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Abstract:

We report the latest Planet Hunter results, including PH2 b, a Jupiter-size (R_PL = 10.12 \pm 0.56 R_E) planet orbiting in the habitable zone of a solar-type star. PH2 b was elevated from candidate status when a series of false positive tests yielded a 99.9% confidence level that transit events detected around the star KIC 12735740 had a planetary origin. Planet Hunter volunteers have also discovered 42 new planet candidates in the Kepler public archive data, of which 33 have at least three transits recorded. Most of these transit candidates have orbital periods longer than 100 days and 20 are potentially located in the habitable zones of their host stars. Nine candidates were detected with only two transit events and the prospective periods are longer than 400 days. The photometric models suggest that these objects have radii that range between Neptune to Jupiter. These detections nearly double the number of gas giant planet candidates orbiting at habitable zone distances. We conducted spectroscopic observations for nine of the brighter targets to improve the stellar parameters and we obtained adaptive optics imaging for four of the stars to search for blended background or foreground stars that could confuse our photometric modeling. We present an iterative analysis method to derive the stellar and planet properties and uncertainties by combining the available spectroscopic parameters, stellar evolution models, and transiting light curve parameters, weighted by the measurement errors. Planet Hunters is a citizen science project that crowd-sources the assessment of NASA Kepler light curves. The discovery of these 43 planet candidates demonstrates the success of citizen scientists at identifying planet candidates, even in longer period orbits with only two or three transit events.

Abstract:

We use multiwavelength (0.12-500 μm) photometry from Herschel-ATLAS, WISE, UKIDSS, SDSS and GALEX to study 23 nearby spheroidal galaxies with prominent dust lanes (DLSGs). DLSGs are considered to be remnants of recent minor mergers, making them ideal laboratories for studying both the interstellar medium (ISM) of spheroids and minor-merger-driven star formation in thenearby Universe. The DLSGs exhibit star formation rates (SFRs) between 0.01and 10M⊙ yr-1 with a median of 0.26M⊙ yr-1 (a factor of 3.5 greater thanthe average SG). The median dust mass, dust-to-stellar mass ratio and dust temperature in these galaxies are around 107.6M⊙, ≈0.05 per cent and ≈19.5K, respectively. The dust masses are at least a factor of 50 greater than that expected from stellar mass loss and, like the SFRs, show no correlationwith galaxy luminosity, suggesting that both the ISM and the star formationhave external drivers. Adopting literature gas-to-dust ratios and star formation histories derived from fits to the panchromatic photometry, we estimate that the median current and initial gasto- stellar mass ratios in these systems are ≈4 and ≈7 per cent, respectively. If, as indicated by recent work, minor mergers that drive star formation in spheroids with (NUV - r) > 3.8 (the colour range of our DLSGs) have stellar mass ratios between 1:6 and 1:10, then the satellite gas fractions are likely =50 per cent. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Abstract:

We present a revised model for the infrared emission of the hyperluminous infrared galaxy IRAS F10214+4724 which takes into account recent photometric data from Spitzer and Herschel that sample the peak of its spectral energy distribution. We first present and discuss a grid of smooth active galactic nucleus (AGN) torus models computed with the method of Efstathiou & Rowan-Robinson and demonstrate that the combination of these models and the starburst models of Efstathiou and coworkers, while able to give an excellent fit to the average spectrum of Seyfert 2s and spectra of individual type 2 quasars measured by Spitzer, fails to match the spectral energy distribution of IRAS F10214+4724. This is mainly due to the fact that the νSν distribution of the galaxy falls very steeply with increasing frequency (a characteristic that is usually indicative of heavy absorption by dust) but shows a silicate feature in emission. Such emission features are not expected in sources with optical/near-infrared type 2 AGN spectral signatures. The Herschel data show that there is more power emitted in the rest-frame 20-50 μm wavelength range compared with the model presented by Efstathiou which assumes three components of emission: an edge-on torus, clouds (at a temperature of 610 and 200 K) that are associated with the narrow-line region (NLR) and a highly obscured starburst that dominates in the submillimetre. We present a revised version of that model that assumes an additional component of emission which we associate with NLR clouds at a temperature of 100 K. The 100 K dust component could also be explained by a highly obscured hot starburst. The model suggests that the NLR of IRAS F10214+4724 has an unusually high covering factor (≥17 per cent) or more likely the magnification of the emission from the NLR clouds is significantly higher than that of the emission from the torus. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Abstract:

