As part of the Transit Ephemeris Refinement and Monitoring Survey, we present new radial velocities and photometry of the HD 192263 system. Our analysis of the already available Keck-HIRES and ...CORALIE radial velocity measurements together with the five new Keck measurements we report in this paper results in improved orbital parameters for the system. We derive constraints on the size and phase location of the transit window for HD 192263b, a Jupiter-mass planet with a period of 24.3587 + or - 0.0022 days. We use 10 years of Automated Photoelectric Telescope photometry to analyze the stellar variability and search for planetary transits. We find continuing evidence of spot activity with periods near 23.4 days. The shape of the corresponding photometric variations changes over time, giving rise to not one but several Fourier peaks near this value. However, none of these frequencies coincides with the planet's orbital period and thus we find no evidence of star-planet interactions in the system. We attribute the ~23 day variability to stellar rotation. There are also indications of spot variations on longer (8 years) timescales. Finally, we use the photometric data to exclude transits for a planet with the predicted radius of 1.09 R sub(J) and as small as 0.79 R sub(J).
This paper presents a case study both for individual process improvements and also for the improvement of the overall manufacturing flow, within an SME, using specialized simulation software called ...SigmaFlow Modeler. The improvements are done based on simulation results (accurate knowledge), meaning that by analyzing the process distribution charts, one can dispose measures for solving problems or even preventing potential failures. It has to be noted that by eliminating those bottlenecks the overall performance of the process will increase and the manufacturing flow will also be enhanced. The paper will also present an actual process simulation for the most complex process from the manufacturing cycle, i.e. the milling process, and a short analysis, focusing on possible improvements, will be performed on it. Moreover, further improvements will be done by closely reviewing and identifying every input and output and by introducing them into a cause-and-effect matrix, the importance of each input can be mathematically calculated and action can be taken for the critical ones in order to improve the process.
We discuss a Bayesian approach to the analysis of radial velocities in planet searches. We use a combination of exact and approximate analytic and numerical techniques to efficiently evaluate χ2 for ...multiple values of orbital parameters, and to carry out the marginalization integrals for a single planet including the possibility of a long-term trend. The result is a robust algorithm that is rapid enough for use in real-time analysis that outputs constraints on orbital parameters and false-alarm probabilities for the planet and long-term trend. The constraints on parameters and odds ratio that we derive compare well with previous calculations based on Markov Chain Monte Carlo methods, and we compare our results with other techniques for estimating false-alarm probabilities and errors in derived orbital parameters. False-alarm probabilities from the Bayesian analysis are systematically higher than frequentist false-alarm probabilities, due to the different accounting of the number of trials. We show that upper limits on the velocity amplitude derived for circular orbits are a good estimate of the upper limit on the amplitude of eccentric orbits for e≲ 0.5.
A key legacy of the recently launched the Transiting Exoplanet Survey Satellite (TESS) mission will be to provide the astronomical community with many of the best transiting exoplanet targets for ...atmospheric characterization. However, time is of the essence to take full advantage of this opportunity. The James Webb Space Telescope (JWST), although delayed, will still complete its nominal five year mission on a timeline that motivates rapid identification, confirmation, and mass measurement of the top atmospheric characterization targets from TESS. Beyond JWST, future dedicated missions for atmospheric studies such as the Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) require the discovery and confirmation of several hundred additional sub-Jovian size planets (Rp < 10 R⊕) orbiting bright stars, beyond those known today, to ensure a successful statistical census of exoplanet atmospheres. Ground-based extremely large telescopes (ELTs) will also contribute to surveying the atmospheres of the transiting planets discovered by TESS. Here we present a set of two straightforward analytic metrics, quantifying the expected signal-to-noise in transmission and thermal emission spectroscopy for a given planet, that will allow the top atmospheric characterization targets to be readily identified among the TESS planet candidates. Targets that meet our proposed threshold values for these metrics would be encouraged for rapid follow-up and confirmation via radial velocity mass measurements. Based on the catalog of simulated TESS detections by Sullivan et al., we determine appropriate cutoff values of the metrics, such that the TESS mission will ultimately yield a sample of ∼300 high-quality atmospheric characterization targets across a range of planet size bins, extending down to Earth-size, potentially habitable worlds.
