scholarly journals ON THE OCCURRENCE RATE OF HOT JUPITERS IN DIFFERENT STELLAR ENVIRONMENTS

2015 ◽  
Vol 799 (2) ◽  
pp. 229 ◽  
Author(s):  
Ji Wang ◽  
Debra A. Fischer ◽  
Elliott P. Horch ◽  
Xu Huang
Keyword(s):  
Occurrence Rate ◽  
Hot Jupiters

scholarly journals Lack of close-in, massive planets of main-sequence A-type stars from Kepler

2019 ◽  
Vol 489 (2) ◽  
pp. 2069-2078 ◽  
Author(s):  
Silvia Sabotta ◽  
Petr Kabath ◽  
Judith Korth ◽  
Eike W Guenther ◽  
Daniel Dupkala ◽  
...  
Keyword(s):  
High Frequency ◽  
Main Sequence ◽  
Light Curves ◽  
Occurrence Rate ◽  
Intermediate Mass ◽  
Very High Frequency ◽  
Hot Jupiters ◽  
Intermediate Mass Stars ◽  
The Masses ◽  
Very High

ABSTRACT Some theories of planet formation and evolution predict that intermediate-mass stars host more hot Jupiters than Sun-like stars, others reach the conclusion that such objects are very rare. By determining the frequencies of those planets we can test those theories. Based on the analysis of Kepler light curves it has been suggested that about 8 per cent of the intermediate-mass stars could have a close-in substellar companion. This would indicate a very high frequency of such objects. Up to now, there was no satisfactory proof or test of this hypothesis. We studied a previously reported sample of 166 planet candidates around main-sequence A-type stars in the Kepler field. We selected six of them for which we obtained extensive long-term radial velocity measurements with the Alfred Jensch 2-m telescope in Tautenburg and the Perek 2-m telescope in Ondřejov. We derive upper limits of the masses of the planet candidates. We show that we are able to detect this kind of planet with our telescopes and their instrumentation using the example of MASCARA-1 b. With the transit finding pipeline Extrans we confirm that there is no single transit event from a Jupiter-like planet in the light curves of those 166 stars. We furthermore determine that the upper limit for the occurrence rate of close-in, massive planets for A-type stars in the Kepler sample is around 0.75 per cent. We argue that there is currently little evidence for a very high frequency of close-in, massive planets of intermediate-mass stars.

scholarly journals Formation of hot Jupiters through disk migration and evolving stellar tides

2019 ◽  
Vol 628 ◽  
pp. A42 ◽  
Author(s):  
René Heller
Keyword(s):  
Survival Rates ◽  
Orbital Stability ◽  
Protoplanetary Disk ◽  
Young Star ◽  
Occurrence Rate ◽  
Stellar Rotation ◽  
Hot Jupiters ◽  
Rotation Periods ◽  
Pile Up ◽  
Hot Jupiter

Since the discovery of Jupiter-sized planets in extremely close orbits around Sun-like stars, several mechanisms have been proposed to produce these “hot Jupiters”. Here we address their pile-up at 0.05 AU observed in stellar radial velocity surveys, their long-term orbital stability in the presence of stellar tides, and their occurrence rate of 1.2 ± 0.38% in one framework. We calculate the combined torques on the planet from the stellar dynamical tide and from the protoplanetary disk in the type-II migration regime. The disk is modeled as a 2D nonisothermal viscous disk parameterized to reproduce the minimum-mass solar nebula. We simulate an inner disk cavity at various radial positions near the star and simulate stellar rotation periods according to observations of young star clusters. The planet is on a circular orbit in the disk midplane and in the equatorial plane of the star. We show that the two torques can add up to zero beyond the corotation radius around young, solar-type stars and stop inward migration. Monte Carlo simulations with plausible variations of our nominal parameterization of the star-disk-planet model predict hot-Jupiter survival rates between about 3% (for an α disk viscosity of 10−1) and 15% (for α = 10−3) against consumption by the star. Once the protoplanetary disk has been fully accreted, the surviving hot Jupiters are pushed outward from their tidal migration barrier and pile up at about 0.05 AU, as we demonstrate using a numerical implementation of a stellar dynamical tide model coupled with stellar evolution tracks. Orbital decay is negligible on a one-billion-year timescale due to the contraction of highly dissipative convective envelopes in young Sun-like stars. We find that the higher pile-up efficiency around metal-rich stars can at least partly explain the observed positive correlation between stellar metallicity and hot-Jupiter occurrence rate. Combined with the observed hot-Jupiter occurrence rate, our results for the survival rate imply that ≲8% (α = 10−3) to ≲43% (α = 10−1) of sun-like stars initially encounter an inwardly migrating hot Jupiter. Our scenario reconciles models and observations of young spinning stars with the observed hot-Jupiter pile up and hot-Jupiter occurrence rates.

