Notre Dame physicists discover rare brown dwarf, essential for testing theoretical models | News | Notre Dame News | University of Notre Dame Skip To Content Skip To Navigation Skip To Search University of Notre Dame Notre Dame News Experts ND in the News Subscribe About Us Home Contact Search Menu Home › News › Notre Dame physicists discover rare brown dwarf, essential for testing theoretical models Notre Dame physicists discover rare brown dwarf, essential for testing theoretical models Published: April 06, 2016 Author: Gene Stowe A team led by Justin Crepp has discovered HD 4747 B, a rare brown dwarf. As a new mass, age and metallicity benchmark, HD 4747 B will serve as a laboratory for precision astrophysics to test theoretical models. A team led by Justin Crepp, the Frank M. Freimann Assistant Professor of Physics at the University of Notre Dame, has discovered a rare brown dwarf, a faint object with properties in between that of a star and planet. In addition to taking its picture for the first time, Crepp’s team also determined the brown dwarf’s mass, age and composition — essential information that can be used to “benchmark” the study of these elusive objects. Brown dwarfs are objects thought to have initially begun the process of forming a star but were somehow interrupted before they accumulated sufficient mass and core pressure to ignite nuclear fusion — the process by which the Sun ultimately releases energy in the form of light. An important developmental bridge between bona fide stars and exoplanets, brown dwarfs are very difficult to study because their faint glow fades with time due to a lack of sustained nuclear reactions. The discovery of the object, which goes by the name HD 4747 B, was facilitated by 18 years of precise spectral measurements of the star that indicated it hosts an orbiting companion. “We suspect that these companions form at the same time and from the same material,” Crepp said. “As such, you can infer physical properties of the brown dwarf from its parent star, like age and composition. There are no other objects for which we know the mass, age and the metallicity simultaneously and also independent of the light that the companion gives off. We can therefore use HD 4747 B as a test-bed to study brown dwarfs, enabling precision astrophysics studies for a directly imaged substellar object.” In the past, brown dwarf masses have been estimated using theoretical evolutionary models. Crepp’s team instead calculated the mass of HD 4747 B directly using observations of its orbit in an attempt to help refine brown dwarf models. It is expected that this work will in turn help to inform models for extrasolar planets. Based on a three-dimensional orbit analysis, HD 4747 B has a mass of about 60 Jupiters (a mass of 80 Jupiters is required to ignite nuclear fusion), well below the theoretical estimate of 72 Jupiters, although still within uncertainties. Forthcoming measurements acquired by Crepp’s team will provide yet more stringent tests of the models used by astronomers for brown dwarfs. “This field is transitioning from ‘Hey, I found something neat’ to ‘Hey, I know the mass to within a few percent.’ Now, we can test theoretical models,” Crepp said. The team detected the object using the Keck telescopes in Hawaii, and published their results in a paper describing the discovery. The study has been submitted to the Astrophysical Journal. Co-authors of the study include Erica Gonzales and Eric Bechter, both in the Department of Physics at the University of Notre Dame; Benjamin Montet at the Harvard-Smithsonian Center for Astrophysics and the California Institute of Technology; John Asher Johnson at the Harvard-Smithsonian Center for Astrophysics; Danielle Piskorz at the Division of Geological and Planetary Sciences at the California Institute of Technology; Andrew Howard at the Institute for Astronomy at the University of Hawaii; and Howard Isaacson at the University of California Berkeley. Contact: Justin Crepp, 574-631-4092, jcrepp@nd.edu Posted In: Research Home Experts ND in the News Subscribe About Us Related October 05, 2022 Astrophysicists find evidence for the presence of the first stars October 04, 2022 NIH awards $4 million grant to psychologists researching suicide prevention September 29, 2022 Notre Dame, Ukrainian Catholic University launch three new research grants September 27, 2022 Notre Dame, Trinity College Dublin engineers join to advance novel treatment for cystic fibrosis September 22, 2022 Climate-prepared countries are losing ground, latest ND-GAIN index shows For the Media Contact Office of Public Affairs and Communications Notre Dame News 500 Grace Hall Notre Dame, IN 46556 USA Facebook Twitter Instagram YouTube Pinterest © 2022 University of Notre Dame Search Mobile App News Events Visit Accessibility Facebook Twitter Instagram YouTube LinkedIn