosphere.

    “This spectropolarimeter can analyze the planet’s thermal light — the light emitted by the planet itself — in an unprecedentedly large range of colours, and with a resolution that allows for the identification of many molecules at once: water, carbon monoxide, methane, etc.” explains iREx researcher Neil Cook, a co-author that is an expert on the SPIRou instrument.

    The team spent 20 hours observing the exoplanet with SPIRou between April 2019 and June 2020. This exquisite dataset allowed the researchers to make a detailed analysis of the molecular content of the hot Jupiter’s atmosphere.

    “We measured the abundance of all major molecules that contain either carbon or oxygen,” explains Pelletier. “Since they are the two most abundant elements in the universe, after hydrogen and helium, that gives us a very complete picture of the content of the atmosphere.”

    Tau Boötis b, like most planets, does not pass in front of its star as it orbits around it, from Earth’s point of view. Previously, the study of exoplanet atmospheres has mostly been limited to these “transiting” planets – those that cause periodic dips in the brightness of their star when they pass between us and the star, blocking some of the light.

    “It is the first time we got such precise measurements on the atmospheric composition of a non-transiting exoplanet. This work opens the dloor to studying in detail the atmospheres of a large number of exoplanets, even those that do not transit their star,” explains PhD student Caroline Piaulet, also a co-author of the study.

    Searching for water

    Assuming a similar composition as in the Solar System, models show that water vapour should be present in large quantities in the atmosphere of an exoplanet similar to Tau Boötis b. It should thus have been easy to detect with an instrument such as SPIRou.

    “We expected a strong detection of water, with maybe a little carbon monoxide,” explains Pelletier. “We were, however, surprised to find the opposite, carbon monoxide, but no water.”

    The team worked hard to make sure the results could not be attributed to problems with the instrument or the analysis of the data.

    “Once we’ve convinced ourselves the content of water was indeed much lower than expected on Tau Boötis b, we were able to start searching for formation mechanisms that could explain this,” says Pelletier.

    A composition similar to Jupiter

    The analysis of Pelletier and colleagues allowed them to conclude that Tau Boötis b’s atmospheric composition has roughly five times as much carbon as that found in the Sun, quantities similar to that measured for Jupiter.

    This may be a hint that hot Jupiters could form much further from their host star, at distances that are similar to the giant planets in our Solar System, and simply experienced a different evolution, which included a migration towards the star.

    “According to what we found for Tau Böotis b, it would seem that, at least composition-wise, hot Jupiters may not be so different from our own Solar System giant planets after all,” concludes Pelletier.

    In addition to Stefan Pelletier, Björn Benneke, Neil Cook and Caroline Piaulet, the team includes Institute for Research on Exoplanets [Institut de recherche sur les exoplanètes]University of Montréal [Université de Montréal] (CA) members Antoine Darveau-Bernier, Anne Boucher, Louis-Philippe Coulombe, Étienne Artigau, David Lafrenière, Simon Delisle, Romain Allart, René Doyon, Charles Cadieux and Thomas Vandal, all based at University of Montréal [Université de Montréal] (CA), and seven other co-authors from France, the United States, Portugal and Brazil.

    Funding was provided by the the Technologies for Exo-Planetary Science (TEPS) CREATE program, the Fonds de recherche du Québec – Nature et technologies (FRQNT), the Natural Sciences and Engineering Research Council of Canada (NSERC), the Trottier Family Foundation and the French National Research Agency (ANR).

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Canada France Hawaii Telescope Observatory (US) hosts a world-class, 3.6 meter optical/infrared telescope. The observatory is located atop the summit of Mauna Kea, a 4200 meter, dormant volcano located on the island of Hawaii, USA.

    The CFH Telescope became operational in 1979. The mission of CFHT is to provide for its user community a versatile and state-of-the-art astronomical observing facility which is well matched to the scientific goals of that community and which fully exploits the potential of the Mauna Kea site.

