Publication archive

Publication archive

The European Space Agency's Planck satellite, dedicated to studying the early Universe and its subsequent evolution, was launched 14 May 2009 and has been scanning the microwave and submillimetre sky continuously since 12 August 2009. In March 2013, ESA and the Planck Collaboration released the initial cosmology products based on the first 15.5 months of Planck data, along with a set of scientific and technical papers and a web-based explanatory supplement. This paper gives an overview of the mission and its performance, the processing, analysis, and characteristics of the data, the scientific results, and the science data products and papers in the release. The science products include maps of the cosmic microwave background (CMB) and diffuse extragalactic foregrounds, a catalogue of compact Galactic and extragalactic sources, and a list of sources detected through the Sunyaev-Zeldovich effect. The likelihood code used to assess cosmological models against the Planck data and a lensing likelihood are described. Scientific results include robust support for the standard six-parameter ΛCDM model of cosmology and improved measurements of its parameters, including a highly significant deviation from scale invariance of the primordial power spectrum. The Planck values for these parameters and others derived from them are significantly different from those previously determined. Several large-scale anomalies in the temperature distribution of the CMB, first detected by WMAP, are confirmed with higher confidence. Planck sets new limits on the number and mass of neutrinos, and has measured gravitational lensing of CMB anisotropies at greater than 25σ. Planck finds no evidence for non-Gaussianity in the CMB. Planck's results agree well with results from the measurements of baryon acoustic oscillations. Planck finds a lower Hubble constant than found in some more local measures.
--- Remainder of abstract truncated due to character limitations ---
Published: 29 October 2014
Press kit for the 12 November 2014 press event marking the landing of Rosetta's lander Philae on comet 67P/Churyumov-Gerasimenko.

Contents:
Media services
Mission facts
Highlights
Selecting a landing site
Landing on a comet
Comets – an introduction
Rosetta's comet
Missions to comets
Appendix A: Provisional programme for press event at ESOC
Appendix B: Selected images and videos
Appendix C: Distances, dates, times for mission
Appendix D: Timeline for separation

Errata

pg 48: a minus sign is missing from the temperature quoted. The text should read: "The average surface temperature, reported by the VIRTIS team, is -70 °C (205 K)"
Published: 05 November 2014
The European Space Agency's Rosetta spacecraft flew by asteroid (21) Lutetia on July 10, 2010. Observations through the OSIRIS camera have revealed many geological features. Lineaments are identified on the entire observed surface of the asteroid. Many of these features are concentric around the North Pole Crater Cluster (NPCC). As observed on (433) Eros and (4) Vesta, this analysis of Lutetia assesses whether or not some of the lineaments could be created orthogonally to observed impact craters. The results indicate that the orientation of lineaments on Lutetia's surface could be explained by three impact craters: the Massilia and the NPCC craters observed in the northern hemisphere, and candidate crater Suspicio inferred to be in the southern hemisphere. The latter has not been observed during the Rosetta flyby. Of note, is that the inferred location of the Suspicio impact crater derived from lineaments matches locations where hydrated minerals have been detected from Earth-based observations in the southern hemisphere of Lutetia. Although the presence of these minerals has to be confirmed, this analysis shows that the topography may also have a significant contribution in the modification of the spectral shape and its interpretation. The cross-cutting relationships of craters with lineaments, or between lineaments themselves show that Massilia is the oldest of the three impact feature, the NPCC the youngest, and that the Suspicio impact crater is of intermediate age that is likely occurred closer in time to the Massilia event.
Published: 16 October 2014

Press kit updated in October for Go for landing on the primary landing site.

