The occurrence of planets and other substellar bodies around white dwarfs using K2

The majority of stars both host planetary systems and evolve into a white dwarf (WD). To understand their post-main-sequence (PMS) planetary system evolution, we present a search for transiting/eclipsing planets and other Substellar Bodies (SBs) around WDs using a sample of 1148 WDs observed by K2. Using transit injections, we estimate the completeness of our search. We place constraints on the occurrence of planets and substellar bodies around white dwarfs as a function of planet radius and orbital period. For short-period ($P < 40$ days) small objects, from asteroid-sized to $1.5 \ R_{\oplus}$, these are the strongest constraints known to date. We further constrain the occurrence of hot Jupiters ($< 1.5 \%$), habitable zone Earth-sized planets ($< 28 \%$), and disintegrating short-period planets ($\sim 12 \%$). We blindly recovered all previously known eclipsing objects, providing confidence in our analysis, and make all light curves publicly available.Comment: Accepted by MNRA

Attenuation by the debris disk of the solar-like star HD 107146 of a distant occulted galaxy

Observations of the debris disk around the solar-like star HD 107146 reveal the disk (nearly) transiting an extended background galaxy. By using out-of-transit observations to model the galaxy, we show it to be smooth and well modelable. When subtracting this model from the edge-of-transit observation, attenuation by dust of the debris disk in the line-of-sight can be seen. From this we calculate the column density of the dust. The results of this new way of detecting debris dust agree with previous work, however at increasing distance from the star we find an increasing column density, suggesting dust segregation

Spectroscopic Transit Search: a self-calibrating method for detecting planets around bright stars

We search for transiting exoplanets around the star $\beta$ Pictoris using high resolution spectroscopy and Doppler imaging that removes the need for standard star observations. These data were obtained on the VLT with UVES during the course of an observing campaign throughout 2017 that monitored the Hill sphere transit of the exoplanet $\beta$ Pictoris b. We utilize line profile tomography as a method for the discovery of transiting exoplanets. By measuring the exoplanet distortion of the stellar line profile, we remove the need for reference star measurements. We demonstrate the method with white noise simulations, and then look at the case of $\beta$ Pictoris, which is a $\delta$ Scuti pulsator. We describe a method to remove the stellar pulsations and perform a search for any transiting exoplanets in the resultant data set. We inject fake planet transits with varying orbital periods and planet radii into the spectra and determine the recovery fraction. In the photon noise limited case we can recover planets down to a Neptune radius with an $\sim$80% success rate, using an 8 m telescope with a $R\sim 100,000$ spectrograph and 20 minutes of observations per night. The pulsations of $\beta$ Pictoris limit our sensitivity to Jupiter-sized planets, but a pulsation removal algorithm improves this limit to Saturn-sized planets. We present two planet candidates, but argue that their signals are most likely caused by other phenomena. We have demonstrated a method for searching for transiting exoplanets that (i) does not require ancillary calibration observations, (ii) can work on any star whose rotational broadening can be resolved with a high spectral dispersion spectrograph and (iii) provides the lowest limits so far on the radii of transiting Jupiter-sized exoplanets around $\beta$ Pictoris with orbital periods from 15 days to 200 days with >50% coverage.Comment: Accepted for publication in A&A, 8 pages, 8 figures. The Github repository can be found at https://github.com/lennartvansluijs/Spectroscopic-Transit-Searc

Into the red: An M-band study of the chemistry and rotation of β Pictoris b at high spectral resolution

High-resolution cross-correlation spectroscopy (HRCCS) combined with adaptive optics has been enormously successful in advancing our knowledge of exoplanet atmospheres, from chemistry to rotation and atmospheric dynamics. This powerful technique now drives major science cases for ELT instrumentation including METIS/ELT, GMTNIRS/GMT and MICHI/TMT, targeting biosignatures on rocky planets at 3–5 μm, but remains untested beyond 3.5 μm where the sky thermal background begins to provide the dominant contribution to the noise. We present 3.51–5.21 μm M-band CRIRES+/VLT observations of the archetypal young directly imaged gas giant β Pictoris b, detecting CO absorption at S/N = 6.6 at 4.73 μm and H2O at S/N = 5.7, and thus extending the use of HRCCS into the thermal background noise dominated infrared. Using this novel spectral range to search for more diverse chemistry we report marginal evidence of SiO at S/N = 4.3, potentially indicative that previously proposed magnesium-silicate clouds in the atmosphere are either patchy, transparent at M-band wavelengths, or possibly absent on the planetary hemisphere observed. The molecular detections are rotationally broadened by the spin of β Pic b, and we infer a planetary rotation velocity of vsin(i) = 22 ± 2 km s−1 from the cross-correlation with the H2O model template, consistent with previous K-band studies. We discuss the observational challenges posed by the thermal background and telluric contamination in the M-band, the custom analysis procedures required to mitigate these issues, and the opportunities to exploit this new infrared window for HRCCS using existing and next-generation instrumentation

Carbon monoxide emission lines reveal an inverted atmosphere in the ultra hot Jupiter WASP-33 b and indicate an eastward hot spot