     
  • richardmitnick 12:21 pm on July 16, 2019 Permalink | Reply
    Tags: , being replaced by LBNL Lux Zeplin project, , ending, , Lead, , , SD, , U Washington LUX Dark matter Experiment at SURF, USA,   

    From Lawrence Berkeley National Lab: “Some Assembly Required: Scientists Piece Together the Largest U.S.-Based Dark Matter Experiment” 

    From Lawrence Berkeley National Lab

    July 16, 2019

    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 486-5582

    Major deliveries in June set the stage for the next phase of work on LUX-ZEPLIN project.

    1
    Lower (left) and upper photomultiplier tube arrays are prepared for LZ at the Sanford Underground Research Facility in Lead, South Dakota. (Credit: Matt Kapust/SURF)

    Most of the remaining components needed to fully assemble an underground dark matter-search experiment called LUX-ZEPLIN (LZ) arrived at the project’s South Dakota home during a rush of deliveries in June.

    When complete, LZ will be the largest, most sensitive U.S.-based experiment yet that is designed to directly detect dark matter particles. Scientists around the world have been trying for decades to solve the mystery of dark matter, which makes up about 85 percent of all matter in the universe though we have so far only detected it indirectly through observed gravitational effects.

    The bulk of the digital components for LZ’s electronics system, which is designed to transmit and record signals from ever-slight particle interactions in LZ’s core detector vessel, were among the new arrivals at the Sanford Underground Research Facility (SURF). SURF, the site of a former gold mine now dedicated to a broad spectrum of scientific research, was also home to a predecessor search experiment called LUX.

    U Washington LUX Dark matter Experiment at SURF, Lead, SD, USA

    A final set of snugly fitting acrylic vessels, which will be filled with a special liquid designed to identify false dark matter signals in LZ’s inner detector, also arrived at SURF in June.

    3
    An intricately thin wire grid is visible (click image to view larger size) atop an array of photomultiplier tube. The components are part of the LZ inner detector. (Credit: Matt Kapust/SURF)

    Also, the last two of four intricately woven wire grids that are essential to maintain a constant electric field and extract signals from the experiment’s inner detector, also called the time projection chamber, arrived in June (see related article).

    LZ achieved major milestones in June. It was the busiest single month for delivering things to SURF — it was the peak,” said LZ Project Director Murdock Gilchriese of the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). Berkeley Lab is the lead institution for the LZ project, which is supported by an international collaboration that has about 37 participating institutions and about 250 researchers and technical support crew members.

    “A few months from now all of the action on LZ is going to be at SURF — we are already getting close to having everything there,” Gilchriese said.

    Mike Headley, executive director at SURF, said, “We’ve been collectively preparing for these deliveries for some time and everything has gone very well. It’s been exciting to see the experiment assembly work progress and we look forward to lowering the assembled detector a mile underground for installation.”

    4
    Components for the LUX-ZEPLIN project are stored inside a water tank nearly a mile below ground. The inner detector will be installed on the central mount pictured here, and acrylic vessels (wrapped in white) will fit snugly around this inner detector. (Credit: Matt Kapust/SURF)

    All of these components will be transported down a shaft and installed in a nearly mile-deep research cavern. The rock above provides a natural shield against much of the constant bombardment of particles raining down on the planet’s surface that produce unwanted “noise.”

    LZ components have also been painstakingly tested and selected to ensure that the materials they are made of do not themselves interfere with particle signals that researchers are trying to tease out.

    LZ is particularly focused on finding a type of theoretical particle called a weakly interacting massive particle or WIMP by triggering a unique sequence of light and electrical signals in a tank filled with 10 metric tons of highly purified liquid xenon, which is among Earth’s rarest elements. The properties of xenon atoms allow them to produce light in certain particle interactions.

    Proof of dark matter particles would fundamentally change our understanding of the makeup of the universe, as our current Standard Model of Physics does not account for their existence.

    Standard Model of Particle Physics (LATHAM BOYLE AND MARDUS OF WIKIMEDIA COMMONS)

    Assembly of the liquid xenon time projection chamber for LZ is now about 80 percent complete, Gilchriese said. When fully assembled later this month this inner detector will contain about 500 photomultiplier tubes. The tubes are designed to amplify and transmit signals produced within the chamber.

