How often do M-dwarf stars have companions?

M-dwarfs make up the majority (>70%) of the solar neighborhood, but there is much to learn about their population statistics, particularly in terms of binary formation and dynamical evolution.

The M-dwarfs in Multiples (MinMs) Survey is a large, volume-limited sample of 245 of these small, cool stars to detect and characterize their stellar and brown dwarf companions.

Using adaptive optics imaging from facilities like the MMT, VLT, CFHT, and Subaru, and archival wide-field imaging, we have found that M-dwarf stellar binaries are less frequently found in comparison to higher-mass stars, but these systems tend to be at much closer orbital separations.

MinMs I:
Stellar companions to M-dwarfs within 15 pc (KWD et al. 2015; ADS link)
MinMs II:
Substellar companions to M-dwarfs within 15 pc (KWD et al. 2019b, in prep)

What are the formation environments of young low-mass dwarfs?

As part of the Taurus Boundary of Stellar/Substellar TBOSS Survey collaboration, I have used the Atacama Large Millimeter/Submillimeter Array (ALMA) to measure the dust content of protoplanetary disks around the lowest-mass stars and brown dwarfs in the Taurus star-forming region.

What can we learn from spectroscopy of substellar objects?

GPI Characterization:
Substellar companions occupy unusual regions in color-magnitude space that suggest that their atmospheres may be substantially different from similar temperature objects in the field population. I have worked on the near-infrared spectral characterization of substellar companions with the Gemini Planet Imager (GPI) and MMT ARIES instruments.


⚬ Characterizing the unusually red companion to HD 206893 (KWD et al. 2019a, in prep)

Substellar Transition Disks:
I also use moderate-resolution spectroscopy with facilities like X-shooter, SpeX, and iSHELL to measure the properties of transitional disks around the lowest-mass stars and brown dwarfs. By combining multiwavelength observations and searching for signatures of accretion and binarity, we can start to explore the planet-forming potential of disks around the lowest-mass stellar and substellar systems.

⚬ Accretion, winds, and rotation in V410 X-ray 6 (Komarova and KWD et al. 2019, in prep)*

*Undergraduate student-led publication; see Mentoring page

Direct imaging of exoplanets and substellar companions

I am very excited about the future of high-contrast imaging and current and upcoming efforts to directly image planetary companions. As a member of the Gemini Planet Imager Exoplanet Survey (GPIES) team, I have worked on GPI calibration and observing efforts as well as target sample parameters for the survey, which is currently being completed as of 2019.

I have been involved with additional direct imaging surveys as a member of the Large Binocular Telescope Exoplanet-Exozodi Common Hunt program (survey results), and have worked closely with the Magellan/MagAO team to support their observing campaigns. I am also leading programs to search for and characterize substellar companions with both MagAO and VLT/NaCo.

Previous Projects and Experience

Protoplanetary Disks and High-Contrast Imaging

With an NSF Graduate Opportunities Worldwide (GROW) fellowship, and as part of the TBOSS project, I worked at the Universidad de Chile with Dr. François Ménard and Dr. Gerrit van der Plas on ALMA studies of protoplanetary disk properties in Taurus and Upper Scorpius. As part of the GPI Exoplanet Survey campaign, my NSF GROW fellowship also included work on GPI and Magellan/VisAO imaging at Universidad de Chile with Dr. Patricio Rojo.

Relevant publications:
Dust Masses of Disks around 8 Brown Dwarfs and Very Low-mass Stars in Upper Sco OB1 and Ophiuchus (van der Plas, Ménard, KWD et al. 2016; ADS link)

High-Mass Stellar Multiplicity

The technique of optical interferometry provides the angular resolution needed to measure close binary companions to massive stars. As part of the 2014 NSF East Asia and Pacific Summer Institutes program, I worked with Dr. Mike Ireland at Australian National University to measure nearby B-stars with the Sydney University Stellar Interferometer (SUSI).