We present adaptive optics imaging from the NIRC2 instrument on the Keck II telescope that resolves the exoplanet host (and lens) star as it separates from the brighter source star. These ...observations yield the K-band brightness of the lens and planetary host star, as well as the lens-source relative proper motion, , in the heliocentric reference frame. The measurement allows for the determination of the microlensing parallax vector, , which had only a single component determined by the microlensing light curve. The combined measurements of and KL provide the masses of the host star, , and planet, mp = 3.27 0.32MJupiter with a projected separation of 3.4 0.5 au. This confirms the tentative conclusion of a previous paper that this super-Jupiter mass planet, OGLE-2005-BLG-071Lb, orbits an M dwarf. Such planets are predicted to be rare by the core accretion theory and have been difficult to find with other methods, but there are two such planets with firm mass measurements from microlensing, and an additional 11 planetary microlens events with host mass estimates and planet mass estimates >2 Jupiter masses that could be confirmed by high angular follow-up observations. We also point out that OGLE-2005-BLG-071L has separated far enough from its host star that it should be possible to measure the host-star metallicity with spectra from a high angular resolution telescope such as Keck, the Very Large Telescope, the Hubble Space Telescope, or the James Webb Space Telescope.
Vps34 is a phosphoinositide 3-kinase (PI3K) class III isoform that has attracted major attention over the recent years because of its role in autophagy. Herein we describe the biological ...characterization of SAR405, which is a low-molecular-mass kinase inhibitor of Vps34 (KD 1.5 nM). This compound has an exquisite protein and lipid kinase selectivity profile that is explained by its unique binding mode and molecular interactions within the ATP binding cleft of human Vps34. To the best of our knowledge, this is the first potent and specific Vps34 inhibitor described so far. Our results demonstrate that inhibition of Vps34 kinase activity by SAR405 affects both late endosome-lysosome compartments and prevents autophagy. Moreover, we show that the concomitant inhibition of Vps34 and mTOR, with SAR405 and the US Food and Drug Administration-approved mTOR inhibitor everolimus, results in synergistic antiproliferative activity in renal tumor cell lines, indicating a potential clinical application in cancer.
We present the analysis of high-resolution images of MOA-2013-BLG-220, taken with the Keck adaptive optics system six years after the initial observation, identifying the lens as a solar-type star ...hosting a super-Jupiter-mass planet. The masses of planets and host stars discovered by microlensing are often not determined from light-curve data, while the star-planet mass ratio and projected separation in units of Einstein ring radius are well measured. High-resolution follow-up observations after the lensing event is complete can resolve the source and lens. This allows direct measurements of flux, and the amplitude and direction of proper motion, giving strong constraints on the system parameters. Due to the high relative proper motion, mas yr−1, the source and lens were resolved in 2019, with a separation of 77.1 0.5 mas. Thus, we constrain the lens flux to . By combining constraints from the model and Keck flux, we find the lens mass to be at . With a mass ratio of the planet's mass is determined to be at a separation of . The lens mass is much higher than the prediction made by Bayesian analysis that assumes all stars have an equal probability to host a planet of the measured mass ratio, and suggests that planets with mass ratios of a few times 10−3 are more common orbiting massive stars. This demonstrates the importance of high-resolution follow-up observations for testing theories like these.
Abstract We revisit the planetary microlensing event OGLE-2013-BLG-0132/MOA-2013-BLG-148 using Keck adaptive optics imaging in 2013 with NIRC2 and in 2020, 7.4 yr after the event, with OSIRIS. The ...2020 observations yield a source and lens separation of 56.91 ± 0.29 mas, which provides us with a precise measurement of the heliocentric proper motion of the event μ rel,hel = 7.695 ± 0.039 mas yr −1 . We measured the magnitude of the lens in the K band as K lens = 18.69 ± 0.04. Using these constraints, we refit the microlensing light curve and undertake a full reanalysis of the event parameters including the microlensing parallax π E and the distance to the source D S . We confirm the results obtained in the initial study by Mróz et al. and improve significantly upon the accuracy of the physical parameters. The system is an M dwarf of 0.495 ± 0.054 M ⊙ orbited by a cold, Saturn-mass planet of 0.26 ± 0.028 M Jup at projected separation r ⊥ = 3.14 ± 0.28 au. This work confirms that the planetary system is at a distance of 3.48 ± 0.36 kpc, which places it in the Galactic disk and not the Galactic bulge.
