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Red Dwarf Binaries

Our main research recently has been on red dwarf binaries in the solar neighborhood.


So far, we have produced three red dwarf papers. A note is available, and a fourth paper is being prepared.


1. The Observations of Red Dwarf Binaries in the Solar Neighborhood paper was led by Rick Wasson when he had access to the Orange County Astronomers 22" telescope in the De Anza Desert east of Palomar. Techniques for observing faint, relatively close red dwarf binaries were refined during this project. Extending integration times with “quasi-speckle interferometry” (QSI) produced good results. Russ Genet and Dave Rowe participated in this project.


2. The 22" telescope was taken off-line for an upgrade, so observations were switched to the remotely accessed Fairborn Institute Robotic Observatory (FIRO) for further observations. Ivan Altunim (first year undergraduate at UC Berkeley majoring in astrophysics and computer science) joined the team and was first author on the second paper, Red Dwarf Binary Stars in the Solar Neighborhood – II, where we applied the lessons learned in the first paper to another group of systems.


3. We wanted to find a source of previous observations to expand our time base for the observations beyond our current (2021) speckle observations and the archived Gaia 2015 observations. While most past surveys had insufficient resolution to be useful, the United Kingdom IR Telescope (UKIRT) J-band survey had useful resolution. The UKIRT survey was actually looking for very faint young galaxies at the edge of the visible universe. Their light had been shifted from the ultraviolet to the infrared via expansion. The faint red dwarf stars we were interested in were greatly overexposed by the 3.8-m telescope on Mauna Kea, and looked like donuts with the overexposed centers wiped out. But we figured out how to make the measurements in spite of this. As hoped, some of the systems showed some movement over time. Ivan headed up this project and was the first author of the second paper. Sophia Risin (a sophomore at Stanford Online High School) joined the team, as did Simon Dye, a UKIRT astronomer at the University of Nottingham. A paper, Comparison of UKIRT, Gaia, and Speckle Interferometry, has been sent off for publication.


New speckle observations and past Gaia and UKIRT observations have been obtained for eleven known and suspected red dwarf binaries selected for having (potentially) short-period orbits. A note, Equations for Estimating Periods Using Gaia Parameters, provides our period estimation technique. In addition to Gaia and UKIRT, past observations from Pan-STARRS were obtained. Most of these systems are showing clear rotation over the observational period of roughly a decade. A paper is being prepared.

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