Context. Stars can maintain their observable magnetic activity from the pre-main sequence (PMS) to the tip of the red giant branch. However, the number of known active giants is much lower than ...active stars on the main sequence (MS) since the stars spend only about 10% of their MS lifetime on the giant branch. Due to their rapid evolution it is difficult to estimate the stellar parameters of giant stars. A possibility for obtaining more reliable stellar parameters for an active giant arises when it is a member of an eclipsing binary system. Aims. We have discovered EPIC 211759736, an active spotted giant star in an eclipsing binary system during the Kepler K2 Campaign 5. The eclipsing nature allows us to much better constrain the stellar parameters than in most cases of active giant stars. Methods. We have combined the K2 data with archival HATNet, ASAS, and DASCH photometry, new spectroscopic radial velocity measurements, and a set of follow-up ground-based BVRCIC photometric observations, to find the binary system parameters as well as robust spot models for the giant at two different epochs. Results. We determined the physical parameters of both stellar components and provide a description of the rotational and long-term activity of the primary component. The temperatures and luminosities of both components were examined in the context of the Hertzsprung–Russell diagram. We find that both the primary and the secondary components deviate from the evolutionary tracks corresponding to their masses in the sense that the stars appear in the diagram at lower masses than their true masses. Conclusions. We further evaluate the proposition that traditional methods generally result in higher masses for active giants than what is indicated by stellar evolution tracks in the HR diagram. A possible reason for this discrepancy could be a strong magnetic field, since we see greater differences in more active stars.
We report the discovery of HAT-P-56b by the HATNet survey, an inflated hot Jupiter transiting a bright F-type star in Field 0 of NASA's K2 mission. We combine ground-based discovery and follow-up ...light curves with high precision photometry from K2, as well as ground-based radial velocities from the Tillinghast Reflector Echelle Spectrograph on the Fred Lawrence Whipple Observatory 1.5 m telescope to determine the physical properties of this system. HAT-P-56b has a mass of 2.18 M sub(J), radius of 1.47 R sub(J), and transits its host star on a near-grazing orbit with a period of 2.7908 day. The radius of HAT-P-56b is among the largest known for a planet with M sub(p) > 2 M sub(J). The host star has a V-band magnitude of 10.9, mass of 1.30 M sub(middot in circle), and radius of 1.43 R sub(middot in circle). The periodogram of the K2 light curve suggests that the star is a gamma Dor variable. HAT-P-56b is an example of a ground-based discovery of a transiting planet, where space-based observations greatly improve the confidence in the confirmation of its planetary nature, and also improve the accuracy of the planetary parameters.
We present a quintuple star system that contains two eclipsing binaries. The unusual architecture includes two stellar images separated by 11 arcsec on the sky: EPIC 212651213 and EPIC 212651234. The ...more easterly image (212651213) actually hosts both eclipsing binaries which are resolved within that image at 0.09 arcsec, while the westerly image (212651234) appears to be single in adaptive optics (AO), speckle imaging, and radial velocity (RV) studies. The ‘A’ binary is circular with a 5.1-d period, while the ‘B’ binary is eccentric with a 13.1-d period. The γ velocities of the A and B binaries are different by ∼10 km s−1. That, coupled with their resolved projected separation of 0.09 arcsec, indicates that the orbital period and separation of the ‘C’ binary (consisting of A orbiting B) are ≃65 yr and ≃25 au, respectively, under the simplifying assumption of a circular orbit. Motion within the C orbit should be discernible via future RV, AO, and speckle imaging studies within a couple of years. The C system (i.e. 212651213) has an RV and proper motion that differ from that of 212651234 by only ∼1.4 km s−1 and ∼3 mas yr−1. This set of similar space velocities in three dimensions strongly implies that these two objects are also physically bound, making this at least a quintuple star system.
