We present the most sensitive direct imaging and radial velocity (RV) exploration of ɛ Eridani to date. ɛ Eridani is an adolescent planetary system, reminiscent of the early solar system. It is ...surrounded by a prominent and complex debris disk that is likely stirred by one or several gas giant exoplanets. The discovery of the RV signature of a giant exoplanet was announced 15 yr ago, but has met with scrutiny due to possible confusion with stellar noise. We confirm the planet with a new compilation and analysis of precise RV data spanning 30 yr, and combine it with upper limits from our direct imaging search, the most sensitive ever performed. The deep images were taken in the Ms band (4.7 μm) with the vortex coronagraph recently installed in W.M. Keck Observatory’s infrared camera NIRC2, which opens a sensitive window for planet searches around nearby adolescent systems. The RV data and direct imaging upper limit maps were combined in an innovative joint Bayesian analysis, providing new constraints on the mass and orbital parameters of the elusive planet. ɛ Eridani b has a mass of {0.78}SUB-0.12/SUBSUP+0.38/SUP M SUBJup/SUB and is orbiting ɛ Eridani at about 3.48 ± 0.02 au with a period of 7.37 ± 0.07 yr. The eccentricity of ɛ Eridani b’s orbit is {0.07}SUB-0.05/SUBSUP+0.06/SUP, an order of magnitude smaller than early estimates and consistent with a circular orbit. We discuss our findings from the standpoint of planet–disk interactions and prospects for future detection and characterization with the James Webb Space Telescope. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time was granted for this project by Caltech, the University of Hawai’i, the University of California, and NASA.
We present the most sensitive direct imaging and radial velocity (RV) exploration of \(\epsilon\) Eridani to date. \(\epsilon\) Eridani is an adolescent planetary system, reminiscent of the early ...Solar system. It is surrounded by a prominent and complex debris disk which is likely stirred by one or several gas giant exoplanets. The discovery of the RV signature of a giant exoplanet was announced 15 years ago, but has met with scrutiny due to possible confusion with stellar noise. We confirm the planet with a new compilation and analysis of precise RV data spanning 30 years, and combine it with upper limits from our direct imaging search, the most sensitive ever performed. The deep images were taken in the Ms band (4.7\(\mu\)m) with the vortex coronagraph recently installed in W.M. Keck Observatory's infrared camera NIRC2, which opens a sensitive window for planet searches around nearby adolescent systems. The RV data and direct imaging upper limit maps were combined in an innovative joint Bayesian analysis, providing new constraints on the mass and orbital parameters of the elusive planet. \(\epsilon\) Eridani b has a mass of \(0.78^{+0.38}_{-0.12}\) \(M_{Jup}\) and is orbiting \(\epsilon\) Eridani at about \(3.48\pm 0.02\) AU with a period of \(7.37 \pm 0.07\) years. The eccentricity of \(\epsilon\) Eridani b's orbit is \(0.07^{+0.06}_{-0.05}\), an order of magnitude smaller than early estimates and consistent with a circular orbit. We discuss our findings from the standpoint of planet-disk interactions and prospects for future detection and characterization with the James Webb Space Telescope.
We present infrared observations of the ultra-compact H II region W3(OH) made by the FORCAST instrument aboard SOFIA and by Spitzer/IRAC. We contribute new wavelength data to the spectral energy ...distribution, which constrains the optical depth, grain size distribution, and temperature gradient of the dusty shell surrounding the H II region. We model the dust component as a spherical shell containing an inner cavity with radius ~ 600 AU, irradiated by a central star of type O9 and temperature ~ 31,000 K. The total luminosity of this system is 71,000 L_solar. An observed excess of 2.2 - 4.5 microns emission in the SED can be explained by our viewing a cavity opening or clumpiness in the shell structure whereby radiation from the warm interior of the shell can escape. We claim to detect the nearby water maser source W3 (H2O) at 31.4 and 37.1 microns using beam deconvolution of the FORCAST images. We constrain the flux densities of this object at 19.7 - 37.1 microns. Additionally, we present in situ observations of four young stellar and protostellar objects in the SOFIA field, presumably associated with the W3 molecular cloud. Results from the model SED fitting tool of Robitaille et al. (2006, 2007} suggest that two objects (2MASS J02270352+6152357 and 2MASS J02270824+6152281) are intermediate-luminosity (~ 236 - 432 L_solar) protostars; one object (2MASS J02270887+6152344) is either a high-mass protostar with luminosity 3000 L_solar or a less massive young star with a substantial circumstellar disk but depleted envelope; and one object (2MASS J02270743+6152281) is an intermediate-luminosity (~ 768 L_solar) protostar nearing the end of its envelope accretion phase or a young star surrounded by a circumstellar disk with no appreciable circumstellar envelope.