    5
    An array of photomultiplier tubes that are designed to detect signals occurring within LZ’s liquid xenon tank. (Credit: Matt Kapust/SURF)

    Once assembled, the time projection chamber will be lowered carefully into a custom titanium vessel already at SURF. Before it is filled with xenon, this chamber will be lowered to a depth of about 4,850 feet. It will be carried in a frame that is specially designed to minimize vibrations, and then floated into the experimental cavern across a temporarily assembled metal runway on air-pumped pucks known as air skates.

    Finally, it will be lowered into a larger outer titanium vessel, already underground, to form the final vacuum-insulated cryostat needed to house the liquid xenon.

    That daylong journey, planned in September, will be a nail-biting experience for the entire project team, noted Berkeley Lab’s Simon Fiorucci, LZ deputy project manager.

    “It will certainly be the most stressful — this is the thing that really cannot fail. Once we’re done with this, a lot of our risk disappears and a lot of our planning becomes easier,” he said, adding, “This will be the biggest milestone that’s left besides having liquid xenon in the detector.”

    Project crews will soon begin testing the xenon circulation system, already installed underground, that will continually circulate xenon through the inner detector, further purify it, and reliquify it. Fiorucci said researchers will use about 250 pounds of xenon for these early tests.

    Work is also nearing completion on LZ’s cryogenic cooling system that is required to convert xenon gas to its liquid form.

    6
    Researchers from the University of Rochester in June installed six racks of electronics hardware that will be used to process signals from the LZ experiment. (Credit: University of Rochester)

    LZ digital electronics, which will ultimately connect to the arrays of photomultiplier tubes and enable the readout of signals from particle interactions, were designed, developed, delivered, and installed by University of Rochester researchers and technical staff at SURF in June.

    “All of our electronics have been designed specifically for LZ with the goal of maximizing our sensitivity for the smallest possible signals,” said Frank Wolfs, a professor of physics and astronomy at the University of Rochester who is overseeing the university’s efforts.

    He noted that more than 28 miles of coaxial cable will connect the photomultiplier tubes and their amplifying electronics – which are undergoing tests at UC Davis – to the digitizing electronics. “The successful installation of the digital electronics and the online network and computing infrastructure in June makes us eager to see the first signals emerge from LZ,” Wolfs added.

    Also in June, LZ participants exercised high-speed data connections from the site of the experiment to the surface level at SURF and then to Berkeley Lab. Data captured by the detectors’ electronics will ultimately be transferred to LZ’s primary data center, the National Energy Research Scientific Computing Center (NERSC) at Berkeley Lab via the Energy Sciences Network (ESnet), a high-speed nationwide data network based at Berkeley Lab.

    NERSC

    NERSC Cray Cori II supercomputer at NERSC at LBNL, named after Gerty Cori, the first American woman to win a Nobel Prize in science

    NERSC Hopper Cray XE6 supercomputer


    LBL NERSC Cray XC30 Edison supercomputer


    The Genepool system is a cluster dedicated to the DOE Joint Genome Institute’s computing needs. Denovo is a smaller test system for Genepool that is primarily used by NERSC staff to test new system configurations and software.

    NERSC PDSF


    PDSF is a networked distributed computing cluster designed primarily to meet the detector simulation and data analysis requirements of physics, astrophysics and nuclear science collaborations.

    Future:

    Cray Shasta Perlmutter SC18 AMD Epyc Nvidia pre-exascale supeercomputer

    NERSC is a DOE Office of Science User Facility.

    The production of the custom acrylic tanks (see related article), which will contain a fluid known as a liquid scintillator, was overseen by LZ participants at University of California,Santa Barbara.

    5
    The top three acrylic tanks for the LUX-ZEPLIN outer detector during testing at the fabrication vendor. These tanks are now at the Sanford Underground Research Facility in Lead, South Dakota. (Credit: LZ Collaboration)

    “The partnership between LZ and SURF is tremendous, as evidenced by the success of the assembly work to date,” Headley said. “We’re proud to be a part of the LZ team and host this world-leading experiment in South Dakota.”

    NERSC and ESnet are DOE Office of Science User Facilities.

