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Georgina Dransfield, Amaury H M J Triaud, Tristan Guillot, Djamel Mekarnia, David Nesvorný, Nicolas Crouzet, Lyu Abe, Karim Agabi, Marco Buttu, Juan Cabrera, Davide Gandolfi, Maximilian N Günther, Florian Rodler, François-Xavier Schmider, Philippe Stee, Olga Suarez, Karen A Collins, Martín Dévora-Pajares, Steve B Howell, Elisabeth C Matthews, Matthew R Standing, Keivan G Stassun, Chris Stockdale, Samuel N Quinn, Carl Ziegler, Ian J M Crossfield, Jack J Lissauer, Andrew W Mann, Rachel Matson, Joshua Schlieder, George Zhou |
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Title |
HD 28109 hosts a trio of transiting Neptunian planets including a near-resonant pair, confirmed by ASTEP from Antarctica |
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Journal |
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Year |
2022 |
Publication |
Monthly Notices of the Royal Astronomical Society |
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Volume |
515 |
Issue |
1 |
Pages |
1328-1345 |
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Abstract  |
We report on the discovery and characterization of three planets orbiting the F8 star HD 28109, which sits comfortably in ${TESS}$’s continuous viewing zone. The two outer planets have periods of $\rm 56.0067 \pm 0.0003~d$ and $\rm 84.2597{-0.0008}^{+0.0010}~d$, which implies a period ratio very close to that of the first-order 3:2 mean motion resonance, exciting transit timing variations (TTVs) of up to $\rm 60\, min$. These two planets were first identified by ${TESS}$, and we identified a third planet in the ${TESS}$photometry with a period of $\rm 22.8911 \pm 0.0004~d$. We confirm the planetary nature of all three planetary candidates using ground-based photometry from Hazelwood, ${ASTEP}$, and LCO, including a full detection of the $\rm \sim 9\, h$ transit of HD 28109 c from Antarctica. The radii of the three planets are ${\it R}b=2.199{-0.10}^{+0.098} ~{\rm R}{\oplus }$, ${\it R}c=4.23\pm 0.11~ {\rm R}{\oplus }$, and ${\it R}d=3.25\pm 0.11 ~{\rm R}{\oplus }$; we characterize their masses using TTVs and precise radial velocities from ESPRESSO and HARPS, and find them to be ${\it M}b=18.5{-7.6}^{+9.1}~M{\oplus }$, ${\it M}c=7.9{-3.0}^{+4.2}~{\rm M}{\oplus }$, and ${\it M}d=5.7{-2.1}^{+2.7}~{\rm M}_{\oplus }$, making planet b a dense, massive planet while c and d are both underdense. We also demonstrate that the two outer planets are ripe for atmospheric characterization using transmission spectroscopy, especially given their position in the CVZ of James Webb Space Telescope. The data obtained to date are consistent with resonant (librating) and non-resonant (circulating) solutions; additional observations will show whether the pair is actually locked in resonance or just near-resonant. |
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1066 |
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0035-8711 |
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yes |
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8370 |
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Author |
Morin S, Erbland J, Savarino J, Domine F, Bock J, Friess U, Jacobi H-W, Sihler H, Martins J M F, |
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Title |
An isotopic view on the connection between photolytic emissions of NOx from the Arctic snowpack and its oxidation by reactive halogens
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Type |
Journal Article |
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Year |
2012 |
Publication |
J. Geophys. Res. |
Abbreviated Journal |
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Volume |
117 |
Issue |
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Pages |
D00R08- |
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Keywords |
halogen, isotopes, nitrate, ozone, 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906), 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry, 0454 Biogeosciences: Isotopic composition and chemistry (1041, 4870), 0736 Cryosphere: Snow (1827, 1863), 9315 Geographic Location: Arctic region (0718, 4207), |
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Abstract |
We report on dual isotopic analyses (δ15N and Δ17O) of atmospheric nitrate at daily time-resolution during the OASIS intensive field campaign at Barrow, Alaska, in March–April 2009. Such measurements allow for the examination of the coupling between snowpack emissions of nitrogen oxides (NOx = NO + NO2) and their involvement in reactive halogen-mediated chemical reactions in the Arctic atmosphere. The measurements reveal that during the spring, low δ15N values in atmospheric nitrate, indicative of snowpack emissions of NOx, are almost systematically associated with local oxidation of NOx by reactive halogens such as BrO, as indicated by 17O-excess measurements (Δ17O). The high time-resolution data from the intensive field campaign were complemented by weekly aerosol sampling between April 2009 and February 2010. The dual isotopic composition of nitrate (δ15N and Δ17O) obtained throughout this nearly full seasonal cycle is presented and compared to other seasonal-scale measurements carried out in the Arctic and in non-polar locations. In particular, the data allow for the investigation of the seasonal variations of reactive halogen chemistry and photochemical snowpack NOx emissions in the Arctic. In addition to the well characterized peak of snowpack NOx emissions during springtime in the Arctic (April to May), the data reveal that photochemical NOx emissions from the snowpack may also occur in other seasons as long as snow is present and there is sufficient UV radiation reaching the Earth's surface.