The relative contents of Epstein-Barr virus (EBV)-associated nuclear antigen (EBNA) and average numbers of EBV genome equivalents per cell were determined (i) in Raji cells superinfected with P3HR-1 ...virus, (ii) in Raji cells induced by 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and sodium n-butyrate and (iii) in P3HR-1 cells induced by TPA and sodium n-butyrate. This treatment was followed by increases in the percentage of early antigen (in both Raji and P3HR-1 cells) and virus capsid antigen-positive cells (in P3HR-1 cells) and increases of approximately 20-fold in the average number of EBV DNA equivalents in superinfected Raji cells and in TPA- and sodium n-butyrate-induced P3HR-1 cells. However, the content of EBNA in these cells dropped. This was revealed by a decrease in both the complement-fixing antigen content and in the proportion of EBNA-positive cells as determined by anti-complement immunofluorescence. Thus, the positive correlation found previously between the content of EBNA and the number of EBV genome equivalents per cell in proliferating lymphoblastoid cultures does not seem to apply to the situation in either superinfected Raji cells or in P3HR-1 cells induced by TPA and sodium n-butyrate.
The cytotoxicity of the nitric oxide donor, S-nitroso-N-acetyl-penicillamine (SNAP), towards cultured human cells from oral tissue was evaluated. The toxicity of SNAP to Smulow-Glickman gingival ...epithelial cells was correlated with the liberation of nitric oxide, as N-acetyl-D,L-penicillamine, the SNAP metabolites, N-acetyl-D,L-penicillamine disulfide and nitrite, and preincubated (denitrosylated) SNAP did not affect viability. Comparing equimolar concentrations of various nitric oxide donors, cytotoxicity appeared to be inversely related to the relative stability (i.e., half-life) of the test compound; the sequence of cytotoxicity for a 4 hr exposure was S-nitrosoglutathione>>spermine NONOate> SNAP>DPTA NONOate>>DETA NONOate. Intracellular reduced glutathione (GSH) was lowered in S-G cells exposed to SNAP. Pretreatment of the cells with the GSH depleter, 1,3-bis-(chloroethyl)-1-nitrosourea (BCNU), enhanced the toxicity of SNAP Similar findings of enhanced sensitivity to SNAP were noted with gingival fibroblasts and periodontal ligament cells pretreated with BCNU. The toxicity of SNAP towards the gingival epithelial cells was decreased by cotreatment with the antioxidants, N-acetyl-L-cysteine, L-ascorbic acid, and (+)-catechin. Cells exposed to SNAP exhibited nuclear aberrations, including multilobed nuclei and multinucleation. SNAP-induced cell death was apparently by apoptosis, as noted by fluorescence microscopy and DNA agarose gel electrophoresis.
: The cytotoxicity of the nitric oxide donor, S‐nitroso‐N‐acetyl‐penicillamine (SNAP), towards cultured human cells from oral tissue was evaluated. The toxicity of SNAP to Smulow‐Glickman gingival ...epithelial cells was correlated with the liberation of nitric oxide, as N‐acetyl‐D, L‐penicilIamine, the SNAP metabolites, N‐acetyl‐D, L‐penicillamine disulfide and nitrite, and preincubated (denilrosylated) SNAP did not affect viability. Comparing equimolar concentrations of various nitric oxide donors, cytotoxicity appeared to be inversely related to the relative stability (i.e., half‐life) of the test compound; the sequence of cytotoxicity for a 4 hr exposure was S‐nitrosoglutathione>>spermine NONOate> SNAP>DPTA NONOate>>DETA NONOate. Intracellular reduced glutathione (GSH) was lowered in S‐G cells exposed to SNAP. Pretreatment of the cells with the GSH depleter, 1, 3‐bis‐(chloroethyl)‐1‐nitrosourea (BCNU), enhanced the toxicity of SNAP. Similar findings of enhanced sensitivity to SNAP were noted with gingival fibroblasts and periodontal ligament cells pretreated with BCNU. The toxicity of SNAP towards the gingival epithelial cells was decreased by cotreatment with the antioxidants, N‐acetyl‐L‐cysteine, L‐ascorbic acid, and (+)‐catechin. Cells exposed to SNAP exhibited nuclear aberrations, including multilobed nuclei and multinucleation. SNAP‐induced cell death was apparently by apoptosis, as noted by fluorescence microscopy and DNA agarose gel electrophoresis.
