GeminiFocus 2015 Year in Review | Page 27

is common. The inner ring of DoAr 44 may be replenished by material from the outer disk, accounting for the large water content it maintains compared with similar objects. Alternatively, planets may affect the chemistry in this region where terrestrial planets develop. The warm (450 K) water arises in the inner ring, appearing in emission at mid-infrared wavelengths (Figure 7). The data were obtained at a spectral resolution R ~ 80,000 using the Texas Echelon Cross Echelle Spectrograph (TEXES), a visitor instrument on the Gemini North telescope. Colette Salyk (National Optical Astronomy Observatory and Vassar College) and collaborators used the kinematic characteristics of the spectrally resolved emission to determine the location of its origin, at 0.3 AU. Avoiding destruction of water molecules in this region close to the stellar source requires material in the region — either gas or dust — as protection against the star’s strong radiation. The paper appears in The Astrophysical Journal Letters, volume 810, page L24. The eccentric structure of the emitting disk is consistent with the system being shaped by planets like those in our Solar System, at similar distances from the parent star. Many previously discovered systems have required unusual planets — super-sized Jupiters far from the disk’s center — to create the observed structures. GPI’s excellent resolution and contrast allow probing more distant Sun-like systems than previously possible. GPI provides spectra along with the images, and the results are consistent with a significant water ice component. The complete work has been published in The Astrophysical Journal Letters, volume 807, page L7. July 2015 Continuum-subtracted TEXES spectrum (black) and dominant “hot” model fit (blue), which yields the temperature (450 K) and location (0.3 AU) of the emitting water vapor. A “warm” component (red) is required to account for additional measurements at longer wavelengths. The sum of the models is plotted in gray. Figure 8. This GPI image of HD 115600 in the H band (around 1.6 μm) clearly shows the disk that resembles the Kuiper belt of our own Solar System. The coronagraph blocks the light of the central star (at the position of the cross). The diamond marks the disk’s center. A Solar System Analogue, in Formation Observations using the Gemini Planet Imager (GPI) reveal an analogue of our own Solar System at an early stage of evolution. The debris disk, which resembles the Sun’s “Kuiper belt,” belongs to the young star HD 115600 — a star in the right environment (a massive OB association) to represent the site of the Sun’s formation, with similar mass (1.4 to 1.5 MSun). Thayne Currie (National Astronomical Observatory of Japan) and collaborators have discovered this extrasolar debris disk in direct imaging (Figure 8), and they use the images and spectral information from GPI to determine its properties and possible unseen planets. January 2016 Figure 7. Finding the Outer Edge of Young Stars Near the Galactic Center The very center of the Milky Way Galaxy contains a number of massive stars — despite either the inhospitable environment 2015 Year in Review GeminiFocus 25