We report the discovery and characterization of four transiting exoplanets by the HATNet survey. The planet HAT-P-50b has a mass of 1.35 M sub(J) and radius of 1.29 R sub(J), and orbits a bright (V = ...11.8 mag) M = 1.27 M sub(middot in circle), R = 1.70 R sub(middot in circle) star every P = 3.1220 days. The planet HAT-P-51b has a mass of 0.31 M sub(J) and radius of 1.29 R sub(J) and orbits a V = 13.4 mag, M = 0.98 M sub(middot in circle), R = 1.04 R sub(middot in circle) star with a period of P = 4.2180 days. The planet HAT-P-52b has a mass of 0.82M sub(J) and radius of 1.01 R sub(J), and orbits a V = 14.1 mag, M = 0.89 M sub(middot in circle), R = 0.89 R sub(middot in circle) star with a period of P = 2.7536 days. The planet HAT-P-53b has a mass of 1.48 M sub(J) and radius of 1.32 R sub(J), and orbits a V = 13.7 mag, M = 1.09 M sub(middot in circle), R = 1.21 R sub(middot in circle) star with a period of P = 1.9616 days. All four planets are consistent with having circular orbits and have masses and radii measured to better than 10% precision. The low stellar jitter and favorable Rp/Rlow * ratio for HAT-P-51 make it a promising target for measuring the Rossiter-McLaughlin effect for a Saturn-mass planet.
Background
Falls are a leading cause of injury and death for old adults, with one risk factor for falls being balance deficits. The low cost (<400 USD), wide availability, and ability to incorporate ...multiple training paradigms make gaming systems appealing as possible balance intervention tools.
Aims
To investigate the feasibility of using the Xbox Kinect for training to improve clinical measures of balance in old adults and retain improvements after a period of time.
Methods
Thirteen healthy old adults (aged 70+ years) were randomly divided into two groups. The experimental group completed Kinect training three times a week for 3 weeks while the control group continued with normal activities. Four clinical measures of balance were assessed before training, 1 week and 1 month after training: Berg balance scale (BBS), Fullerton advanced balance (FAB) scale, functional reach (FR), and timed up and go (TUG).
Results
The ability to implement the training program was successful. The experimental group significantly increased their BBS and FAB after training while the control group did not. There was no significant change for either groups with FR and TUG.
Conclusion
A training program using the Kinect with commercially available games was feasible with old adults. Kinect training may be an inexpensive way for old adults to receive helpful feedback encouraging them to continue with balance training program in their home.
Disks in binary systems can cause exotic eclipsing events. MWC 882 (BD -22 4376, EPIC 225300403) is such a disk-eclipsing system identified from observations during Campaign 11 of the K2 mission. We ...propose that MWC 882 is a post-Algol system with a B7 donor star of mass in a 72-day orbit around an A0 accreting star of mass . The disk around the accreting star occults the donor star once every orbit, inducing 19-day long, 7% deep eclipses identified by K2 and subsequently found in pre-discovery All-Sky Automated Survey and All Sky Automated Survey for Supernovae observations. We coordinated a campaign of photometric and spectroscopic observations for MWC 882 to measure the dynamical masses of the components and to monitor the system during eclipse. We found the photometric eclipse to be gray to 1%. We found that the primary star exhibits spectroscopic signatures of active accretion, and we observed gas absorption features from the disk during eclipse. We suggest that MWC 882 initially consisted of a 3.6 M donor star transferring mass via Roche lobe overflow to a 2.1 M accretor in a 7-day initial orbit. Through angular momentum conservation, the donor star is pushed outward during mass transfer to its current orbit of 72 days. The observed state of the system corresponds with the donor star having left the red giant branch ∼0.3 Myr ago, terminating active mass transfer. The present disk is expected to be short-lived (102 yr) without an active feeding mechanism, presenting a challenge to this model.
We report the discovery by the HATNet survey of three new transiting extrasolar planets orbiting moderately bright (V = 13.2, 12.8, and 11.9) stars. Each system shows significant systematic ...variations in its residual radial velocities, indicating the possible presence of additional components. Based on its Bayesian evidence, the preferred model for HAT-P-44 consists of two planets, including the transiting component, with the outer planet having a period of 872 days, eccentricity of 0.494 + or - 0.081, and a minimum mass of 4.0 M sub(J). For HAT-P-45, at present there is not enough data to justify the additional free parameters included in a multi-planet model; in this case a single-planet solution is preferred, but the required jitter of 22.5 + or - 6.3 ms super(-1) is relatively high for a star of this type. Continued radial velocity monitoring is necessary to fully characterize these three planetary systems, the properties of which may have important implications for understanding the formation of hot Jupiters.
