Burgasser publishes on issues of inclusion in Nature Astronomy

Cool Star Lab PI Adam Burgasser recently published two Comments in Nature Astronomy, in a special issue focused on diversity, equity and inclusion in physical science.

The first Comment, “Why I Teach Growth Mindset“, led by Adam, discusses the concept of mindset, and how fixed mindset can amplify the struggles of marginalized students, mentees and peers in Astronomy and Physics. He describes how he addresses fixed mindset in workshops and in the classroom, and provides a toolkit for hosting a Growth Mindset workshop.

The second Comment, “Toward inclusive practices with indigenous knowledge“, led by Aparna Venakatesan, describes models of partnership with indigenous communities that integrate collaboration with integrity. Inspired by the 2015 Indigenous Worldviews in Informal Science Education conference, examples featured include Cosmic SerpentA Hua He InoaEnVision MaunakeaNative Universe, and Maunakea Scholars. This comment is based on a more detailed white paper submitted to the Astro2020 Decadal Review.

The Comments and Perspectives contributed to the Nature Astronomy issue are free to read and download until early January 2020; copies of these articles are also available on request to Adam.

Citizen Scientist Discovers Dusty Debris Disk Around White Dwarf

Citizen scientist Melina Thévenot of Germany helped the Backyard Worlds/Planet 9 program discover a unique white dwarf with a dusty debris disk, and observations made by Cool Star Lab members with the Keck/NIRES instrument were critical its confirmation. The work, led by STScI astronomer John Debes, was reported in Astrophysical Journal Letters today.

Since 2017, the Backyard Worlds project has been engaging citizen scientists to search through data from NASA’s WISE mission to identify overlooked stars in the vicinity of the Sun. These have mostly been cold brown dwarfs, of which the project has found more than 1,000 too date – more than one a day! But it also picks up other dim, red things, in this case the white dwarf LSPM J0207+3331.

White dwarfs are normally “blue” due to their high surface temperatures (they are after all the cores of spent stars), but this white dwarf is surrounded by a complex disk of dusty debris, likely the result of the tidal disruption of an orbiting planet or asteroid (the same process is likely responsible for the rings around Saturn and other giant planets). This disk, heated by the white dwarf, glows in the infrared, allowing it to show up in WISE. While tidal debris disks aren’t new around white dwarfs (Cool Star Lab’s Carl Melis is specialist in this area), both the structure of this disk—which appears to be made of several distinct ring-like components—and that age of the white dwarf are surprising.

Very little was known about J0207+3331 prior to its identification by Melina in the Backyard Worlds program; only one prior paper had identified it as a high proper motion star. After an initial attempt to measure its spectrum was foiled by bad weather, it was therefore up to Cool Star Lab members Adam Burgasser & Jon Rees to get the necessary spectral data. Using the newly-commissioned NIRES instrument on Keck (during admittedly more not so great weather), Adam & Jon managed to measure the near-infrared spectrum of the source, which was largely consistent with a hot blackbody with slight uptick at the red end. This tiny bit of near-infrared excess, and the much greater mid-infrared excess in WISE photometry, could arise from several things, including an unseen brown dwarf companion (much like the first L dwarf ever discovered, GD 165B). However, we were able to show that the combined NIRES spectrum and WISE photometry were inconsistent with any white dwarf-brown dwarf combination, leaving a debris disk as the best model. (For once, Adam was happy not to find a brown dwarf!)

(Left) Analysis of our NIRES spectrum shows that any brown dwarf companion to J0207+0331 would be too small (blue dots) compared to model predictions to reproduce the observed excess, which rules out the binary model. (Right) instead, a model that includes a single white dwarf (orange line) and a debris ring system (red dashed line) can fit both spectral and photometric data (from Debes et al. 2019)

The NIRES spectrum, which contains several weak Hydrogen lines, allowed our team to determine the temperature and surface gravity of the white dwarf, and in turn its mass (0.69±0.02 solar masses) and age (3.0±0.2 billion years). By combining all of the data together, our team was also able to generate a model for the disk, which requires more than one “ring” of material with a total mass greater than a typical asteroid or comet. Both of these features are surprising: structure in the ring suggests there may be another body clearing a gap in the disk, or perhaps there have been two tidal disruption events that happened sequentially. This dust should also be cleared our “relatively” quickly (“relatively” = few 100 million years), requiring a “relatively” recent disruption.