scholarly journals Cool Jupiters greatly outnumber their toasty siblings: occurrence rates from the Anglo-Australian Planet Search

2019 ◽  
Vol 492 (1) ◽  
pp. 377-383 ◽  
Author(s):  
Robert A Wittenmyer ◽  
Songhu Wang ◽  
Jonathan Horner ◽  
R P Butler ◽  
C G Tinney ◽  
...  
Keyword(s):  
Solar System ◽  
Radial Velocity ◽  
Planetary System ◽  
Planetary Systems ◽  
Giant Planets ◽  
Occurrence Rate ◽  
Hot Jupiters ◽  
The Past ◽  
Order Of Magnitude

ABSTRACT Our understanding of planetary systems different to our own has grown dramatically in the past 30 yr. However, our efforts to ascertain the degree to which the Solar system is abnormal or unique have been hindered by the observational biases inherent to the methods that have yielded the greatest exoplanet hauls. On the basis of such surveys, one might consider our planetary system highly unusual – but the reality is that we are only now beginning to uncover the true picture. In this work, we use the full 18-yr archive of data from the Anglo-Australian Planet Search to examine the abundance of ‘cool Jupiters’ – analogues to the Solar system’s giant planets, Jupiter and Saturn. We find that such planets are intrinsically far more common through the cosmos than their siblings, the hot Jupiters. We find that the occurrence rate of such ‘cool Jupiters’ is $6.73^{+2.09}_{-1.13}$ per cent, almost an order of magnitude higher than the occurrence of hot Jupiters (at $0.84^{+0.70}_{-0.20}$ per cent). We also find that the occurrence rate of giant planets is essentially constant beyond orbital distances of ∼1 au. Our results reinforce the importance of legacy radial velocity surveys for the understanding of the Solar system’s place in the cosmos.

scholarly journals Searching For Transiting Planets Around Halo Stars. ii. Constraining the Occurrence Rate of Hot Jupiters

2021 ◽  
Vol 162 (3) ◽  
pp. 85
Author(s):  
Kiersten M. Boley ◽  
Ji Wang ◽  
Joel C. Zinn ◽  
Karen A. Collins ◽  
Kevin I. Collins ◽  
...  
Keyword(s):  
Occurrence Rate ◽  
Hot Jupiters ◽  
Transiting Planets ◽  
Halo Stars

scholarly journals Data calibration for the MASCARA and bRing instruments

2018 ◽  
Vol 619 ◽  
pp. A154 ◽  
Author(s):  
G. J. J. Talens ◽  
E. R. Deul ◽  
R. Stuik ◽  
O. Burggraaff ◽  
A.-L. Lesage ◽  
...  
Keyword(s):  
Light Curves ◽  
Occurrence Rate ◽  
Hot Jupiters ◽  
La Palma ◽  
Knowing That ◽  
Calibration Methods ◽  
Calibration Algorithm ◽  
One Year ◽  
Transit Signals ◽  
Data Calibration

Aims. MASCARA and bRing are photometric surveys designed to detect variability caused by exoplanets in stars with mV < 8.4. Such variability signals are typically small and require an accurate calibration algorithm, tailored to the survey, in order to be detected. This paper presents the methods developed to calibrate the raw photometry of the MASCARA and bRing stations and characterizes the performance of the methods and instruments. Methods. For the primary calibration, a modified version of the coarse decorrelation algorithm is used, which corrects for the extinction due to the earth’s atmosphere, the camera transmission, and intrapixel variations. Residual trends are removed from the light curves of individual stars using empirical secondary calibration methods. In order to optimize these methods, as well as characterize the performance of the instruments, transit signals were injected in the data. Results. After optimal calibration an RMS scatter of 10 mmag at mV ~ 7.5 is achieved in the light curves. By injecting transit signals with periods between one and five days in the MASCARA data obtained by the La Palma station over the course of one year, we demonstrate that MASCARA La Palma is able to recover 84.0, 60.5 and 20.7% of signals with depths of 2, 1 and 0.5%, respectively, with a strong dependency on the observed declination, recovering 65.4% of all transit signals at δ > 0° versus 35.8% at δ < 0°. Using the full three years of data obtained by MASCARA La Palma to date, similar recovery rates are extended to periods up to ten days. We derive a preliminary occurrence rate for hot Jupiters around A-stars of >0.4%, knowing that many hot Jupiters are still overlooked. In the era of TESS, MASCARA and bRing will provide an interesting synergy for finding long-period (>13.5 days) transiting gas-giant planets around the brightest stars.

