Using Campaign 15 data from theK2mission, we have discovered a triply eclipsing triple star system: EPIC 249432662. The inner eclipsing binary system has a period of 8.23 d, withshallow∼3 per cent ...eclipses. During the entire 80-d campaign, there is also a single eclipse event of a third body in the system that reaches a depth of nearly 50 per cent and has a total duration of 1.7 d, longer than for any previously known third-body eclipse involving unevolved stars. The binary eclipses exhibit clear eclipse timing variations. A combination of photodynamical modeling of the light curve, as well as seven follow-up radial velocity measurements, has led to a prediction of the subsequent eclipses of the third star with a period of 188 d. A campaign of follow-up ground-based photometry was able to capture the subsequent pair of third-body events as well as two further 8-d eclipses. A combined photo-spectro-dynamical analysis then leads to the determination of many of the system parameters. The 8-d binary consists of a pair of M stars, while most of the system light is from a K star around which the pair of M stars orbits.
ABSTRACT
ASASSN-18am/SN 2018gk is a newly discovered member of the rare group of luminous, hydrogen-rich supernovae (SNe) with a peak absolute magnitude of MV ≈ −20 mag that is in between normal ...core-collapse SNe and superluminous SNe. These SNe show no prominent spectroscopic signatures of ejecta interacting with circumstellar material (CSM), and their powering mechanism is debated. ASASSN-18am declines extremely rapidly for a Type II SN, with a photospheric-phase decline rate of ∼6.0 mag (100 d)−1. Owing to the weakening of H i and the appearance of He i in its later phases, ASASSN-18am is spectroscopically a Type IIb SN with a partially stripped envelope. However, its photometric and spectroscopic evolution shows significant differences from typical SNe IIb. Using a radiative diffusion model, we find that the light curve requires a high synthesized 56Ni mass $M_{\rm Ni} \sim 0.4\, \rm {M_{\odot }}$ and ejecta with high kinetic energy Ekin = (7–10) × 1051 erg. Introducing a magnetar central engine still requires $M_{\rm Ni} \sim 0.3\, \rm {M_{\odot }}$ and Ekin = 3 × 1051 erg. The high 56Ni mass is consistent with strong iron-group nebular lines in its spectra, which are also similar to several SNe Ic-BL with high 56Ni yields. The earliest spectrum shows ‘flash ionization’ features, from which we estimate a mass-loss rate of $\dot{M}\approx 2\times 10^{-4} \, \rm \rm {M_{\odot }}\,yr^{-1}$. This wind density is too low to power the luminous light curve by ejecta–CSM interaction. We measure expansion velocities as high as 17 000 $\rm {\, km\, s^{-1}}$ for Hα, which is remarkably high compared to other SNe II. We estimate an oxygen core mass of 1.8–3.4 M⊙ using the O i luminosity measured from a nebular-phase spectrum, implying a progenitor with a zero-age main-sequence mass of 19–26 M⊙.
ABSTRACT The DEdicated MONitor of EXotransits (DEMONEX) was a 20-inch robotic and automated telescope to monitor bright stars hosting transiting exoplanets to discover new planets and improve ...constraints on the properties of known transiting planetary systems. We present results for the misaligned hot Jupiter XO-4b containing seven new transits from the DEMONEX telescope, including three full and four partial transits. We combine these data with archival light curves and archival radial velocity measurements to derive the host star mass and radius , the planet mass and radius , and a refined ephemeris of days and . We include archival Rossiter-McLaughlin measurements of XO-4 to infer the stellar spin-planetary orbit alignment of degrees. We test the effects of including various detrend parameters, theoretical and empirical mass-radius relations, and Rossiter-McLaughlin models. We infer that detrending against CCD position and time or airmass can improve data quality but can have significant effects on the inferred values of many parameters-most significantly and the observed central transit times TC. In the case of we find that the systematic uncertainty due to detrending can be three times that of the quoted statistical uncertainties. The choice of mass-radius relation has little effect on our inferred values of the system parameters. The choice of Rossiter-McLaughlin models can have significant effects on the inferred values of and the stellar spin-planet orbit angle λ.
The Transiting Exoplanet Survey Satellite (TESS) provides a continuous suite of new planet candidates that need confirmation and precise mass determination from ground-based observatories. This is ...the case for the G-type star TOI-1710, which is known to host a transiting sub-Saturn planet ( M p = 28.3 ± 4.7 M ⊕ ) in a long-period orbit ( P = 24.28 days). Here we combine archival SOPHIE and new and archival HARPS-N radial velocity data with newly available TESS data to refine the planetary parameters of the system and derive a new mass measurement for the transiting planet, taking into account the impact of the stellar activity on the mass measurement. We report for TOI-1710b a radius of R p = 5.15 ± 0.12 R ⊕ , a mass of M p = 18.4 ± 4.5 M ⊕ , and a mean bulk density of ρ p = 0.73 ± 0.18 g cm −3 , which are consistent at 1.2 σ , 1.5 σ , and 0.7 σ , respectively, with previous measurements. Although there is not a significant difference in the final mass measurement, we needed to add a Gaussian process component to successfully fit the radial velocity dataset. This work illustrates that adding more measurements does not necessarily imply a better mass determination in terms of precision, even though they contribute to increasing our full understanding of the system. Furthermore, TOI-1710b joins an intriguing class of planets with radii in the range 4–8 R ⊕ that have no counterparts in the Solar System. A large gaseous envelope and a bright host star make TOI-1710b a very suitable candidate for follow-up atmospheric characterization.