    Major support for LZ comes from the DOE Office of Science, the South Dakota Science and Technology Authority, the U.K.’s Science & Technology Facilities Council, and by collaboration members in the U.S., U.K., South Korea, and Portugal.

    More:

    For information about LZ and the LZ collaboration, visit: http://lz.lbl.gov/

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    LBNL campus

    Bringing Science Solutions to the World
    In the world of science, Lawrence Berkeley National Laboratory (Berkeley Lab) is synonymous with “excellence.” Thirteen Nobel prizes are associated with Berkeley Lab. Seventy Lab scientists are members of the National Academy of Sciences (NAS), one of the highest honors for a scientist in the United States. Thirteen of our scientists have won the National Medal of Science, our nation’s highest award for lifetime achievement in fields of scientific research. Eighteen of our engineers have been elected to the National Academy of Engineering, and three of our scientists have been elected into the Institute of Medicine. In addition, Berkeley Lab has trained thousands of university science and engineering students who are advancing technological innovations across the nation and around the world.

    Berkeley Lab is a member of the national laboratory system supported by the U.S. Department of Energy through its Office of Science. It is managed by the University of California (UC) and is charged with conducting unclassified research across a wide range of scientific disciplines. Located on a 202-acre site in the hills above the UC Berkeley campus that offers spectacular views of the San Francisco Bay, Berkeley Lab employs approximately 3,232 scientists, engineers and support staff. The Lab’s total costs for FY 2014 were $785 million. A recent study estimates the Laboratory’s overall economic impact through direct, indirect and induced spending on the nine counties that make up the San Francisco Bay Area to be nearly $700 million annually. The Lab was also responsible for creating 5,600 jobs locally and 12,000 nationally. The overall economic impact on the national economy is estimated at $1.6 billion a year. Technologies developed at Berkeley Lab have generated billions of dollars in revenues, and thousands of jobs. Savings as a result of Berkeley Lab developments in lighting and windows, and other energy-efficient technologies, have also been in the billions of dollars.

    Berkeley Lab was founded in 1931 by Ernest Orlando Lawrence, a UC Berkeley physicist who won the 1939 Nobel Prize in physics for his invention of the cyclotron, a circular particle accelerator that opened the door to high-energy physics. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab legacy that continues today.

    A U.S. Department of Energy National Laboratory Operated by the University of California.

    University of California Seal

    DOE Seal

     
  • richardmitnick 5:52 pm on January 3, 2018 Permalink | Reply
    Tags: , , , , Rattlesnake Ridge: a large failure forming in Washington State, USA   

    From AGU: “Rattlesnake Ridge: a large failure forming in Washington State, USA” 

    AGU bloc

    American Geophysical Union

    3 January 2018
    Dave Petley

    Rattlesnake Ridge is a large hillside located above the I-82 highway to the south of the town of Yakima in Washington State, NW USA. The Google Earth image below shows the location of the site (at 46.524, -120.467), taken in May 2017. The image is looking towards the east – note the large active quarry on the south side of the ridge, and other signs of earlier (and smaller scale) excavation on the slope. Note also the proximity of the slope to I-82.

    1
    Google Earth image of the incipient landslide at Rattlesnake Ridge

    In October 2017 a major fissure started to develop through Rattlesnake Ridge. Over the last three months this apparent tension crack has widened to encompass a volume of about 3 million cubic metres. KXLY has this image providing a perspective of the size of the block that is on the move at Rattlesnake Ridge:-

    3
    Image of the slope failure at Rattlesnake Ridge, via KXLY

    Whilst the best impression of the feature can be seen in this Youtube video by Steven Mack

    This view of the feature is perhaps the most interesting, showing how the crack extends into the rear face of the quarry.

    4

    The latest reports suggest that the crack is widening at a rate of about 30 cm per week at present. Interestingly KIMA TV reports that the expectation is that the slope will self-stabilise:

    Senior Emergency Planner Horace Ward said they have not determined a cause yet and said it’s just nature. Ward said the ridge is being monitored and they think the slide will stop itself.

    “It could continue to move slowly enough to where it kind of just keeps spilling a little bit of material into the quarry until it creates a toe for itself to stop and stabilize the hillside,” he said.

