24 research outputs found
TKS X: Confirmation of TOI-1444b and a Comparative Analysis of the Ultra-short-period Planets with Hot Neptunes
We report the discovery of TOI-1444b, a 1.4- super-Earth on a
0.47-day orbit around a Sun-like star discovered by {\it TESS}. Precise radial
velocities from Keck/HIRES confirmed the planet and constrained the mass to be
. The RV dataset also indicates a possible
non-transiting, 16-day planet (). We report a tentative
detection of phase curve variation and secondary eclipse of TOI-1444b in the
{\it TESS} bandpass. TOI-1444b joins the growing sample of 17
ultra-short-period planets with well-measured masses and sizes, most of which
are compatible with an Earth-like composition. We take this opportunity to
examine the expanding sample of ultra-short-period planets () and
contrast them with the newly discovered sub-day ultra-hot Neptunes
(, TOI-849 b, LTT9779 b and K2-100). We find that
1) USPs have predominately Earth-like compositions with inferred iron core mass
fractions of 0.320.04; and have masses below the threshold of runaway
accretion (), while ultra-hot Neptunes are above the threshold
and have H/He or other volatile envelope. 2) USPs are almost always found in
multi-planet system consistent with a secular interaction formation scenario;
ultra-hot Neptunes (1 day) tend to be ``lonely' similar
to longer-period hot Neptunes(1-10 days) and hot Jupiters. 3) USPs
occur around solar-metallicity stars while hot Neptunes prefer higher
metallicity hosts. 4) In all these respects, the ultra-hot Neptunes show more
resemblance to hot Jupiters than the smaller USP planets, although ultra-hot
Neptunes are rarer than both USP and hot Jupiters by 1-2 orders of magnitude.Comment: Accepted too AJ. 12 Figures, 4 table
Affectus Hispaniae en la historiografía del Alto Imperio
This paper analyses texts written by Greek and Latin High Empire historians dealing with Hispania. Some of the authors have a very positive view (Florus, Iustinus, Appian) while others are clearly negative (Veleius Paterculus, Valerius Maximus) though most of them show little interest, indifference or variety of opinions. When there is interest in the region or praise, it is because the author comes from Hispania or he is trying to please an emperor born in Hispania, but it could also be due to a universal conception of history revealing a critical attitude towards Roman imperialism, as in Appian. The praise found in Iustinus’s epitome should be attributed to the author of the epitome rather than to Pompeius Trogus. This can be taken as evidence for situating Iustinus’s life and work in the 2nd century A.D. Loathing of Hispania seems to have its origins in conservative, ‘optimate’ nationalist circles, who perceive the province as the ‘popular’ region that acclaimed and welcomed ‘seditious’ individuals such as Tiberius Gracchus and Sertorius.Se estudian en este trabajo los textos de historiadores del Alto Imperio, latinos y griegos, que tratan sobre Hispania. En algunos autores encontramos una visión muy positiva (Floro, Justino, Apiano) y en otros claramente negativa (Veleyo Patérculo, Valerio Máximo), aunque en la mayoría de los casos hay escasa atención, indiferencia o diversidad de opiniones. El interés por la región y los elogios pueden estar motivados por el origen hispánico del autor o su voluntad de agradar a algún emperador oriundo de Hispania, pero también por una concepción universal de la historia que denota en ocasiones una posición crítica con el imperialismo romano, como es el caso de Apiano. La alabanza que hallamos en el epítome de Justino creemos que debe atribuirse más al epitomador que a Pompeyo Trogo, lo que apoyaría una datación temprana de la vida y la obra de Justino (s. II d.C.). La aversión hacia Hispania parece haber surgido en medios conservadores, “optimates” nacionalistas, que ven la provincia como el territorio “popular”, que encumbró y acogió a “sediciosos” como Tiberio Graco y Sertorio
The TESS-Keck Survey II: An Ultra-Short Period Rocky Planet and its Siblings Transiting the Galactic Thick-Disk Star TOI-561
We report the discovery of TOI-561, a multi-planet system in the galactic
thick disk that contains a rocky, ultra-short period planet (USP). This bright
() star hosts three small transiting planets identified in photometry
from the NASA TESS mission: TOI-561 b (TOI-561.02, P=0.44 days, ), c (TOI-561.01, P=10.8 days,
), and d (TOI-561.03, P=16.3 days,
). The star is chemically ([Fe/H],
[/H]) and kinematically consistent with the galactic
thick disk population, making TOI-561 one of the oldest (Gyr) and
most metal-poor planetary systems discovered yet. We dynamically confirm
planets b and c with radial velocities from the W. M. Keck Observatory High
Resolution Echelle Spectrometer. Planet b has a mass and density of
and gcm, consistent with
a rocky composition. Its lower-than-average density is consistent with an
iron-poor composition, although an Earth-like iron-to-silicates ratio is not
ruled out. Planet c is and gcm,
consistent with an interior rocky core overlaid with a low-mass volatile
envelope. Several attributes of the photometry for planet d (which we did not
detect dynamically) complicate the analysis, but we vet the planet with
high-contrast imaging, ground-based photometric follow-up and radial
velocities. TOI-561 b is the first rocky world around a galactic thick-disk
star confirmed with radial velocities and one of the best rocky planets for
thermal emission studies.Comment: Accepted at The Astronomical Journal; 25 pages, 10 figure
A Super-Earth and Sub-Neptune Transiting the Late-type M Dwarf LP 791-18
Planets occur most frequently around cool dwarfs, but only a handful of specific examples are known to orbit the latest-type M stars. Using TESS photometry, we report the discovery of two planets transiting the low-mass star called LP 791-18 (identified by TESS as TOI 736). This star has spectral type M6V, effective temperature 2960 K, and radius 0.17 R o, making it the third-coolest star known to host planets. The two planets straddle the radius gap seen for smaller exoplanets; they include a 1.1R ⊕ planet on a 0.95 day orbit and a 2.3R ⊕ planet on a 5 day orbit. Because the host star is small the decrease in light during these planets' transits is fairly large (0.4% and 1.7%). This has allowed us to detect both planets' transits from ground-based photometry, refining their radii and orbital ephemerides. In the future, radial velocity observations and transmission spectroscopy can both probe these planets' bulk interior and atmospheric compositions, and additional photometric monitoring would be sensitive to even smaller transiting planets
The Edifying Discourses of Adam Smith: Focalism, Commerce, and Serving the Common Good
Smith’s discourses aim to encourage mores, practices, and public policies in service to the common good, or that which a universally benevolent spectator would approve of. The Wealth of Nations illustrates how in pursuing our own happiness within the bounds of prudence and commutative justice we may be said, literally or metaphorically, to cooperate with God in furthering the happiness of humankind. The Theory of Moral Sentiments elaborates an ethic, here called “focalism,” that instructs us to proportion our beneficent efforts to our knowledge and ability. The relationship between political economy and focalism is bidirectionally reinforcing. In one direction, the ethic of focalism contributes to the moral authorization of self-love, thereby invigorating and dignifying honest commercial activities. In the other direction, the insights of political economy reinforce the ethic of focalism by elaborating how through prudent commerce and focal beneficence we cooperate, even if only metaphorically, in a grand social enterprise