Space instrumentation

Abstract:

The Venus Express spacecraft was launched in November 2005. This first European mission to Venus arrived at the planet in April 2006, and within a month had completed on-orbit commissioning and was returning science data to Earth. After four mission extensions and eight years, the spacecraft continues to operate successfully. The end of the mission is anticipated to be in 2014, when the on-board fuel supplies are finally exhausted and the required orbit around Venus can no longer be maintained. This paper discusses the lessons learned by the Venus Express Science Operations Centre (VSOC) over the course of the eight year mission, and briefly discusses the plans for the end of the mission.

Abstract:

We report results of a direct imaging survey for giant planets around 80 members of the Beta Pic, TW Hya, Tucana-Horologium, AB Dor, and Hercules-Lyra moving groups, observed as part of the Gemini NICI Planet-Finding Campaign. For this sample, we obtained median contrasts of \Delta H=13.9 mag at 1" in combined CH4 narrowband ADI+SDI mode and median contrasts of \Delta H=15.1 mag at 2" in H-band ADI mode. We found numerous (>70) candidate companions in our survey images. Some of these candidates were rejected as common-proper motion companions using archival data; we reobserved with NICI all other candidates that lay within 400 AU of the star and were not in dense stellar fields. The vast majority of candidate companions were confirmed as background objects from archival observations and/or dedicated NICI campaign followup. Four co-moving companions of brown dwarf or stellar mass were discovered in this moving group sample: PZ Tel B (36+-6 MJup, 16.4+-1.0 AU, Biller et al. 2010), CD -35 2722B (31+-8 MJup, 67+-4 AU, Wahhaj et al. 2011), HD 12894B (0.46+-0.08 MSun, 15.7+-1.0 AU), and BD+07 1919C (0.20+-0.03 MSun, 12.5+-1.4 AU). From a Bayesian analysis of the achieved H band ADI and ASDI contrasts, using power-law models of planet distributions and hot-start evolutionary models, we restrict the frequency of 1--20 MJup companions at semi-major axes from 10--150 AU to <18% at a 95.4% confidence level using DUSTY models and to <6% at a 95.4% using COND models.

Abstract:

We present integral-field spectroscopy of 27 galaxies in the Coma cluster observed with the Oxford SWIFT spectrograph, exploring the kinematic morphology-density relationship in a cluster environment richer and denser than any in the ATLAS3D survey. Our new data enables comparison of the kinematic morphology relation in three very different clusters (Virgo, Coma and Abell 1689) as well as to the field/group environment. The Coma sample was selected to match the parent luminosity and ellipticity distributions of the early-type population within a radius 15' (0.43 Mpc) of the cluster centre, and is limited to r' = 16 mag (equivalent to M_K = -21.5 mag), sampling one third of that population. From analysis of the lambda-ellipticity diagram, we find 15+-6% of early-type galaxies are slow rotators; this is identical to the fraction found in the field and the average fraction in the Virgo cluster, based on the ATLAS3D data. It is also identical to the average fraction found recently in Abell 1689 by D'Eugenio et al.. Thus it appears that the average slow rotator fraction of early type galaxies remains remarkably constant across many different environments, spanning five orders of magnitude in galaxy number density. However, within each cluster the slow rotators are generally found in regions of higher projected density, possibly as a result of mass segregation by dynamical friction. These results provide firm constraints on the mechanisms that produce early-type galaxies: they must maintain a fixed ratio between the number of fast rotators and slow rotators while also allowing the total early-type fraction to increase in clusters relative to the field. A complete survey of Coma, sampling hundreds rather than tens of galaxies, could probe a more representative volume of Coma and provide significantly stronger constraints, particularly on how the slow rotator fraction varies at larger radii.