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1017 |
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AGU |
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ISSN |
0148-0227 |
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yes |
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Serial |
1881 |
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Author |
Gabriel Munoz, Pierre Labadie, Emmanuel Geneste, Patrick Pardon, Sabrina Tartu, Olivier Chastel, Hélène Budzinski |
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Title |
Biomonitoring of fluoroalkylated substances in Antarctica seabird plasma: Development and validation of a fast and rugged method using on-line concentration liquid chromatography tandem mass spectrometry |
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Journal |
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Year |
2017 |
Publication |
Journal of Chromatography A |
Abbreviated Journal |
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Volume |
1513 |
Issue |
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Pages |
107-117 |
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Keywords |
Antarctica Biomonitoring Method validation On-line solid phase extraction Plasma Polyfluoroalkyl substances Seabird |
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Abstract |
We report on a fast, accurate and rugged analytical procedure to determine a wide span of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in seabird plasma. The 26 investigated compounds included perfluoroalkyl carboxylates (C5–C14 PFCAs), perfluoroalkyl sulfonates (C4, C6, C7, C8, C10 PFSAs), perfluorooctane sulfonamide (FOSA) and N-alkyl derivatives (MeFOSA, EtFOSA), N-alkyl perfluorooctane sulfonamido acetic acids (MeFOSAA, EtFOSAA), fluorotelomer sulfonates (4:2 FTSA, 6:2 FTSA, 8:2 FTSA), polyfluoroalkyl phosphate diesters (diPAPs) and perfluorooctane sulfonamide phosphate diester (diSAmPAP). The method described herein requires a reduced sample amount (25μL) and involves rapid and simple sample preparation (protein precipitation with acetonitrile but without acidification) prior to analysis by on-line solid phase extraction (Oasis HLB sorbent) coupled to high performance liquid chromatography negative electrospray ionization tandem mass spectrometry. The optimization was conducted using experimental designs to account for potential interactions between variables. Out of the 26 target analytes, 23 compounds showed excellent accuracy (±25% of the expected values). Intermediate precision and matrix effects remained acceptable for most analytes thanks to efficient internal standardization. A human serum standard reference material (NIST SRM 1957) was included in the validation scheme to evaluate method trueness, which proved satisfactory (│Z-scores│<2 for most compounds). Notwithstanding the small initial sample intake, limits of detection as low as 0.003–0.1ngg−1 plasma were obtained. This allowed the determination of 11 target PFASs in Antarctic seabird plasma samples. ΣPFASs in Antarctic seabird plasma ranged from 0.37 to 19ngg−1, with a predominance of PFOS (>54% of ΣPFASs on average). The reduced plasma amount required implies that the present method could also be applied to the analysis of PFASs in the plasma of smaller biological models. |
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Programme |
109 |
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ISSN |
0021-9673 |
ISBN |
0021-9673 |
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yes |
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Serial |
7172 |
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Author |
Samara Danel, Gaël Bardon, Christophe de Franceschi, Léna Bureau, Christophe Barbraud, Karine Delord, Dora Biro, Francesco Bonadonna |
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Title |
Plant consumer innovation in skuas |
Type |
Journal |
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Year |
2023 |
Publication |
Journal of Ornithology |
Abbreviated Journal |
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Volume |
164 |
Issue |
3 |
Pages |
717-719 |
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Keywords |
Animal innovation Consumer innovation Field observation Novel food Stercorarius antarcticus lonnbergi |
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Abstract |
We report observations of alien dandelion (Taraxacum officinale group) consumption in an opportunistic predatory seabird, the brown skua (Stercorarius antarcticus lonnbergi), from a natural population on île Verte within the Kerguelen archipelago. Observations on a nearby island suggest that this behaviour is not specific to our study area, paving the way to future studies investigating whether this consumer innovation prevails in skua populations and results in dietary benefits. |
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Programme |
109,354 |
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Bachelor's thesis |
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ISSN |
2193-7206 |
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yes |