Contents:
Media services
Quick reference mission facts
Highlights from the Rosetta mission thus far
Selecting Site J, a landing site for Philae
Landing on a Comet
Comets – an introduction
Rosetta's comet – at a glance
Missions to comets - Rosetta in context
Appendix A: Distances, dates, times for mission milestones

Published: 13 October 2014
Published online 9 October 2014, in Science Express

Exoplanets that orbit close to their host stars are much more highly irradiated than their Solar System counterparts. Understanding the thermal structures and appearances of these planets requires investigating how their atmospheres respond to such extreme stellar forcing. We present spectroscopic thermal emission measurements as a function of orbital phase ("phase-curve observations") for the highly-irradiated exoplanet WASP-43b spanning three full planet rotations using the Hubble Space Telescope. With these data, we construct a map of the planet's atmospheric thermal structure, from which we find large day-night temperature variations at all measured altitudes and a monotonically decreasing temperature with pressure at all longitudes. We also derive a Bond albedo of 0.18+0.07-0.12and an altitude dependence in the hot-spot offset relative to the substellar point.

Published: 10 October 2014
Titan's middle atmosphere is currently experiencing a rapid change of season after northern spring arrived in 2009 (refs 1, 2). A large cloud was observed for the first time above Titan's southern pole in May 2012, at an altitude of 300 kilometres. A temperature maximum was previously observed there, and condensation was not expected for any of Titan's atmospheric gases. Here we report that this cloud is composed of micrometre-sized particles of frozen hydrogen cyanide (HCN ice). The presence of HCN particles at this altitude, together with temperature determinations from mid-infrared observations, indicate a dramatic cooling of Titan's atmosphere inside the winter polar vortex in early 2012. Such cooling is in contrast to previously measured high-altitude warming in the polar vortex, and temperatures are a hundred degrees colder than predicted by circulation models. These results show that post-equinox cooling at the winter pole of Titan is much more efficient than previously thought.
Published: 03 October 2014
Reference: ESA/SRE(2014)1

This report, the so-called Red Book, provides a scientific, technical and management summary of the JUICE definition study that was performed from February 2012 to October 2014.

The JUICE (JUpiter ICy moons Explorer) mission has been selected by ESA in May 2012 to be the first large mission within the Cosmic Vision Program 2015-2025.

Published: 01 October 2014
Transmission spectroscopy has so far detected atomic and molecular absorption in Jupiter-sized exoplanets, but intense efforts to measure molecular absorption in the atmospheres of smaller (Neptune-sized) planets during transits have revealed only featureless spectra. From this it was concluded that the majority of small, warm planets evolve to sustain atmospheres with high mean molecular weights (little hydrogen), opaque clouds or scattering hazes, reducing our ability to observe the composition of these atmospheres. Here we report observations of the transmission spectrum of the exoplanet HAT-P-11b (which has a radius about four times that of Earth) from the optical wavelength range to the infrared. We detected water vapour absorption at a wavelength of 1.4 micrometres. The amplitude of the water absorption (approximately 250 parts per million) indicates that the planetary atmosphere is predominantly clear down to an altitude corresponding to about 1 millibar, and sufficiently rich in hydrogen to have a large scale height (over which the atmospheric pressure varies by a factor of e). The spectrum is indicative of a planetary atmosphere in which the abundance of heavy elements is no greater than about 700 times the solar value. This is in good agreement with the core-accretion theory of planet formation, in which a gas giant planet acquires its atmosphere by accreting hydrogen-rich gas directly from the protoplanetary nebula onto a large rocky or icy core.
Published: 25 September 2014
Published online: 17 September 2014

Ultra-compact dwarf galaxies are among the densest stellar systems in the Universe. These systems have masses of up to 2 × 108 solar masses, but half-light radii of just 3-50 parsecs. Dynamical mass estimates show that many such dwarfs are more massive than expected from their luminosity. It remains unclear whether these high dynamical mass estimates arise because of the presence of supermassive black holes or result from a non-standard stellar initial mass function that causes the average stellar mass to be higher than expected. Here we report adaptive optics kinematic data of the ultra-compact dwarf galaxy M60-UCD1 that show a central velocity dispersion peak exceeding 100 kilometres per second and modest rotation. Dynamical modelling of these data reveals the presence of a supermassive black hole with a mass of 2.1 × 107 solar masses. This is 15 per cent of the object's total mass. The high black hole mass and mass fraction suggest that M60-UCD1 is the stripped nucleus of a galaxy. Our analysis also shows that M60-UCD1's stellar mass is consistent with its luminosity, implying a large population of previously unrecognized supermassive black holes in other ultra-compact dwarf galaxies.

