Klaus W. Hodapp

Discovery of the Coldest Imaged Companion of a Sun-like Star

We present the discovery of a brown dwarf or possible planet at a projected separation of 19 = 29 AU around the star GJ 758, placing it between the separations at which substellar companions are expected to form by core accretion (~5 AU) or direct gravitational collapse (typically 100 AU). The object was detected by direct imaging of its thermal glow with Subaru/HiCIAO. At 10-40 times the mass of Jupiter and a temperature of 550-640 K, GJ 758 B constitutes one of the few known T-type companions, and the coldest ever to be imaged in thermal light around a Sun-like star. Its orbit is likely eccentric and of a size comparable to Plutos orbit, possibly as a result of gravitational scattering or outward migration. A candidate second companion is detected at 12 at one epoch.

Images of the Extended Outer Regions of the Debris Ring Around HR 4796 A

We present high-contrast images of HR 4796 A taken with Subaru/HiCIAO in the H band, resolving the debris disk in scattered light. The application of specialized angular differential imaging methods allows us to trace the inner edge of the disk with high precision and reveals a pair of streamers extending radially outward from the ansae. Using a simple disk model with a power-law surface brightness profile, we demonstrate that the observed streamers can be understood as part of the smoothly tapered outer boundary of the debris disk, which is most visible at the ansae. Our observations are consistent with the expected result of a narrow planetesimal ring being ground up in a collisional cascade, yielding dust with a wide range of grain sizes. Radiation forces leave large grains in the ring and push smaller grains onto elliptical or even hyperbolic trajectories. We measure and characterize the disks surface brightness profile, and confirm the previously suspected offset of the disks center from the stars position along the rings major axis. Furthermore, we present first evidence for an offset along the minor axis. Such offsets are commonly viewed as signposts for the presence of unseen planets within a disks cavity. Our images also offer new constraints on the presence of companions down to the planetary mass regime (~9 M Jup at 05, ~3 M Jup at 1).

THE MOVING GROUP TARGETS OF THE SEEDS HIGH-CONTRAST IMAGING SURVEY OF EXOPLANETS AND DISKS: RESULTS AND OBSERVATIONS FROM THE FIRST THREE YEARS

We present results from the first three years of observations of moving group (MG) targets in the Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS) high-contrast imaging survey of exoplanets and disks using the Subaru telescope. We achieve typical contrasts of ~105 at 1 and ~106 beyond 2 around 63 proposed members of nearby kinematic MGs. We review each of the kinematic associations to which our targets belong, concluding that five, β Pictoris (~20 Myr), AB Doradus (~100 Myr), Columba (~30 Myr), Tucana-Horogium (~30 Myr), and TW Hydrae (~10 Myr), are sufficiently well-defined to constrain the ages of individual targets. Somewhat less than half of our targets are high-probability members of one of these MGs. For all of our targets, we combine proposed MG membership with other age indicators where available, including Ca II HK emission, X-ray activity, and rotation period, to produce a posterior probability distribution of age. SEEDS observations discovered a substellar companion to one of our targets, κ And, a late B star. We do not detect any other substellar companions, but do find seven new close binary systems, of which one still needs to be confirmed. A detailed analysis of the statistics of this sample, and of the companion mass constraints given our age probability distributions and exoplanet cooling models, will be presented in a forthcoming paper.

Infrared Doppler instrument for the Subaru Telescope (IRD)

Because of their large numbers, red dwarfs may be the most abundant planet hosts in our Galaxy. In order to detect Earth-like planets around nearby red dwarfs (in particular late-M stars), it is crucial to conduct the precise radial velocity (RV) measurements at near-infrared wavelengths where these stars emit most of light. We report the development of the Infrared Doppler (IRD) spectrometer for the Subaru telescope. IRD is a fiber-fed, high-precision, near infrared spectrometer with a spectral resolution of R~70,000 covering from 0.97 to 1.75 μm. To achieve 1m/s RV measurement precision, we employ our original laser frequency comb of a wide-wavelength coverage as an extremely stable wavelength standard in the near-infrared. The spectrometer optics is composed of a new wide-pitch Echelle-grating and Volume-Phase Holographic gratings. To achieve ultimate thermal stability, very low thermal expansion ceramic is used for most of the optical components including the optical bench. The spectrometer will utilize a 4096×4096-pixel HgCdTe array.

