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Monday Science Seminar
Date: Monday, November 23rd
Time: 12:00 pm
Place: Zoom:
Speaker: Goni Halevi (Princeton) and Theron Carmichael (Harvard CfA)
Abstract: Goni Halevi:
I’ll be talking about the interplay of MHD turbulence and nuclear burning in accretion disks formed by disrupted white dwarfs. This has relevance to binary systems that may contribute to optical transients and future gravitational waves sources.

Theron Carmichael:
Title: The search for transiting brown dwarfs with NASA's TESS mission
Traditionally, astronomers have separated giant planets from brown dwarfs based on the object's mass. Objects more massive than 13 Jupiter masses but less massive than 80 Jupiter masses are considered to be brown dwarfs. However, in detail, the lower mass threshold is 11 to 16 Jupiter masses depending on the metallicity of the object. This betrays how arbitrary a purely mass-based distinction between planets and brown dwarfs is. Instead, we take a critical look at the population of brown dwarfs for which we have the most fundamental information: transiting brown dwarfs. Transiting brown dwarfs provide us their mass, radius, and sometimes age, which makes them useful for directly testing substellar evolutionary models. Through a better understanding of how well these models describe the population of transiting brown dwarfs, we will develop a better definition of what makes a brown dwarf different from a giant planet: its formation mechanism. It is certainly true that in the mass range spanning between giant planets and low-mass stars that the dominant formation mechanism must change significantly. If we can determine which mass or distribution of masses that this change occurs at, then we will have a more physical way to distinguish planets from brown dwarfs. In this talk, we will review how the TESS mission has contributed to the transiting brown dwarf population so far, and we will examine a few specific examples of transiting brown dwarfs whose masses, radii, and ages have served as useful tests to substellar isochrones.
Host: Snezana Stanimirovic & Melinda Soares-Furtado
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