Recent results from the Kepler mission indicate that super-Earths (planets with masses between 1-10 times that of the Earth) are the most common kind of planet around nearby Sun-like stars. These ...planets have no direct solar system analogue, and are currently one of the least well-understood classes of extrasolar planets. Many super-Earths have average densities that are consistent with a broad range of bulk compositions, including both water-dominated worlds and rocky planets covered by a thick hydrogen and helium atmosphere. Measurements of the transmission spectra of these planets offer the opportunity to resolve this degeneracy by directly constraining the scale heights and corresponding mean molecular weights of their atmospheres. We present Hubble Space Telescope near-infrared spectroscopy of two transits of the newly discovered transiting super-Earth HD 97658b. We use the Wide Field Camera 3's (WFC3) scanning mode to measure the wave length-dependent transit depth in 30 individual bandpasses. Our averaged differential transmission spectrum has a median 1sigma uncertainty of 23 ppm in individual bins, making this the most precise observation of an exoplanetary transmission spectrum obtained with WFC3 to date. Our data are inconsistent with a cloud-free solar metallicity atmosphere at the 10sigma level. They are consistent at the 0.4sigma level with a flat line model, as well as effectively flat models corresponding to a metal-rich atmosphere or a solar metallicity atmosphere with a cloud or haze layer located at pressures of 10 mbar or higher.
Abstract
We conducted interferometric observations with the CHARA Array of transiting super-Earth host HD 97658 and measured its limb-darkened angular diameter to be
θ
LD
= 0.314 ± 0.004 mas. The ...combination of the angular diameter with the Gaia EDR3 parallax value with zero-point correction (
π
= 46.412 ± 0.022 mas,
d
=21.546 ± 0.011 pc) yields a physical radius of
R
⋆
= 0.728 ± 0.008
R
⊙
. We also measured the bolometric flux of the star to be
F
bol
= 2.42 ± 0.05 × 10
−8
erg s
−1
cm
−2
, which, together with angular size, allows a measurement of the effective temperature
T
eff
= 5212 ± 43 K. Our directly determined physical stellar properties are in good agreement with previous estimates derived from spectroscopy. We used our measurements in combination with stellar evolutionary models and properties of the transit of HD 97658 b to determine the mass and age of HD 97658 as well as constrain the properties of the planet. Our results and our analysis of the TESS light curve on the planet (TOI-1821) corroborate previous studies of this system with tighter uncertainties.
New MOST† Photometry of the 55 Cancri System Dragomir, Diana; Matthews, Jaymie M.; Winn, Joshua N. ...
Proceedings of the International Astronomical Union,
08/2012, Letnik:
8, Številka:
S293
Journal Article
Recenzirano
Odprti dostop
Since the discovery of its transiting nature, the super-Earth 55 Cnc e has become one of the most enthusiastically studied exoplanets, having been observed spectroscopically and photometrically, in ...the ultraviolet, optical and infrared regimes. To this rapidly growing data set, we contribute 42 days of new, nearly continuous MOST photometry of the 55 Cnc system. Our analysis of these observations together with the discovery photometry obtained in 2011 allows us to determine the planetary radius (1.990+0.084−0.080) and orbital period (0.7365417+0.0000025−0.0000028) of 55 Cnc e with unprecedented precision. We also followed up on the out-of-transit phase variation first observed in the 2011 photometry, and set an upper limit on the depth of the planet's secondary eclipse, leading to an upper limit on its geometric albedo of 0.6.
Young exoplanets are snapshots of the planetary evolution process. Planets that orbit stars in young associations are particularly important because the age of the planetary system is well ...constrained. We present the discovery of a transiting planet larger than Neptune but smaller than Saturn in the 45 Myr Tucana-Horologium young moving group. The host star is a visual binary, and our follow-up observations demonstrate that the planet orbits the G6V primary component, DS Tuc A (HD 222259A, TIC 410214986). We first identified transits using photometry from the Transiting Exoplanet Survey Satellite (TESS; alerted as TOI 200.01). We validated the planet and improved the stellar parameters using a suite of new and archival data, including spectra from Southern Astrophysical Research/Goodman, South African Extremely Large Telescope/High Resolution Spectrograph and Las Cumbres Observatories/Network of Robotic Echelle Spectrographs; transit photometry from Spitzer; and deep adaptive optics imaging from Gemini/Gemini Planet Imager. No additional stellar or planetary signals are seen in the data. We measured the planetary parameters by simultaneously modeling the photometry with a transit model and a Gaussian process to account for stellar variability. We determined that the planetary radius is 5.70 0.17 R⊕ and that the orbital period is 8.1 days. The inclination angles of the host star's spin axis, the planet's orbital axis, and the visual binary's orbital axis are aligned within 15° to within the uncertainties of the relevant data. DS Tuc Ab is bright enough (V = 8.5) for detailed characterization using radial velocities and transmission spectroscopy.
The article presents a case study dealing with two companies in Romania that have implemented social accountability management systems in accordance with the SA8000 standard and improved them over ...the course of almost a decade. The analysis is performed in the context of the need to formalize private sector approaches to corporate citizenship through CSR initiatives and frameworks. It involves a semi-structured interview in each of the companies and the use of the benchmarking tool to perform a comparison among them. The discussion is focused on identifying success factors conducive to each situation or overall, that could be disseminated as good practices to other companies interested in pursuing the same effort.
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