Published: 19 September 2014
The water abundance in a planetary atmosphere provides a key constraint on the planet's primordial origins because water ice is expected to play an important role in the core accretion model of planet formation. However, the water content of the solar system giant planets is not well known because water is sequestered in clouds deep in their atmospheres. By contrast, short-period exoplanets have such high temperatures that their atmospheres have water in the gas phase, making it possible to measure the water abundance for these objects. We present a precise determination of the water abundance in the atmosphere of the 2 MJup short-period exoplanet WASP-43b based on thermal emission and transmission spectroscopy measurements obtained with the Hubble Space Telescope. We find the water content is consistent with the value expected in a solar composition gas at planetary temperatures (0.4-3.5 × solar at 1σ confidence). The metallicity of WASP-43b's atmosphere suggested by this result extends the trend observed in the solar system of lower metal enrichment for higher planet masses.
Published: 13 September 2014
Published online: 12 September 2014

Aims. Approach observations with the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) experiment onboard Rosetta are used to determine the rotation period, the direction of the spin axis, and the state of rotation of comet 67P's nucleus.

Methods. Photometric time series of 67P have been acquired by OSIRIS since the post wake-up commissioning of the payload in March 2014. Fourier analysis and convex shape inversion methods have been applied to the Rosetta data as well to the available ground-based observations.

Results. Evidence is found that the rotation rate of 67P has significantly changed near the time of its 2009 perihelion passage, probably due to sublimation-induced torque. We find that the sidereal rotation periods P1 = 12.76129 ± 0.00005 h and P2 = 12.4043 ± 0.0007 h for the apparitions before and after the 2009 perihelion, respectively, provide the best fit to the observations. No signs of multiple periodicity are found in the light curves down to the noise level, which implies that the comet is presently in a simple rotation state around its axis of largest moment of inertia. We derive a prograde rotation model with spin vector J2000 ecliptic coordinates λ = 65° ± 15°, β = + 59° ± 15°, corresponding to equatorial coordinates RA = 22°, Dec = + 76°. However, we find that the mirror solution, also prograde, at λ = 275° ± 15°, β = + 50° ± 15° (or RA = 274°, Dec = + 27°), is also possible at the same confidence level, due to the intrinsic ambiguity of the photometric problem for observations performed close to the ecliptic plane.

Published: 13 September 2014
Unedited accepted article published online 11 September 2014.
Final edit of article will appear later.

On September 26th, 2005, Cassini conducted its only close targeted flyby of Saturn's small, irregularly shaped moon Hyperion. Approximately 6 minutes before the closest approach, the Electron spectrometer (ELS), part of the Cassini Plasma Spectrometer (CAPS) detected a field-aligned electron population originating from the direction of the moon's surface. Plasma wave activity detected by the Radio and Plasma Wave (RPWS) instrument suggests electron beam activity. A dropout in energetic electrons was observed by both CAPS-ELS and the Magnetospheric Imaging Instrument Low Energy Magnetospheric Measurement System (MIMI-LEMMS), indicating that the moon and the spacecraft were magnetically connected when the field-aligned electron population was observed. We show that this constitutes a remote detection of a strongly negative (~ -200 V) surface potential on Hyperion, consistent with the predicted surface potential in regions near the solar terminator.