    The implication of this is that it is a rotational slip. However, the tension crack has quite a complex structure, with some evidence of the development of a graben structure:-

    5
    The trension crack at Rattlesnake Ridge. Still from a Youtube video by Steven Mack

    Combined with the potential for weakening the materials controlling the deformation, this makes forecasting the likely future behaviour of this slope quite challenging, but of course it is the geologists on the ground who are best placed to make a judgement. In the short to medium term high resolution monitoring is the right approach.

    Many thanks to the various people who highlighted this one to me, and provided links. Your help is very much appreciated.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The purpose of the American Geophysical Union is to promote discovery in Earth and space science for the benefit of humanity.

    To achieve this mission, AGU identified the following core values and behaviors.

    Core Principles

    As an organization, AGU holds a set of guiding core values:

    The scientific method
    The generation and dissemination of scientific knowledge
    Open exchange of ideas and information
    Diversity of backgrounds, scientific ideas and approaches
    Benefit of science for a sustainable future
    International and interdisciplinary cooperation
    Equality and inclusiveness
    An active role in educating and nurturing the next generation of scientists
    An engaged membership
    Unselfish cooperation in research
    Excellence and integrity in everything we do

    When we are at our best as an organization, we embody these values in our behavior as follows:

    We advance Earth and space science by catalyzing and supporting the efforts of individual scientists within and outside the membership.
    As a learned society, we serve the public good by fostering quality in the Earth and space science and by publishing the results of research.
    We welcome all in academic, government, industry and other venues who share our interests in understanding the Earth, planets and their space environment, or who seek to apply this knowledge to solving problems facing society.
    Our scientific mission transcends national boundaries.
    Individual scientists worldwide are equals in all AGU activities.
    Cooperative activities with partner societies of all sizes worldwide enhance the resources of all, increase the visibility of Earth and space science, and serve individual scientists, students, and the public.
    We are our members.
    Dedicated volunteers represent an essential ingredient of every program.
    AGU staff work flexibly and responsively in partnership with volunteers to achieve our goals and objectives.

     
  • richardmitnick 10:15 am on May 29, 2017 Permalink | Reply
    Tags: , , , , , Citizen scientists in search of failed stars, , , NASA Infrared Telescope facility Mauna Kea, , USA   

    From astrobites: “Citizen scientists in search of failed stars” 

    Astrobites bloc

    Astrobites

    May 29, 2017
    Ingrid Pelisoli

    Title: The First Brown Dwarf Discovered by the Backyard Worlds: Planet 9 Citizen Science Project
    Authors: Marc J. Kuchner, Jacqueline K. Faherty, Adam C. Schneider et al.
    First Author’s Institution: NASA Goddard Space Flight Center, Exoplanets and Stellar Astrophysics Laboratory

    Status: Accepted to ApJL [open access]

    Not everyone can be a star. Brown dwarfs, for example, have failed on their attempt.

    Artist’s concept of a Brown dwarf [not quite a] star. NASA/JPL-Caltech

    These objects have masses below the necessary amount to reach pressure and temperature high enough to burn hydrogen into helium in their cores and thus earn the classification “star”. It’s not very long since we’ve learned of their existence. They were proposed in the 1960s by Dr. Shiv S. Kumar, but the first one was only observed many years later, in 1988 – and we are not even sure it is in fact a brown dwarf! We’ve only reached a substantial number of known brown dwarfs with the advent of infrared sky surveys, such as the Two Micron All Sky Survey (2MASS) and the Wide-field Infrared Survey Explorer (WISE).


    Caltech 2MASS Telescopes, a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC) at Caltech, at the Whipple Observatory on Mt. Hopkins south of Tucson, AZ, and at the Cerro Tololo Inter-American Observatory near La Serena, Chile.