We report the first detection of CO emission lines at high spectral resolution in the day-side infrared thermal spectrum of an exoplanet. These emission lines, found in the atmosphere of the ultra hot Jupiter WASP-33 b, provide unambiguous evidence of its thermal inversion layer. Using spectra from the MMT Exoplanet Atmosphere Survey (MEASURE, $R\sim15,000$), covering pre- and post-eclipse orbital phases ($0.33<\phi<0.73$), we performed a cross-correlation analysis with 1D PHOENIX model atmospheres to detect CO at S/N=7.9 at $v_{sys}=0.15^{+0.64}_{-0.65}$ km/s and $K_{p}=229.5^{+1.1}_{-1.0}$ km/s. However, using the framework of Cross-Correlation-to-log-Likelihood mapping, we further find that the spectral line depths, as probed by the scaling parameter, change with phase: the line contrast is larger after the eclipse than before. We then use the general circulation model SPARC/MITgcm post-processed by the 3D gCMCRT radiative transfer code and interpret this variation as due to an eastward-shifted hot spot. Before the eclipse, when the hot spot is facing Earth, the thermal profiles are shallower, leading to a smaller line depth despite greater overall flux. After the eclipse, the western part of the day-side is facing Earth, where the thermal profiles are much steeper, leading to larger line depth despite less overall flux. We thus demonstrate that even relatively moderate resolution spectra can be used to understand the 3D nature of close-in exoplanets, if assessed within the log-likelihood framework, and that resolution can be traded for photon collecting power when the induced Doppler-shift is sufficiently large. We highlight that CO in ultra hot Jupiters is a good probe of their thermal structure and corresponding dynamics, and does not suffer from stellar activity unlike some atomic species, such as iron, that also appear in the hot host star spectrum.Comment: 24 pages, 21 figures, submitted to MNRA

Cycladophora davisiana の古海洋学的意義 : 北太平洋亜寒帯に設置されたセディメント・トラップからの考察

第5回放散虫研究集会論文集A time-series sediment trap was deployed at 3,200m in the Bering Sea (StationAB) during August 1990 to August 1993.The trap samples were studied for seasonal fluxes of radiolarians. The seasonal flux patterns of total polycystine radiolarians showed maxima during spring or summer whereas fluxes of C.ycladophora davisiana davisiana Ehrenberg increased during fall. Morley and Hays (1983) interpreted that high % C d. davisiana values in the Sea of Okhotsk were related to their dwelling depth and characteristic oceanographic conditions in the subsurface layer. Our sediment trap data provide a new insight into the arguments proposed by Morley and Hays. Morley and Hays (1983) suggested that the spring radiolarian production was inhibited by the sea ice cover in the Sea of Okhotsk. However C d. davisiana should not be significantly affected by that because of the observed main fluxes of this species in the fall. Therefore, the high percent of C. d. davisiana seen in the core tops in the Sea of Okhotsk, as well as high latitude oceans during the glacial intervals, are considered to be due to seasonal sea ice cover Stylochlamydium venustum (Bailey) is one of the dominant radiolarian species in the Bering Sea.Although tentative for a definite seasonality, the possible spring fiux increase of this taxon might explain why % S. vemtstttm decreased during the glacials. Downcore change of % S. venttstum shows an opposite trend of what ％ C. d. davisiana does in the Bering Sea (Blueford, 1983.), suggesting that the spring increase of S. venustum could have been restricted by sea ice cover and/or melt water during the glacials

Locations, ages, sea surface temperature calculations with standard deviation, and paleolatitude values for sites used to calculate meridional temperature profiles for time slices in the Early (55–48 Ma) and Middle Eocene (45–39 Ma).

<p>Published paleolatitudes refer to values published by the original authors. Values in column paleolatitude.org and error are calculated using methods presented in this paper.</p><p>Locations, ages, sea surface temperature calculations with standard deviation, and paleolatitude values for sites used to calculate meridional temperature profiles for time slices in the Early (55–48 Ma) and Middle Eocene (45–39 Ma).</p

Plate reconstruction at 50 Ma, around the moment of the Early Eocene Climate Optimum, with the sites used for sea surface temperature estimates in Figs 1 and 5.

<p>Reconstruction made in <i>GPlates</i> from Seton and colleagues [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126946#pone.0126946.ref014" target="_blank">14</a>], with modifications as indicated in the main text, placed in the paleomagnetic reference frame of Torsvik and colleagues [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126946#pone.0126946.ref020" target="_blank">20</a>]. Absolute paleolongitude of the global plate motion chain is unconstrained, and irrelevant for paleoclimate reconstructions. Meridians are spaced with 30 degree intervals. Italic numbers 1–14 indicate the reconstructed locations of the sites used for a case study on Eocene meridional temperature, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126946#pone.0126946.g005" target="_blank">Fig 5</a>, and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126946#pone.0126946.t002" target="_blank">Table 2</a>.</p

A Paleolatitude Calculator for Paleoclimate Studies - Fig 1

<p>(A) Example of a plate circuit. The motion of India versus Eurasia cannot be directly constrained since these plates are bounded by a destructive plate boundary (trench). Relative motions between these plates can be reconstructed by restoring the opening history of the North Atlantic ocean between Eurasia and North America, the Central Atlantic Ocean between Africa and North America, and the Indian Ocean between India and Africa. With the relative positions of all these plates known through time, a paleomagnetic pole of one of these plates can be used to constrain all of these plates relative to the geodynamo. (B) schematic outline of plate and mantle motions and reference frames. Plates move relative to the mantle (plate tectonics), and plates and mantle together can undergo phases of motion relative to the liquid outer core (true polar wander). Both processes lead to motion of a rock record relative to the Earth’s spin axis, and hence both influence the angle of insolation that is relevant for paleoclimate study. Mantle reference frames <i>A-C</i> (see text for explanation of these frames) can only reconstruct plate motion relative to the mantle, but cannot reconstruct true polar wander. These frames are therefore used for analysis of geodynamics, but should not be used for paleoclimate studies. Instead, a paleomagnetic reference frame should be used. On geological timescales, the geodynamo coincides with the Earth’s spin axis. The orientation of the paleomagnetic field in a rock can be used to restore a rock record into its original paleolatitude relative to the spin axis.</p