Published: 12 September 2014
Reference: SPC(2013)33 The CHaracterising ExOPlanet Satellite (CHEOPS) is a Small mission in the ESA Science Programme to be implemented in partnership with Switzerland, and with a number of Member States delivering significant contributions. These Member States are Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Sweden, and UK, and will cooperate under a Swiss led CHEOPS Mission Consortium (CMC). The Science Management Plan (SMP) defines the top-level science management principles and organisation of the mission. It identifies roles and duties of ESA, the CMC, and the scientific community at large. The document provides an overview of the mission science objectives and a high-level description of the operations and processes that will be established to generate the outlined scientific data products. The SMP addresses the data rights policy, and the distribution of responsibilities for public outreach and communication.
Published: 25 October 2013
The deflection angles of lensed sources increase with their distance behind a given lens. We utilize this geometric effect to corroborate the zphot ≃ 9.8 photometric redshift estimate of a faint near-IR dropout, triply imaged by the massive galaxy cluster A2744 in deep Hubble Frontier Fields images. The multiple images of this source follow the same symmetry as other nearby sets of multiple images that bracket the critical curves and have well-defined redshifts (up to zspec ≃ 3.6), but with larger deflection angles, indicating that this source must lie at a higher redshift. Similarly, our different parametric and non-parametric lens models all require this object be at z ≳ 4, with at least 95% confidence, thoroughly excluding the possibility of lower-redshift interlopers. To study the properties of this source, we correct the two brighter images for their magnifications, leading to a star formation rate of ~0.3 M yr-1, a stellar mass of ~4 × 107 M, and an age of ≲ 220 Myr (95% confidence). The intrinsic apparent magnitude is 29.9 AB (F160W), and the rest-frame UV (~1500 Å) absolute magnitude is MUV, AB = -17.6. This corresponds to ~ 0.1 L*z=8 (~0.2 L*z=10, adopting dM*/dz ~ 0.45), making this candidate one of the least luminous galaxies discovered at z ~ 10.
Published: 05 September 2014
Hundreds of lakes and a few seas of liquid hydrocarbons have been observed by the Cassini spacecraft to cover the polar regions of Titan. A significant fraction of these lakes or seas could possibly be interconnected with subsurface liquid reservoirs of alkanes. In this paper, we investigate the interplay that would happen between a reservoir of liquid hydrocarbons located in Titan's subsurface and a hypothetical clathrate reservoir that progressively forms if the liquid mixture diffuses throughout a preexisting porous icy layer. To do so, we use a statistical-thermodynamic model in order to compute the composition of the clathrate reservoir that forms as a result of the progressive entrapping of the liquid mixture. This study shows that clathrate formation strongly fractionates the molecules between the liquid and the solid phases. Depending on whether the structures I or II clathrate forms, the present model predicts that the liquid reservoirs would be mainly composed of either propane or ethane, respectively. The other molecules present in the liquid are trapped in clathrates. Any river or lake emanating from subsurface liquid reservoirs that significantly interacted with clathrate reservoirs should present such composition. On the other hand, lakes and rivers sourced by precipitation should contain higher fractions of methane and nitrogen, as well as minor traces of argon and carbon monoxide.
Published: 02 August 2014
A type Ia supernova is thought to be a thermonuclear explosion of either a single carbon-oxygen white dwarf or a pair of merging white dwarfs. The explosion fuses a large amount of radioactive 56Ni (refs 1-3). After the explosion, the decay chain from 56Ni to 56Co to 56Fe generates γ-ray photons, which are reprocessed in the expanding ejecta and give rise to powerful optical emission. Here we report the detection of 56Co lines at energies of 847 and 1,238 kiloelectronvolts and a γ-ray continuum in the 200-400 kiloelectronvolt band from the type Ia supernova 2014J in the nearby galaxy M82. The line fluxes suggest that about 0.6 ± 0.1 solar masses of radioactive 56Ni were synthesized during the explosion. The line broadening gives a characteristic mass-weighted ejecta expansion velocity of 10,000 ± 3,000 kilometres per second. The observed γ-ray properties are in broad agreement with the canonical model of an explosion of a white dwarf just massive enough to be unstable to gravitational collapse, but do not exclude merger scenarios that fuse comparable amounts of 56Ni.
Published: 29 August 2014
On 21 January 2005, a moderate magnetic storm produced a number of anomalous features, some seen more typically during superstorms. The aim of this study is to establish the differences in the space environment from what we expect (and normally observe) for a storm of this intensity, which make it behave in some ways like a superstorm. The storm was driven by one of the fastest interplanetary coronal mass ejections in solar cycle 23, containing a piece of the dense erupting solar filament material. The momentum of the massive solar filament caused it to push its way through the flux rope as the interplanetary coronal mass ejection decelerated moving toward 1 AU creating the appearance of an eroded flux rope (see companion paper by Manchester et al. (2014)) and, in this case, limiting the intensity of the resulting geomagnetic storm. On impact, the solar filament further disrupted the partial ring current shielding in existence at the time, creating a brief superfountain in the equatorial ionosphere - an unusual occurrence for a moderate storm. Within 1 h after impact, a cold dense plasma sheet (CDPS) formed out of the filament material. As the interplanetary magnetic field (IMF) rotated from obliquely to more purely northward, the magnetotail transformed from an open to a closed configuration and the CDPS evolved from warmer to cooler temperatures. Plasma sheet densities reached tens per cubic centimeter along the flanks - high enough to inflate the magnetotail in the simulation under northward IMF conditions despite the cool temperatures. Observational evidence for this stretching was provided by a corresponding expansion and intensification of both the auroral oval and ring current precipitation zones linked to magnetotail stretching by field line curvature scattering.
[Remainder of abstract truncated due to character limitations]
Published: 29 August 2014
Type-Ia supernovae result from binary systems that include a carbon-oxygen white dwarf, and these thermonuclear explosions typically produce 0.5 MSun of radioactive 56Ni. The 56Ni is commonly believed to be buried deeply in the expanding supernova cloud. Surprisingly, in SN2014J we detected the lines at 158 and 812 keV from 56Ni decay (τ~8.8 days) earlier than the expected several-week time scale, only ~20 days after the explosion, and with flux levels corresponding to roughly 10% of the total expected amount of 56Ni. Some mechanism must break the spherical symmetry of the supernova, and at the same time create a major amount of 56Ni at the outskirts. A plausible explanation is that a belt of helium from the companion star is accreted by the white dwarf, where this material explodes and then triggers the supernova event.
Published: 01 August 2014