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Call Number |
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Serial |
8635 |
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Author |
François Fripiat, Daniel M. Sigman, Guillaume Massé, Jean-Louis Tison |
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Title |
High turnover rates indicated by changes in the fixed N forms and their stable isotopes in Antarctic landfast sea ice |
Type |
Journal |
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Year |
2015 |
Publication |
Journal of Geophysical Research: Oceans |
Abbreviated Journal |
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Volume |
120 |
Issue |
4 |
Pages |
3079-3097 |
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Keywords |
Antarctic isotopes nitrogen nutrients sea ice |
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Abstract |
We report concentration and nitrogen and oxygen isotopic measurements of nitrate, total dissolved nitrogen, and particulate nitrogen from Antarctic landfast sea ice, covering almost the complete seasonal cycle of sea ice growth and decay (from April to November). When sea ice forms in autumn, ice algae growth depletes nitrate and accumulates organic N within the ice. Subsequent low biological activity in winter imposes minor variations in the partitioning of fixed N. In early spring, the coupling between nitrate assimilation and brine convection at the sea ice bottom traps a large amount of fixed N within sea ice, up to 20 times higher than in the underlying seawater. At this time, remineralization and nitrification also accelerate, yielding nitrate concentrations up to 5 times higher than in seawater. Nitrate δ15N and δ18O are both elevated, indicating a near-balance between nitrification and nitrate assimilation. These findings require high microbially mediated turnover rates for the large fixed N pools, including nitrate. When sea ice warms in the spring, ice algae grow through the full thickness of the ice. The warming stratifies the brine network, which limits the exchange with seawater, causing the once-elevated nitrate pool to be nearly completely depleted. The nitrate isotope data point to light limitation at the base of landfast ice as a central characteristic of the environment, affecting its N cycling (e.g., allowing for nitrification) and impacting algal physiology (e.g., as reflected in the N and O isotope effects of nitrate assimilation). |
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Programme |
1010 |
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ISSN |
2169-9291 |
ISBN |
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Approved |
yes |
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Call Number |
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Serial |
8142 |
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Author |
Encelyn Voisine, Yann Rolland, Matthias Bernet, Julien Carcaillet, Guillaume Duclaux, Jérôme Bascou, Christian Sue, Mélanie Balvay, René-Pierre Ménot |
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Title |
Antarctic erosion history reconstructed by Terre Adélie moraine geochronology |
Type |
Journal |
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Year |
2020 |
Publication |
Antarctic Science |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
1-14 |
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Keywords |
cosmogenic nuclide dating deglaciation exhumation fission-track dating Late Palaeozoic Ice Age subglacial incision |
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Abstract |
We report apatite fission-track and 10Be terrestrial cosmogenic nuclide (TCN) dating of 14 moraine boulders originating from inland Terre Adélie, East Antarctica. These data show cooling of the Proterozoic Terre Adélie craton at < ~120°C between 350 and 300 Ma, suggesting > 4 km temperate glacial erosion during the Late Palaeozoic Ice Age, followed by nearly null Mesozoic erosion and low glacial erosion (< 2 km) in the Cenozoic. Based on glacial flux maps, the origin of the boulders may be located ~400 km upstream. Preliminary TCN (10Be) datings of moraine boulders cluster within the last 30 ka. Cosmogenic ages from the Lacroix Nunatak suggest a main deglaciation after the Younger Dryas at c. 10 ka, while those of Cap Prud'homme mostly cluster at 0.6 ka, in agreement with an exhumation of boulders during the Little Ice Age. |
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1003 |
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ISSN |
0954-1020, 1365-2079 |
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yes |
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Call Number |
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Serial |
7692 |
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Author |
Francia, P.; Lanzerotti, L.J.; Villante, U.; Lepidi, S.; Di Memmo, D. |
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Title |
A statistical analysis of low-frequency magnetic pulsations at cusp and cap latitudes in Antarctica |
Type |
Journal Article |
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Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