ABSTRACT In this work, we report the detection of seven Neptune Trojans (NTs) in the Pan-STARRS 1 (PS1) survey. Five of these are new discoveries, consisting of four L4 Trojans and one L5 Trojan. Our ...orbital simulations show that the L5 Trojan stably librates for only several million years. This suggests that the L5 Trojan must be of recent capture origin. On the other hand, all four new L4 Trojans stably occupy the 1:1 resonance with Neptune for more than 1 Gyr. They can, therefore, be of primordial origin. Our survey simulation results show that the inclination width of the NT population should be between 7° and 27° at >95% confidence, and most likely ∼11°. In this paper, we describe the PS1 survey, the Outer Solar System pipeline, the confirming observations, and the orbital/physical properties of the new NTs.
To investigate the efficacy of perturbation-based balance training (PBBT) on time to stabilization (TTS) after a nonstepping response to a postural perturbation in older adults at a high risk for ...falls.
Single-subject design. Participants completed 4 baseline tests, 1 month of PBBT, and posttraining tests both 1 week and 1 month after training.
Assisted-living facility.
Older adults (N=5; mean ± SD age, 85±6.5y; residents of assisted-living facility) at a high risk for falls.
PBBT involved 3 sessions a week for 4 weeks. Each session involved standing for 50 trials on a pneumatic instrumented moving platform that translated 0 to 0.08m forward or 0 to 0.13m backward in approximately 390ms (average velocity, 0.25m/s).
Time to stabilization of center of pressure (COP) after a perturbation on the moving platform.
TTS of COP was 41.6% shorter than baseline tests (P<.001) 1 week after completing PBBT and 46.3% shorter than baseline tests (P<.001) 1 month after completing PBBT.
PBBT improved TTS after a postural perturbation in older adults at a high risk for falls, and these improvements were retained for 1 month.
We report the orbital distribution of the trans-Neptunian comets discovered during the first discovery year of the Canada-France Ecliptic Plane Survey (CFEPS). CFEPS is a Kuiper Belt object survey ...based on observations acquired by the Very Wide component of the Canada-France-Hawaii Telescope Legacy Survey (LS-VW). The first year's detections consist of 73 Kuiper Belt objects, 55 of which have now been tracked for three years or more, providing precise orbits. Although this sample size is small compared to the world-wide inventory, because we have an absolutely calibrated and extremely well-characterized survey (with known pointing history) we are able to de-bias our observed population and make unbiased statements about the intrinsic orbital distribution of the Kuiper Belt. By applying the (publically available) CFEPS Survey Simulator to models of the true orbital distribution and comparing the resulting simulated detections to the actual detections made by the survey, we are able to rule out several hypothesized Kuiper Belt object orbit distributions. We find that the main classical belt's so-called 'cold' component is confined in semimajor axis (a) and eccentricity (e) compared to the more extended 'hot' component; the cold component is confined to lower e and does not stretch all the way out to the 2:1 resonance but rather depletes quickly beyond a = 45 AU. For the cold main classical belt population we find a robust population estimate of N(Hg < 10) = 50 ± 5 X 103 and find that the hot component of the main classical belt represents ~60% of the total population. The inner classical belt (sunward of the 3:2 mean-motion resonance) has a population of roughly 2000 trans-Neptunian objects with absolute magnitudes Hg < 10, and may not share the inclination distribution of the main classical belt. We also find that the plutino population lacks a cold low-inclination component, and so, the population is somewhat larger than recent estimates; our analysis shows a plutino population of N(Hg < 10)~ 25+25 -12 X 103compared to our estimate of the size of main classical Kuiper Belt population of N(Hg < 10) ~ (126+50 -46) X 103.
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