Press kit for the 6 August 2014 press event marking the arrival of Rosetta at comet 67P/Churyumov-Gerasimenko. Contents:
Media services
Rosetta arrives at comet 67P/ Churyumov-Gerasimenko
Quick reference mission facts
Highlights from the Rosetta mission thus far
How Rosetta arrives at and orbits comet 67P/C-G
Selecting a Landing Site for Rosetta’s lander, Philae
Landing on a Comet
Comets – an introduction
Rosetta's comet – at a glance
Missions to comets - Rosetta in context
Appendix A: Draft programme for press event
Appendix B: Speakers at the 6 August press event
Appendix C: Selected Rosetta images & videos
Appendix D: Mission timeline for August to November
Appendix E: Distances, dates, times for mission milestones

An earlier version of the press kit contained an error on page 12: the paragraph on the provision of the lander should read: Rosetta's Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI.

Published: 05 August 2014

Rosetta is ESA's comet-chasing mission to 67P/Churyumov-Gerasimenko. Launched on 2 March 2004, the spacecraft travelled for 10 years and required three gravity-assist flybys at Earth and one at Mars before homing in on its target.

Comets are considered to be the most primitive building blocks of our cosmic neighbourhood, surviving the Solar System's chaotic 4.6 billion-year history more or less intact. Laced with ice and organic materials, comets likely helped to 'seed' Earth with water, and perhaps even the ingredients for life. By studying one of these icy treasure chests in great detail, ESA's Rosetta is set to unlock the secrets of the Solar System.

Table of contents:

  • Rosetta: Europe's comet-chaser
  • The long trek
  • Fleeting flybys of battered worlds
  • Hot and cold
  • What do we know about comet 67P/Churyumov-Gerasimenko?
  • Rendezvous with a comet
  • Landing on a comet
  • The Rosetta orbiter
  • The Philae lander
  • Escorting a comet
  • Long-distance communications
  • An international enterprise
  • Join the adventure

Note: a more recent Rosetta mission brochure (ESA BR-321) is available here.

Published: 23 July 2014
22-Nov-2019 08:25 UT

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