Open clusters have been the focus of several exoplanet surveys, but only a few planets have so far been discovered. The Kepler spacecraft revealed an abundance of small planets around small cool ...stars, therefore, such cluster members are prime targets for exoplanet transit searches. Kepler's new mission, K2, is targeting several open clusters and star-forming regions around the ecliptic to search for transiting planets around their low-mass constituents. Here, we report the discovery of the first transiting planet in the intermediate-age (800 Myr) Beehive cluster (Praesepe). K2-95 is a faint (Kp = 15.5 mag) M3.0 +/- 0.5 dwarf from K2's Campaign 5 with an effective temperature of 3471 +/- 124 K, approximately solar metallicity and a radius of 0.402 +/- 0.050 R-circle dot. We detected a transiting planet with a radius of 3.47(-0.53)(+0.78)R(circle plus) and an orbital period of 10.134 days. We combined photometry, medium/high-resolution spectroscopy, adaptive optics/speckle imaging, and archival survey images to rule out any false-positive detection scenarios, validate the planet, and further characterize the system. The planet's radius is very unusual as M-dwarf field stars rarely have Neptune-sized transiting planets. The comparatively large radius of K2-95b is consistent with the other recently discovered cluster planets K2-25b (Hyades) and K2-33b (Upper Scorpius), indicating systematic differences in their evolutionary states or formation. These discoveries from K2 provide a snapshot of planet formation and evolution in cluster environments and thus make excellent laboratories to test differences between field-star and cluster planet populations.
We present 197 planet candidates discovered using data from the first year of the NASA K2 mission (Campaigns 0-4), along with the results of an intensive program of photometric analyses, stellar ...spectroscopy, high-resolution imaging, and statistical validation. We distill these candidates into sets of 104 validated planets (57 in multi-planet systems), 30 false positives, and 63 remaining candidates. Our validated systems span a range of properties, with median values of R-P = 2.3 R-circle plus, P = 8.6 days, T-eff = 5300 K, and Kp = 12.7 mag. Stellar spectroscopy provides precise stellar and planetary parameters for most of these systems. We show that K2 has increased by 30% the number of small planets known to orbit moderately bright stars (1-4 R-circle plus, Kp = 9-13. mag). Of particular interest are 76 planets smaller than 2 R-circle plus, 15 orbiting stars brighter than Kp = 11.5. mag, 5 receiving Earth-like irradiation levels, and several multi-planet systems-including 4 planets orbiting the M dwarf K2-72 near mean-motion resonances. By quantifying the likelihood that each candidate is a planet we demonstrate that our candidate sample has an overall false positive rate of 15%-30%, with rates substantially lower for small candidates (<2 R-circle plus) and larger for candidates with radii >8 R-circle plus and/or with P < 3 days. Extrapolation of the current planetary yield suggests that K2 will discover between 500 and 1000 planets in its planned four-year mission, assuming sufficient follow-up resources are available. Efficient observing and analysis, together with an organized and coherent follow-up strategy, are essential for maximizing the efficacy of planet-validation efforts for K2, TESS, and future large-scale surveys.
HD 3167 is a bright (V = 8.9), nearby KO star observed by the NASA K2 mission (EPIC 220383386), hosting two small, short-period transiting planets. Here we present the results of a multi-site, ...multi-instrument radial-velocity campaign to characterize the HD 3167 system. The masses of the transiting planets are 5.02 +/- 0.38 M-circle plus for HD 3167 b, a hot super-Earth with a likely rocky composition (rho(b) = 5.6(-1.43)(+2.15) g cm(-3)), and 9.80(-1.24)(+1.30) M-circle plus for HD 3167 c, a warm sub-Neptune with a likely substantial volatile complement (rho(c) = 1.97(-0.59)(+0.94) g cm(-3)). We explore the possibility of atmospheric composition analysis and determine that planet c is amenable to transmission spectroscopy measurements, and planet b is a potential thermal emission target. We detect a third, non-transiting planet, HD 3167 d, with a period of 8.509 +/- 0.045 d (between planets b and c) and a minimum mass of 6.90 +/- 0.71 M-circle plus. We are able to constrain the mutual inclination of planet d with planets b and c: we rule out mutual inclinations below 1.degrees 3 because we do not observe transits of planet d. From 1.degrees 3 to 40 degrees, there are viewing geometries invoking special nodal configurations, which result in planet d not transiting some fraction of the time.
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