Abstract
We measured the precise masses of the host and planet in the OGLE-2003-BLG-235 system, when the lens and source were resolving, with 2018 Keck high resolution images. This measurement is in ...agreement with the observation taken in 2005 with the Hubble Space Telescope (HST). In the 2005 data, the lens and sources were not resolved and the measurement was made using color-dependent centroid shift only. The Nancy Grace Roman Space Telescope will measure masses using data typically taken within 3–4 yr of the peak of the event, which is a much shorter baseline when compared to most of the mass measurements to date. Hence, the color-dependent centroid shift will be one of the primary methods of mass measurements for the Roman telescope. Yet, mass measurements of only two events (OGLE-2003-BLG-235 and OGLE-2005-BLG-071) have been done using the color-dependent centroid shift method so far. The accuracy of the measurements using this method are neither completely known nor well studied. The agreement of the Keck and HST results, as shown in this paper, is very important because this agreement confirms the accuracy of the mass measurements determined at a small lens-source separation using the color-dependent centroid shift method. It also shows that with >100 high resolution images, the Roman telescope will be able to use color-dependent centroid shift at a 3–4 yr time baseline and produce mass measurements. We find that OGLE-2003-BLG-235 is a planetary system that consists of a 2.34 ± 0.43
M
Jup
planet orbiting a 0.56 ± 0.06
M
⊙
K-dwarf host star at a distance of 5.26 ± 0.71 kpc from the Sun.
The EPOCH Project Kim, Dae-Won; Protopapas, Pavlos; Bailer-Jones, Coryn A L ...
Astronomy and astrophysics (Berlin),
06/2014, Letnik:
566
Journal Article
Recenzirano
Odprti dostop
The EPOCH (EROS-2 periodic variable star classification using machine learning) project aims to detect periodic variable stars in the EROS-2 light curve database. In this paper, we present the first ...result of the classification of periodic variable stars in the EROS-2 LMC database. To classify these variables, we first built a training set by compiling known variables in the Large Magellanic Cloud area from the OGLE and MACHO surveys. We crossmatched these variables with the EROS-2 sources and extracted 22 variability features from 28 392 light curves of the corresponding EROS-2 sources. We then used the random forest method to classify the EROS-2 sources in the training set. We designed the model to separate not only delta Scuti stars, RR Lyraes, Cepheids, eclipsing binaries, and long-period variables, the superclasses, but also their subclasses, such as RRab, RRc, RRd, and RRe for RR Lyraes, and similarly for the other variable types. The model trained using only the superclasses shows 99% recall and precision, while the model trained on all subclasses shows 87% recall and precision. We applied the trained model to the entire EROS-2 LMC database, which contains about 29 million sources, and found 117 234 periodic variable candidates. Out of these 117 234 periodic variables, 55 285 have not been discovered by either OGLE or MACHO variability studies. This set comprises 1906 delta Scuti stars, 6607 RR Lyraes, 638 Cepheids, 178 Type II Cepheids, 34562 eclipsing binaries, and 11 394 long-period variables.