Overall, the properties of J0207+3331 suggest that planetary systems may be continuously dismantled for billions of years after a star dies, which gives us a lot more time to study the innards of planets after tidal dissection (yech!). Moreover, the discovery of such an interesting, and relatively nearby system (only 45 parsecs, or 150 light-years, away), means that there may be many more such systems out there. Plenty of opportunity for future citizen scientists like Melina Thévenot!

Here are some links to press reports on this result:

NASA: https://www.nasa.gov/feature/goddard/2019/citizen-scientist-finds-ancient-white-dwarf-star-encircled-by-puzzling-rings

NOAO: https://www.noao.edu/news/2019/pr1904.php

UCSD: https://ucsdnews.ucsd.edu/pressrelease/astronomers_invite_citizens_to_crowd_source_new_worlds

ASU: https://asunow.asu.edu/20190219-discoveries-citizen-science-finds-ancient-white-dwarf-star

CNN: https://www.cnn.com/2019/02/19/world/white-dwarf-rings-discovery/index.html

Backyard Worlds Blog, where Melina Thévenot describes her discovery: https://blog.backyardworlds.org/2019/02/19/the-crystal-ball-white-dwarf/

Want to find your own new world? Give Backyard Worlds/Planet 9 a try! https://www.zooniverse.org/projects/marckuchner/backyard-worlds-planet-9

Adam Burgasser awarded a Fulbright Scholarship

Cool Star Lab PI Adam Burgasser has been awarded a 2017-2018 Fulbright Scholarship to conduct astrophysical research in the United Kingdom. Adam will be in residence at the University of Exeter Department of Astrophysics during the Fall of 2017, working with Exeter colleagues to investigate cloud formation in the atmospheres of the coolest stars, brown dwarfs and extrasolar planets.

The Fulbright Program was initiated by Senator J. William Fulbright in 1946 and is managed by the US Department of State. It aims to increase mutual understanding and support of friendly and peaceful relations between people of the US and the people of other countries by awarding exchange grants to US and foreign researchers in over 155 countries. Over 370,000 Fulbright Awards have been awarded since the programs inception, and many have gone on to win Nobel Prizes and become leaders and innovators in scientific research.

Cool Star Lab Presents Work at 2016 Physics Education Research Conference

Mike Lopez, Isabela Rodrigues and Adam Burgasser presented their early analysis of an experimental Physics course at the 2016 Physics Education Research Conference in Sacramento, CA. This was the first PERC for all three researchers. In addition, former Cool Star Lab member Dianna Cowern was on hand for the overlapping American Association of Physics Teachers (AAPT) meeting presenting her work on the Physics Girl video series.

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Past and present Cool Star Lab members at the 2016 PERC; from left to right: Isabela Rodrigues, Dianna Cowern, Adam Burgasser and Mike Lopez.

The primary research presentations focused on analysis of an experiment conducted in Fall 2015 to implement Cooperative Problem Solving (CPS) in the large Physics 1A Introductory Mechanics course. The current course format, which is lecture-based, does not specifically build up students’ problem solving skills, skills that students often struggle with and which may benefit them more in their other majors and in their future careers. Inspired by work being done by Thomas Gredig at CSU Long Beach, I implemented a form of CPS as described in Heller & Heller (2010) as a flipped-format course, with online video lectures providing the primary instruction and class time primarily devoted to problem-solving skills and techniques.  To validate the model, Adam taught 9 sections of the CPS course with 1 (large) section of interactive lecture. The work presented at the PERC was a preliminary analysis of student outcomes.

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Adam Burgasser receives Distinguished Teaching Award

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Cool Star Lab PI Adam Burgasser has been awarded a UCSD Distinguished Teaching Award for 2016. He was nominated by the Physics Department’s Education Vice Chair Tom Murphy, and recognized for his broad contributions to the educational mission at UCSD; efforts to develop interdisciplinary courses between Physics, humanities and the arts; and commitment to student learning.

From the nomination:

Adam J. Burgasser has shown tremendous dedication to education in a diverse set of classes, teaching a broad array of students. His commitment has been epic; the connection he has forged with students has been profound; and his activism to increase the quality of the UC San Diego community is extremely admirable. As one student described, Professor Burgasser has “a uniquely genuine and passionate interest for his students to succeed, for UC San Diego to thrive, and for physics to be as tangible a topic as any other; he embodies the type of physics professor other professors should strive to become.”   Professor Burgasser not only has acted as a successful ambassador of physics to students on our campus but also has built educational bridges to a variety of points beyond campus.