The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.
This award will support a twenty-four-month research fellowship by Dr. Jacqueline K. Faherty to work with Dr. Maria T. Ruiz and Dr. Nicole van der Bliek at the University of Chile and with Dr. Andrew West at Boston University in the US.
Star formation studies address questions at the center of modern astrophysics producing results on topics ranging from the planetary frequency in the Galaxy to the conditions of the primordial Universe under which the first stars were born. The most abundant stars in the Galaxy are the lowest-temperature M dwarfs therefore they are a key to understanding how chemical, environmental and/or spatial conditions affect the processes of star formation. Astronomers have long studied regions such as Orion, Ophiucus, Taurus etc, in great detail and our knowledge of many physical characteristics of star formation come from studies of these dense and highly active areas on the sky. Unfortunately, the distances to these star-forming regions make detailed studies--directly detecting and resolving disks, looking for low-mass companions--of the intrinsically faint M dwarfs, difficult.
The most promising M dwarf targets for current and future star and planetary formation studies will be found in the recently identified juvenile aged (8-50 Myr), close (<100pc), co-moving collections of stars called moving groups. The youthfulness of moving groups makes them appealing targets for searching for circumstellar and/or accretion disks and the proximity to the Sun makes them easy targets for imaging and spectroscopy to resolve disk structure and companions. The objective of the proposed research is to take advantage of a unique kinematic dataset of M dwarfs, and investigate potential new members of intermediate-aged moving groups in the local vicinity of the Sun. These new members fill large gaps in our understanding of the processes of planetary and stellar development.
BACKGROUND--Brown dwarfs are one of the most recent and exciting additions to the list of objects studied in Astronomy. Their importance is drawn from their abundance in the Milky Way, their ability to constrain star and planet formation models, and their spectral and photometric similarity to giant exoplanets. The primary objective of this NSF IRFP grant was to identify the population of juvenile age (10 - 150 Myr) brown dwarfs belonging to nearby collections of co-moving stars. Ages of brown dwarfs are notoriously difficult to pinpoint because they have no sustained nuclear burning. Instead they cool for the majority of their lives passing through similar observational stages at very different ages. A juvenile age population of brown dwarfs becomes THE benchmark for breaking the degeneracy between ages, masses and observable properties of the population. Most importantly, juvenile age brown dwarfs strongly resemble giant exoplanets therefore they can be used as a template for understanding physical properties of planetary systems. Drawing from my expertise in studying the motions of low temperature objects, I was able to investigate the kinematics of sources (both known and novel) and assign them to nearby moving groups. SCIENCE OUTCOME HIGHLIGHTS---One of the most exciting science outcomes of this NSF IRFP grant came from the discovery of a population of low-temperature juvenile age brown dwarfs. Many of these were known and suspected to be young given their unusual spectral and photometric features. However, not until the distances and velocities were obtained (many of which during this NSF IRFP tenure) were we able to definitively place them in age-calibrated moving groups. I published the 150 Myr, 13-30 Jupiter mass source 2M0355 in Faherty et al. 2013 and it has since become an exemplary source for comparative brown dwarf/exoplanet studies (see Figure 1). I am currently preparing another 63 objects for publication in a large compilation (Faherty et al. in prep). As discussed in Faherty et al. 2013b, these sources are excellent analogs and in some cases equivalents to the directly imaged giant exoplanets. The majority are in Beta Pictoris (20 Myr), Tucana Horologium (30 Myr), or Columba (30 Myr) where we also find 5 - 10 Jupiter mass planetary mass companions. As such we can directly compare observable data on individual objects to detangle age, weather, and temperature effects. Importantly, since my sample is bright and isolated, it is vastly easier for me to obtain data on sources so these young brown dwarfs are anchors to our understanding of current and future (from GPI, SPHERE, Project 1640, JWST, etc) exoplanet data sets. The dataset collected and analyzed during this NSF IRFP tenure is critical to multiple subfields (both brown dwarf and planetary alike). OUTREACH ENDEAVORS--As part of the education component to this NSF IRFP grant, I designed and executed an outreach project on Easter Island for the June 5th/6th transit of Venus, consisting of museum workshops, public talks, school visits (all in Spanish) and a transit viewing event that reached over 2500 residents (nearly 50% of the island--see www.flickr.com/photos/jfaherty/sets/72157630029839847/ for picture summary and Figure 2). I also organized a global network of school groups from differing political, economic, and racial backgrounds to measure Venus-Sun contact times leading to a solar distance measurement (see Faherty et al. 2012b). This project was high impact ereaching students from 10 countries on 6 different continents.
