Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
373
result(s) for
"Lopez, Eric D."
Sort by:
Superman : President Luthor
His fame bolstered after helping to rebuild Gotham City after an earthquake, billionaire Lex Luthor decides to run for the highest office in the land, the American presidency.
Book
HAT-P-26b
A correlation between giant-planet mass and atmospheric heavy elemental abundance was first noted in the past century from observations of planets in our own Solar System and has served as a cornerstone of planet-formation theory. Using data from the Hubble and Spitzer Space Telescopes from 0.5 to 5 micrometers, we conducted a detailed atmospheric study of the transiting Neptune-mass exoplanet HAT-P-26b. We detected prominent H₂O absorption bands with a maximum base-to-peak amplitude of 525 parts per million in the transmission spectrum. Using the water abundance as a proxy for metallicity, we measured HAT-P-26b’s atmospheric heavy element content (
4.8
−
4.0
+
21.5
times solar). This likely indicates that HAT-P-26b’s atmosphere is primordial and obtained its gaseous envelope late in its disk lifetime, with little contamination from metal-rich planetesimals.
Journal Article
Kepler-36: A Pair of Planets with Neighboring Orbits and Dissimilar Densities
In the solar system, the planets' compositions vary with orbital distance, with rocky planets in close orbits and lower-density gas giants in wider orbits. The detection of close-in giant planets around other stars was the first clue that this pattern is not universal and that planets' orbits can change substantially after their formation. Here, we report another violation of the orbit-composition pattern: two planets orbiting the same star with orbital distances differing by only 10% and densities differing by a factor of 8. One planet is likely a rocky \"super-Earth,\" whereas the other is more akin to Neptune. These planets are 20 times more closely spaced and have a larger density contrast than any adjacent pair of planets in the solar system.
Journal Article
Author Correction: An ultrahot Neptune in the Neptune desert
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Journal Article
A sub-Mercury-sized exoplanet
Stellar data from the Kepler spacecraft are used to infer the existence of a sub-Mercury-sized exoplanet, the smallest yet discovered, in orbit around a Sun-like star.
Mercury-like exoplanets in Kepler's sights
When the Kepler spacecraft was launched in 2009 its brief was to search for rocky planets around Sun-like host stars in our Galaxy. Many of the hundreds of known exoplanets are large 'hot Jupiters' close-in to their stars. Last year it became possible to detect Earth-sized exoplanets, and now comes the discovery of a rocky planet significantly smaller than Mercury. Kepler-37b is orbiting the Sun-like star Kepler-37 in a system with at least two other planets. It is similar to our Moon in size and is likely to resemble Mercury: rocky, no atmosphere and no water.
Since the discovery of the first exoplanets
1
,
2
, it has been known that other planetary systems can look quite unlike our own
3
. Until fairly recently, we have been able to probe only the upper range of the planet size distribution
4
,
5
, and, since last year, to detect planets that are the size of Earth
6
or somewhat smaller
7
. Hitherto, no planets have been found that are smaller than those we see in the Solar System. Here we report a planet significantly smaller than Mercury
8
. This tiny planet is the innermost of three that orbit the Sun-like host star, which we have designated Kepler-37. Owing to its extremely small size, similar to that of the Moon, and highly irradiated surface, the planet, Kepler-37b, is probably rocky with no atmosphere or water, similar to Mercury.
Journal Article
An ultrahot Neptune in the Neptune desert
About 1 out of 200 Sun-like stars has a planet with an orbital period shorter than one day: an ultrashort-period planet
1
,
2
. All of the previously known ultrashort-period planets are either hot Jupiters, with sizes above 10 Earth radii (
R
⊕
), or apparently rocky planets smaller than 2
R
⊕
. Such lack of planets of intermediate size (the ‘hot Neptune desert’) has been interpreted as the inability of low-mass planets to retain any hydrogen/helium (H/He) envelope in the face of strong stellar irradiation. Here we report the discovery of an ultrashort-period planet with a radius of 4.6
R
⊕
and a mass of 29
M
⊕
, firmly in the hot Neptune desert. Data from the Transiting Exoplanet Survey Satellite
3
revealed transits of the bright Sun-like star LTT 9779 every 0.79 days. The planet’s mean density is similar to that of Neptune, and according to thermal evolution models, it has a H/He-rich envelope constituting 9.0
−
2.9
+
2.7
% of the total mass. With an equilibrium temperature around 2,000 K, it is unclear how this ‘ultrahot Neptune’ managed to retain such an envelope. Follow-up observations of the planet’s atmosphere to better understand its origin and physical nature will be facilitated by the star’s brightness (
V
mag
= 9.8).