110 |
Issue |
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Pages |
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Keywords |
polar cap and cusp pulsations; magnetospheric wave guide modes; field line resonances; open/closed field line boundary; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2740 Magnetospheric Physics: Magnetospheric configuration and dynamics; 2776 Magnetospheric Physics: Polar cap phenomena; 2706 Magnetospheric Physics: Cusp; 2752 Magnetospheric Physics: MHD waves and instabilities |
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Abstract |
We report a statistical analysis of low-frequency magnetic variations (magnetic pulsations, 0.8–7 mHz) at South Pole (74°S corrected geomagnetic latitude) and Terra Nova Bay (80°S) during 1996. The results show that at South Pole (at cusp latitudes) the pulsation power exhibits two maxima during the day, one in the local premidnight and the other in the morning. The first maximum disappears when the analysis is restricted to northward interplanetary magnetic field conditions (B z > 1 nT), suggesting that it might be associated to substorm phenomena. During closed magnetospheric conditions, when the cusp is expected to be located poleward with respect to the station, the spectral and polarization characteristics of pulsations between 1 and 3 mHz suggest that resonant oscillations of the outermost closed field lines commonly occur at South Pole in the local morning. At Terra Nova Bay, in the polar cap, the pulsation power is much lower and its diurnal variation is characterized by a single maximum, which occurs around local noon, when the station approaches the cusp. The corresponding polarization pattern indicates that Terra Nova Bay is always located poleward with respect to resonant field lines. |
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1130 |
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Publisher |
American Geophysical Union |
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ISSN |
0148-0227 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5495 |
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Author |
Thébault, E.; Schott, J.J.; Mandea, M. |
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Title |
Revised spherical cap harmonic analysis (R-SCHA): Validation and properties |
Type |
Journal Article |
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Year |
2006 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
111 |
Issue |
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Pages |
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Keywords |
magnetism; regional modeling; Spherical Cap Harmonic Analysis; 1214 Geodesy and Gravity: Geopotential theory and determination; 1517 Geomagnetism and Paleomagnetism: Magnetic anomalies: modeling and interpretation; 1532 Geomagnetism and Paleomagnetism: Reference fields: regional, global; 1541 Geomagnetism and Paleomagnetism: Satellite magnetics: main field, crustal field, external field; 1545 Geomagnetism and Paleomagnetism: Spatial variations: all harmonics and anomalies |
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Abstract |
We recently proposed a technique able to represent the spatial variations of the magnetic field at regional scales. However, we pointed out that these preliminary developments were not suited for the complete representation of the geomagnetic field. In this paper, we propose a complete revision, the revised spherical cap harmonic analysis (R-SCHA), which introduces slight changes in order to rectify the previous shortcomings. In addition, some discussions shed a new light on the former spherical cap harmonic analysis (SCHA) and help us to demonstrate its deficiencies and approximations. We finally show that R-SCHA now fully satisfies the natural properties of potential fields. R-SCHA also yields analytical relationships with the spherical harmonics. Taking advantage of the mathematical equivalence of both representations, we explore the relevance of fundamental concepts like spectrum, minimum wavelength, or internal/external field separation. We conclude that these concepts are misleading and must be handled with care in regional modeling. A prime goal being the ability of R-SCHA to represent real data sets, we also investigate and illustrate the effect of finite series expansions. A norm for the regularization of the inverse problem is proposed as well. The conclusions drawn in this paper allow us to validate the method and to assert that the present proposal is suited for modeling and studying the lithospheric magnetic field from ground to satellite altitudes at regional scales. |
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139;905 |
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American Geophysical Union |
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0148-0227 |
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Approved |
yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5626 |
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Author |
Yushiro Fujii, Kenji Satake, Shingo Watada, Tung-Cheng Ho |