We present the first results from a reverberation-mapping campaign undertaken during the first half of 2012, with additional data on one active galactic nucleus (AGN) (NGC 3227) from a 2014 campaign. ...Our main goals are (1) to determine the black hole masses from continuum-Hβ reverberation signatures, and (2) to look for velocity-dependent time delays that might be indicators of the gross kinematics of the broad-line region. We successfully measure Hβ time delays and black hole masses for five AGNs, four of which have previous reverberation mass measurements. The values measured here are in agreement with earlier estimates, though there is some intrinsic scatter beyond the formal measurement errors. We observe velocity-dependent Hβ lags in each case, and find that the patterns have changed in the intervening five years for three AGNs that were also observed in 2007.
We present the first results from an optical reverberation mapping campaign executed in 2014 targeting the active galactic nuclei (AGNs) MCG+08-11-011, NGC 2617, NGC 4051, 3C 382, and Mrk 374. Our ...targets have diverse and interesting observational properties, including a "changing look" AGN and a broad-line radio galaxy. Based on continuum-Hβ lags, we measure black hole masses for all five targets. We also obtain Hγ and He ii λ4686 lags for all objects except 3C 382. The He ii λ4686 lags indicate radial stratification of the BLR, and the masses derived from different emission lines are in general agreement. The relative responsivities of these lines are also in qualitative agreement with photoionization models. These spectra have extremely high signal-to-noise ratios (100-300 per pixel) and there are excellent prospects for obtaining velocity-resolved reverberation signatures.
We present optical continuum lags for two Seyfert 1 galaxies, MCG+08-11-011 and NGC 2617, using monitoring data from a reverberation mapping campaign carried out in 2014. Our light curves span the ...ugriz filters over four months, with median cadences of 1.0 and 0.6 days for MCG+08-11-011 and NGC 2617, respectively, combined with roughly daily X-ray and near-UV data from Swift for NGC 2617. We find lags consistent with geometrically thin accretion-disk models that predict a lag-wavelength relation of τ ∝ λ4/3. However, the observed lags are larger than predictions based on standard thin-disk theory by factors of 3.3 for MCG+08-11-011 and 2.3 for NGC 2617. These differences can be explained if the mass accretion rates are larger than inferred from the optical luminosity by a factor of 4.3 in MCG+08-11-011 and a factor of 1.3 in NGC 2617, although uncertainty in the SMBH masses determines the significance of this result. While the X-ray variability in NGC 2617 precedes the UV/optical variability, the long (2.6 day) lag is problematic for coronal reprocessing models.
We present the first results from a reverberation-mapping campaign undertaken during the first half of 2012, with additional data on one AGN (NGC 3227) from a 2014 campaign. Our main goals are (1) to ...determine the black hole masses from continuum-Hbeta reverberation signatures, and (2) to look for velocity-dependent time delays that might be indicators of the gross kinematics of the broad-line region. We successfully measure Hbeta time delays and black hole masses for five AGNs, four of which have previous reverberation mass measurements. The values measured here are in agreement with earlier estimates, though there is some intrinsic scatter beyond the formal measurement errors. We observe velocity dependent Hbeta lags in each case, and find that the patterns have changed in the intervening five years for three AGNs that were also observed in 2007.
Electronic devices and instruments generate heat that can cause serious damage and low efficiency towards its components. The heat that the different electronic elements and components emit can ...decrease both efficiency and life capacity of the device. And with the increase of use of electronic devices in industries and processes, heat dissipation in electronic devices should be taken into strict consideration. This study aims to develop a cooling system under vapor compression refrigeration system. The prototype fabricated was designed for the cooling system of two Central Processing Units of desktop computer which can be as good equivalent for the electronic devices in industries. Though ventilation was present in the processing units, certain condition such as condition in surroundings can be of great help to improve the device efficiency. This study also aims to analyze the CPU’s efficiency in relation to lowering ventilation temperatures. The vapor compression refrigeration system will be the main device used for lowering and maintaining a suitable temperature inside the CPU casing. The system works like a centralized air-conditioning system wherein the air from the surroundings will be cooled down by the evaporator in the vapor compression refrigeration system. The cooled air will then be delivered to the CPU through the installed air ducting connections. The recording of CPU’s efficiency is provided by the installed software. It also measures the air conditioned parameters and computation of the CPU power consumption. The results from the test and the analysis of the gathered data showed that 165 watts of heat dissipated was removed by the cooling system and the CPU performance index rose up from 424 to 446 with a discharge air temperature of 29.67 oC. Based from the result, the fabricated binary cooling system is efficient enough to increase the performance index of the CPU and absorbing heat dissipated by the device.
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