    NASA/WISE Telescope

    Discovering and characterising cold brown dwarfs in the solar neighbourhood is one of the primary science goals for WISE. There are two ways of doing that: 1) identifying objects with the colours of cold brown dwarfs; 2) identifying objects with significant proper motion. Brown dwarfs are relatively faint objects, so they need to be nearby to be detected. We can detect the movement of such nearby targets against background stars, which are so distant that they appear to be fixed on the sky. This movement is called proper motion. As the signal-to-noise ratio is not very good for such faint objects, the second method is the preferred one. However, single exposure WISE images are not deep enough to find most brown dwarfs. This is where today’s paper enters. The authors have launched a citizen science project called “Backyard Worlds: Planet 9” to search for high proper motion objects, including brown dwarfs and possible planets orbiting beyond Pluto, in the WISE co-add images. Co-add images are simply a sum of the single exposures images taking into account corrections to possible shifts between them. This increases signal-to-noise ratio and helps to detect faint targets. On today’s paper, they report the first discovery of their project: a new brown dwarf in the solar neighbourhood, which was identified only six days after the project was launched!

    Citizen science: a promising approach

    The idea behind citizen science is to engage numerous volunteers to tackle research problems that would otherwise be impractical or even impossible to accomplish. The Zooniverse community hosts lots of such projects, in disciplines ranging from climate science to history. Citizen science projects have made some remarkable discoveries in astronomy, such as KIC 8462852 (aka “Tabby’s Star”, “Boyajian’s star” or “WTF star”).

    3
    Tabby’s Star is mysteriously dimming again as reported by Fairborn Observatory in Arizona.
    (Photo : Unexplained/YouTube screenshot)

    In “Backyard Worlds: Planet 9”, volunteers are asked to examine short animations composed of difference images constructed from time-resolved WISE co-adds. The difference images are obtained subtracting the median of two subsequent images from the image to be analysed. This way, if an object does not significantly move, it will disappear from the analysed image with the subtraction, leaving only moving objects to be detected. The images are also divided into tiles small enough to be analysed on a laptop or cell phone screen. The classification task consists in viewing one animation, which is composed of four images, and identifying candidates for two types of moving objects: “movers” and “dipoles”. Movers are fast moving sources, that travel more than their apparent width over the course of WISE’s 4.5 year baseline. Dipoles are slower-moving sources that travel less than their apparent width, so that there will be a negative image right next to a positive image, since the subtraction of the object’s flux will only be partial. An online tutorial is provided to show how to identify such objects and distinguish them from artifacts such as partially subtracted stars or galaxies, and cosmic rays.

    The discovery: WISEA 1101+5400

    4
    Figure 1: Two co-adds of WISE data separated by 5 years showing how WISEA 1101+5400 has moved. The region shown is 2.0” x 1.6” in size. [Figure 2 from the paper]

    Five users reported a dipole on a set of images, which can be seen here, the first report taking place only six days after the project was launched. The object, called WISEA 1101+5400, can be seen on Figure 1. This source would be undetectable in single exposure images, while in these co-adds it is visible and obviously moving. Follow-up spectra were obtained 9 using the SpeX spectrograph on the 3 m NASA Infrared Telescope Facility (IRTF).

    NASA Infrared Telescope facility Mauna Kea, Hawaii, USA

    The average spectrum is shown on Figure 2. Both the object’s colours and the obtained spectra are consistent with a field T dwarf, a type of brown dwarf.

    5
    Figure 2: In black, the spectrum for WISEA 1101+5400. A field T5.5 brown dwarf, SDSS J0325+0425, is shown in red for comparison. Atomic and molecular opacity sources that define the T dwarf spectral class are indicated. [Figure 3 from the paper]

    Assuming WISEA 1101+5400 is the worst case scenario, i.e. about as faint an object as this survey is able to detect and with the minimum detectable proper motion, the authors estimate that “Backyard Worlds: Planet 9” has the potential to discover about a hundred new brown dwarfs. If WISEA 1101+5400 is not the worst case scenario, but objects even fainter or with lower proper motion can be found, this number could go up.

    Although the discovery of only one brown dwarf might not seem worthy of celebration, this discovery demonstrates the ability of citizen scientists to identify moving objects much fainter than the WISE single exposure limit. It is yet another proof that science could use the help of enthusiasts. So if you’re not doing anything now, why not take your pick at https://www.zooniverse.org/ and help a scientist?

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
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