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Title |
Re-examination of Slip Distribution of the 2004 Sumatra–Andaman Earthquake (Mw 9.2) by the Inversion of Tsunami Data Using Green’s Functions Corrected for Compressible Seawater Over the Elastic Earth |
Type |
Journal |
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Year |
2021 |
Publication |
Pure and Applied Geophysics |
Abbreviated Journal |
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Volume |
178 |
Issue |
12 |
Pages |
4777-4796 |
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Keywords |
2004 Sumatra–Andaman earthquake far-field tsunami waveform phase-corrected Green’s function slip distribution tsunami data inversion |
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Abstract |
We re-examined the slip distribution on faults of the 2004 Sumatra–Andaman (M 9.1 according to USGS) earthquake by the inversion of tsunami data with phase-corrected Green’s functions applied to linear long waves. The correction accounts for the effects of compressibility of seawater, elasticity of solid earth, and gravitational potential variation associated with the motion of mass to reproduce the delayed arrivals and the reversed phase of the first tsunami waves. We used sea surface height (SSH) data from satellite altimetry (SA) measurements along five tracks, and the tsunami waveforms recorded at tide gauges (TGs) and ocean bottom pressure gauges (OBPGs) in and around the Indian Ocean. The inversion results for both data sets for different rupture velocities (Vr) show that the reproducibility of the spatiotemporal SSHs and tsunami waveforms is improved by the phase corrections, although the effects are not so significant within the Indian Ocean. The best slip distribution model from joint inversion of SA, TG and OBPG data with Vr of 1.3 km/s shows the largest slips of 16–25 m off Sumatra Island, large slips of 2–11 m off the Nicobar Islands, and moderate slips of 2–6 m in the Andaman Islands. The inversion results reproduce the far-field tsunami waveforms well at distant stations even more than 13,000–25,000 km from the epicenter. The total source length is about 1400 km and the seismic moment is Mw 9.2, longer and larger than that of our previous estimates based on TG records. |
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688 |
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ISSN |
1420-9136 |
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yes |
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Call Number |
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Serial |
8411 |
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Author |
Schimmel M, Stutzmann E, Ardhuin F, Gallart J, |
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Title |
Polarized Earth's ambient microseismic noise
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Type |
Journal Article |
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Year |
2011 |
Publication |
Geochemistry, Geophysics, Geosystems |
Abbreviated Journal |
1525-2027 |
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Volume |
12 |
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7 |
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Q07014- |
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Keywords |
microseismic noise, polarization, primary and secondary microseisms, seismology, 7255 Surface waves and free oscillations, 7299 General or miscellaneous, |
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Abstract |
We quantify, analyze, and characterize the frequency-dependent microseismic noise recorded by worldwide distributed seismic stations. Microseismic noise is generated through the interaction of ocean waves. It is the strongest ambient noise, and it is observed everywhere on Earth. We introduce a new approach which permits us to detect polarized signals in the time-frequency domain and which we use to characterize the microseismic noise. We analyze 7 years of continuous seismograms from the global GEOSCOPE network. Microseisms are dominated by Rayleigh waves, and we therefore focus on elliptically polarized signals. The polarized signals are detected in the time-frequency domain through a degree of polarization measure. We design polarization spectra and show that microseismic noise is more strongly polarized than noise in other frequency bands. This property is used to measure the directions of the polarized noise at individual stations as a function of time and frequency. Seasonal variations are found for the back azimuths and for the number of polarized signals at many stations. We show that the back azimuth directions are robust measurements that point toward the source areas computed from ocean wave models.
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133 |
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ISSN |
1525-2027 |
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Approved |
yes |
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Call Number |
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Serial |
725 |
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