Daytime GEO Satellite Characterization with the HANDS- IONS Camera

Daytime imaging of GEO satellites is challenging due to the bright background of the daytime sky. However, with the appropriate selection of wavelengths, we show that it is possible to detect GEO satellites in the infrared. The design of the purpose-built camera system for detecting GEO satellites is discussed, along with the anticipated performance of the system.

IMAKA: imaging from Mauna KeA with an atmosphere corrected 1 square degree optical imager

The goal of this project is to achieve exquisite image quality over the largest possible field of view, with a goal of a FWHM of not more than 0.3 over a square degree field in the optical domain. The narrow PSF will allow detection of fainter sources in reasonable exposure times. The characteristics of the turbulence of Mauna Kea, a very thin ground layer with excellent free seeing allows very wide fields to be corrected by GLAO and would make such an instrument unique. The Ground Layer AO module uses a deformable mirror conjugated to the telescope pupil. Coupled with a high order WFS, it corrects the turbulence common to the entire field. Over such large fields the probability of finding sufficiently numerous and bright natural guide sources is high, but a constellation of laser beacons could be considered to ensure homogeneous and uniform image quality. The free atmosphere seeing then limits the image quality (50% best conditions: 0.2 to 0.4). This can be further improved by an OTCCD camera, which can correct local image motion on isokinetic scales from residual high altitude tip-tilt. The advantages of the OTCCD are not limited to improving the image quality: a Panstarrs1 clone covers one square degree with 0.1 sampling, in perfect accordance with the scientific requirements. The fast read time (6 seconds for 1.4 Gpixels) also leads to an improvement of the dynamic range of the images. Finally, the guiding capabilities of the OTCCD will provide the overall (local and global) tip-tilt signal.

UKIRT under new management: status and plans

The United Kingdom Infrared Telescope (UKIRT) observatory has been transferred to the ownership of the University of Hawaii (UH) and is now being managed by UH. We have established partnerships with several organizations to utilize the UKIRT for science projects and to support its operation. Our main partners are the U.S. Naval Observatory (USNO), the East Asian Observatory (EAO), and the UKIRT microlensing team (JPL/IPAC/OSU/Vanderbilt). The USNO is working on deep northern hemisphere surveys in the H and K bands and the UKIRT microlensing team is running a monitoring campaign of the Galactic bulge. EAO, UH, and USNO have individual P.I. research programs. Most of the observations are using the Wide Field Camera (WFCAM), but the older suite of cassegrain instruments are still fully operational. Data processing and archiving continue to be done CASU and WSA in the UK. We are working on a concept to upgrade the WFCAM with new larger infrared detector arrays for substantially improved survey efficiency.

NUMERICAL SIMULATION of the SVS 13 MICROJET and BOW SHOCK BUBBLE

Numerical simulations of the SVS 13 microjet and bow shock bubble are performed using the WENO method that reproduces the main features and dynamics of data from the Keck Telescope/OSIRIS velocity-resolved integral field spectrograph: an expanding, cooler bow shock bubble, with the bubble center moving at approximately 50 km s−1 with a radial expansion velocity of 11 km s−1, surrounding the fast, hotter jet, which is propagating at 156 km s−1. Contact and bow shock waves are visible in the simulations both from the initial short jet pulse that creates the nearly spherical bow shock bubble and from the fast microjet, while a terminal Mach disk shock is visible near the tip of the continuous microjet, which reduces the velocity of the jet gas down to the flow velocity of the contact discontinuity at the leading edge of the jet. At 21.1 years after the launch of the initial bubble pulse, the jet has caught up with and penetrated almost all the way across the bow shock bubble of the slower initial pulse. At times later than about 22 years, the jet has penetrated through the bubble and thereafter begins to subsume its spherical form. Emission maps from the simulations of the jet—traced by the emission of the shock-excited 1.644 μm [Fe ii] line—and the bow shock bubble—traced in the lower excitation 2.122 μm H2 1–0 S(1) line—projected onto the plane of the sky are presented, and are in good agreement with the Keck observations.