The Zooniverse (zooniverse.org) began in 2007 with the launch of Galaxy Zoo, a project in which more than 175,000 people provided shape analyses of more than 1 million galaxy images sourced from the Sloan Digital Sky Survey. These galaxy 'classifications', some 60 million in total, have subsequently been used to produce more than 50 peer-reviewed publications based not only on the original research goals of the project but also because of serendipitous discoveries made by the volunteer community. Based upon the success of Galaxy Zoo the team have gone on to develop more than 25 web-based citizen science projects, all with a strong research focus in a range of subjects from astronomy to zoology where human-based analysis still exceeds that of machine intelligence. Over the past 6 years Zooniverse projects have collected more than 300 million data analyses from over 1 million volunteers providing fantastically rich datasets for not only the individuals working to produce research from their projects but also the machine learning and computer vision research communities. The Zooniverse platform has always been developed to be the 'simplest thing that works', implementing only the most rudimentary algorithms for functionality such as task allocation and user-performance metrics. These simplifications have been necessary to scale the Zooniverse so that the core team of developers and data scientists can remain small and the cost of running the computing infrastructure relatively modest. To date these simplifications have been acceptable for the data volumes and analysis tasks being addressed. This situation however is changing: next generation telescopes such as the Large Synoptic Sky Telescope (LSST) will produce data volumes dwarfing those previously analyzed. If citizen science is to have a part to play in analyzing these next-generation datasets then the Zooniverse will need to evolve into a smarter system capable for example of modeling the abilities of users and the complexities of the data being classified in real time. In this session we will outline the current architecture of the Zooniverse platform and introduce new functionality being developed that should be of interest to the HCOMP community. Our platform is evolving into a system capable of integrating human and machine intelligence in a live environment. Data APIs providing realtime access to 'event streams' from the Zooniverse infrastructure are currently being tested as well as API endpoints for making decisions about for example what piece of data to show next to a volunteer as well as when to retire a piece of data from the live system because a consensus has been reached.

Abstract:

We report on Herschel/PACS observations of absorption lines of OH +, H2O+ and H3O+ in NGC 4418 and Arp 220. Excited lines of OH+ and H2O+ with Elower of at least 285 and ∼200 K, respectively, are detected in both sources, indicating radiative pumping and location in the high radiation density environment of the nuclear regions. Abundance ratios OH +/H2O+ of 1-2.5 are estimated in the nuclei of both sources. The inferred OH+ column and abundance relative to H nuclei are (0.5-1) × 1016 cm-2 and ∼ 2 × 10-8, respectively. Additionally, in Arp 220, an extended low excitation component around the nuclear region is found to have OH +/H2O+ ∼ 5-10. H3O+ is detected in both sources with N(H3O+) ∼ (0.5-2) × 1016 cm-2, and in Arp 220 the pure inversion, metastable lines indicate a high rotational temperature of ∼500 K, indicative of formation pumping and/or hot gas. Simple chemical models favor an ionization sequence dominated by H+ → O+ → OH+ → H2O+ → H3O +, and we also argue that the H+ production is most likely dominated by X-ray/cosmic ray ionization. The full set of observations and models leads us to propose that the molecular ions arise in a relatively low density (≥104 cm-3) interclump medium, in which case the ionization rate per H nucleus (including secondary ionizations) is ζ > 10-13 s-1, a lower limit that is several × 102 times the highest current rate estimates for Galactic regions. In Arp 220, our lower limit for ζ is compatible with estimates for the cosmic ray energy density inferred previously from the supernova rate and synchrotron radio emission, and also with the expected ionization rate produced by X-rays. In NGC 4418, we argue that X-ray ionization due to an active galactic nucleus is responsible for the molecular ion production. © 2013 ESO.