scholarly journals Two New HATNet Hot Jupiters around A Stars and the First Glimpse at the Occurrence Rate of Hot Jupiters from TESS

2019 ◽  
Vol 158 (4) ◽  
pp. 141 ◽  
Author(s):  
G. Zhou ◽  
C. X. Huang ◽  
G. Á. Bakos ◽  
J. D. Hartman ◽  
David W. Latham ◽  
...  
Keyword(s):  
Occurrence Rate ◽  
Hot Jupiters

Extended envelopes of hot Jupiters

2020 ◽  
Author(s):  
Dmitrii V. Bisikalo ◽  
Valerii I. Shematovich ◽  
Pavel V. Kaygorodov ◽  
Andrei G. Zhilkin
Keyword(s):  
Hot Jupiters

Repurposing N,N-Dimethylacetamide (DMA), a Pharmaceutical Excipient, as a Prototype Novel Anti-inflammatory Agent for the Prevention and/or Treatment of Preterm Birth

2018 ◽  
Vol 24 (9) ◽  
pp. 989-992 ◽  
Author(s):  
Samir Gorasiya ◽  
Juliet Mushi ◽  
Ryan Pekson ◽  
Sabesan Yoganathan ◽  
Sandra E. Reznik
Keyword(s):  
Preterm Birth ◽  
Ex Vivo ◽  
The United States ◽  
Occurrence Rate ◽  
Pharmaceutical Excipient ◽  
Ongoing Work ◽  
Exciting Line ◽  
Pregnant Mice

Background: Preterm birth (PTB), or birth that occurs before 37 weeks of gestation, accounts for the majority of perinatal morbidity and mortality. As of 2016, PTB has an occurrence rate of 9.6% in the United States and accounts for up to 18 percent of births worldwide. Inflammation has been identified as the most common cause of PTB, but effective pharmacotherapy has yet to be developed to prevent inflammation driven PTB. Our group has discovered that N,N-dimethylacetamide (DMA), a readily available solvent commonly used as a pharmaceutical excipient, rescues lipopolysaccharide (LPS)-induced timed pregnant mice from PTB. Methods: We have used in vivo, ex vivo and in vitro approaches to investigate this compound further. Results: Interestingly, we found that DMA suppresses cytokine secretion by inhibiting nuclear factor-kappa B (NF-κB). In ongoing work in this exciting line of investigation, we are currently investigating structural analogs of DMA, some of them novel, to optimize this approach focused on the inflammation associated with PTB. Conclusion: Successful development of pharmacotherapy for the prevention of PTB rests upon the pursuit of multiple strategies to solve this important clinical challenge.

scholarly journals Understanding the unimodal distributions of cancer occurrence rates: it takes two factors for a cancer to occur

2020 ◽  
Author(s):  
Shuang Qiu ◽  
Zheng An ◽  
Renbo Tan ◽  
Ping-an He ◽  
Jingjing Jing ◽  
...  
Keyword(s):  
Occurrence Rate ◽  
Cancer Drug ◽  
Proliferative Potential ◽  
Cancer Type ◽  
Cancer Occurrence ◽  
Important Relationship ◽  
Age Regression ◽  
Age Dependent ◽  
Two Factors ◽  
Realistic Possibility

Abstract Data from the SEER reports reveal that the occurrence rate of a cancer type generally follows a unimodal distribution over age, peaking at an age that is cancer-type specific and ranges from 30+ through 70+. Previous studies attribute such bell-shaped distributions to the reduced proliferative potential in senior years but fail to explain why some cancers have their occurrence peak at 30+ or 40+. We present a computational model to offer a new explanation to such distributions. The model uses two factors to explain the observed age-dependent cancer occurrence rates: cancer risk of an organ and the availability level of the growth signals in circulation needed by a cancer type, with the former increasing and the latter decreasing with age. Regression analyses were conducted of known occurrence rates against such factors for triple negative breast cancer, testicular cancer and cervical cancer; and all achieved highly tight fitting results, which were also consistent with clinical, gene-expression and cancer-drug data. These reveal a fundamentally important relationship: while cancer is driven by endogenous stressors, it requires sufficient levels of exogenous growth signals to happen, hence suggesting the realistic possibility for treating cancer via cleaning out the growth signals in circulation needed by a cancer.

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