Abstract
We report the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). We used the Hubble Space Telescope (HST) to carry out precise astrometry of the ...source star of the long-duration (
t
E
≃ 270 days), high-magnification microlensing event MOA-2011-BLG-191/OGLE-2011-BLG-0462 (hereafter designated as MOA-11-191/OGLE-11-462), in the direction of the Galactic bulge. HST imaging, conducted at eight epochs over an interval of 6 yr, reveals a clear relativistic astrometric deflection of the background star’s apparent position. Ground-based photometry of MOA-11-191/OGLE-11-462 shows a parallactic signature of the effect of Earth’s motion on the microlensing light curve. Combining the HST astrometry with the ground-based light curve and the derived parallax, we obtain a lens mass of 7.1 ± 1.3
M
⊙
and a distance of 1.58 ± 0.18 kpc. We show that the lens emits no detectable light, which, along with having a mass higher than is possible for a white dwarf or neutron star, confirms its BH nature. Our analysis also provides an absolute proper motion for the BH. The proper motion is offset from the mean motion of Galactic disk stars at similar distances by an amount corresponding to a transverse space velocity of ∼45 km s
−1
, suggesting that the BH received a “natal kick” from its supernova explosion. Previous mass determinations for stellar-mass BHs have come from radial velocity measurements of Galactic X-ray binaries and from gravitational radiation emitted by merging BHs in binary systems in external galaxies. Our mass measurement is the first for an isolated stellar-mass BH using any technique.
We present Keck/NIRC2 adaptive optics imaging of planetary microlensing event MOA-2007-BLG-400 that resolves the lens star system from the source. We find that the MOA-2007-BLG-400L planetary system ...consists of a 1.71 ± 0.27M(sub Jup) planet orbiting a 0.69 ± 0.04M⨀ K-dwarf host star at a distance of 6.89 ± 0.77 kpc from the Sun. So, this planetary system probably resides in the Galactic bulge. The planet–host star projected separation is only weakly constrained due to the close-wide light-curve degeneracy; the 2σ projected separation ranges are 0.6–1.0 au and 4.7–7.7 au for close and wide solutions, respectively. This host mass is at the top end of the range of masses predicted by a standard Bayesian analysis. Our Keck follow-up program has now measured lens-source separations for six planetary microlensing events, and five of these six events have host star masses above the median prediction under the assumption that assumes that all stars have an equal chance of hosting planets detectable by microlensing. This suggests that more massive stars may be more likely to host planets of a fixed mass ratio that orbit near or beyond the snow line. These results also indicate the importance of host star mass measurements for exoplanets found by microlensing. The microlensing survey imaging data from NASA’s Nancy Grace Roman Space Telescope (formerly WFIRST) mission will be doing mass measurements like this for a huge number of planetary events.
Abstract
We present an adaptive optics (AO) analysis of images from the Keck II telescope NIRC2 instrument of the planetary microlensing event MOA-2009-BLG-319. The ∼10 yr baseline between the event ...and the Keck observations allows the planetary host star to be detected at a separation of 66.5 ± 1.7 mas from the source star, consistent with the light-curve model prediction. The combination of the host star brightness and light-curve parameters yields host star and planet masses of
M
host
= 0.524 ± 0.048
M
⊙
and
m
p
= 67.3 ± 6.2
M
⊕
at a distance of
D
L
= 7.1 ± 0.7 kpc. The star−planet projected separation is 2.03 ± 0.21 au. The planet-to-star mass ratio of this system,
q
= (3.857 ± 0.029) × 10
−4
, places it in the predicted “planet desert” at 10
−4
<
q
< 4 × 10
−4
according to the runaway gas accretion scenario of the core accretion theory. Seven of the 30 planets in the Suzuki et al. sample fall in this mass ratio range, and this is the third with a measured host mass. All three of these host stars have masses of 0.5 ≤
M
host
/
M
⊙
≤ 0.7, which implies that this predicted mass ratio gap is filled with planets that have host stars within a factor of two of 1
M
⊙
. This suggests that runaway gas accretion does not play a major role in determining giant planet masses for stars somewhat less massive than the Sun. Our analysis has been accomplished with a modified DAOPHOT code that has been designed to measure the brightness and positions of closely blended stars. This will aid in the development of the primary method that the Nancy Grace Roman Space Telescope mission will use to determine the masses of microlens planets and their hosts.
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