LTT 9779 b is Neptune-sized planet rotating around its star with a period of 0.79 days and an equilibrium temperature of 2,000 K. It is not clear how it retained its atmospheric envelope, which contains ~10% of H/He, as it should have been photoevaporated by now.
Journal Article
Erratum: A sub-Mercury-sized exoplanet
Nature 494, 452–454 (2013); doi:10.1038/nature11914 In this Letter, the Centro de Astrobiología affiliation (number 11, associated with authors David Barrado and Jorge Lillo-Box) was listed incorrectly; the correct address is: ‘Departamento Astrofísica, Centro de Astrobiología (INTA-CSIC), ESAC campus, PO Box 78, E-28691 Villanueva de la Cañada, Spain’.
Journal Article
Removal of Hot Saturns in Mass-Radius Plane by Runaway Mass Loss
The hot Saturn population exhibits a boundary in mass-radius space, such that no planets are observed at a density less than \\(\\sim\\)0.1 g cm\\(^{-3}\\). Yet, planet interior structure models can readily construct such objects as the natural result of radius inflation. Here, we investigate the role XUV-driven mass-loss plays in sculpting the density boundary by constructing interior structure models that include radius inflation, photoevaporative mass loss and a simple prescription of Roche lobe overflow. We demonstrate that planets puffier than \\(\\sim\\)0.1 g cm\\(^{-3}\\) experience a runaway mass loss caused by adiabatic radius expansion as the gas layer is stripped away, providing a good explanation of the observed edge in mass-radius space. The process is also visible in the radius-period and mass-period spaces, though smaller, high-bulk-metallicity planets can still survive at short periods, preserving a partial record of the population distribution at formation.
Paper
Born Dry in the Photo-Evaporation Desert: Kepler's Ultra-Short-Period Planets Formed Water-Poor
Recent surveys have uncovered an exciting new population of ultra-short-period (USP) planets with orbital periods less than a day. These planets typically have radii <1.5 Earth radii, indicating that they likely have rocky compositions. This stands in contrast to the overall distribution of planets out to ~100 days, which is dominated by low-density sub-Neptunes above 2 Earth radii, which must have gaseous envelopes to explain their size. However, on ultra-short-period orbits, planets are bombarded by intense levels of photo-ionizing radiation and consequently gaseous sub-Neptunes are extremely vulnerable to losing their envelopes to atmospheric photo-evaporation. Using models of planet evolution, I show that the rocky USP planets can easily be produced as the evaporated remnants of sub-Neptunes with H/He envelopes and that we can therefore understand the observed dearth of USP sub-Neptunes as a natural consequence of photo-evaporation. Critically however, planets on USP orbits could often retain their envelopes if they formed with very high-metallicity water dominated envelopes. Such water-rich planets would commonly be >2 Earth radii today, which is inconsistent with the observed evaporation desert, indicating that most USP planets likely formed from water-poor material within the snow-line. Finally, I examine the special case of 55 Cancri e and its possible composition in the light of recent observations, and discuss the prospects for further characterizing this population with future observations.
Paper
Re-inflation of warm and hot Jupiters
Understanding the anomalous radii of many transiting hot gas giant planets is a fundamental problem of planetary science. Recent detections of re-inflated warm Jupiters orbiting post-main-sequence stars and the re-inflation of hot Jupiters while their host stars evolve on the main-sequence may help constrain models for the anomalous radii of hot Jupiters. In this work, we present evolution models studying the re-inflation of gas giants to determine how varying the depth and intensity of deposited heating affects both main-sequence re-inflation of hot Jupiters and post-main-sequence re-inflation of warm Jupiters. We find that deeper heating is required to re-inflate hot Jupiters than is needed to suppress their cooling, and that the timescale of re-inflation decreases with increasing heating rate and depth. We find a strong degeneracy between heating rate and depth, with either strong shallow heating or weak deep heating providing an explanation for main-sequence re-inflation of hot Jupiters. This degeneracy between heating rate and depth can be broken in the case of post-main-sequence re-inflation of warm Jupiters, as the inflation must be rapid to occur within post-main-sequence evolution timescales. We also show that the dependence of heating rate on incident stellar flux inferred from the sample of hot Jupiters can explain re-inflation of both warm and hot Jupiters. TESS will obtain a large sample of warm Jupiters orbiting post-main-sequence stars, which will help to constrain the mechanism(s) causing the anomalous radii of gas giant planets.
Paper