2,471 research outputs found
On the Apparent Orbital Inclination Change of the Extrasolar Transiting Planet TrES-2b
On June 15, 2009 UT the transit of TrES-2b was detected using the University
of Arizona's 1.55 meter Kuiper Telescope with 2.0-2.5 millimag RMS accuracy in
the I-band. We find a central transit time of
HJD, an orbital period of days, and an
inclination angle of , which is consistent with our
re-fit of the original I-band light curve of O'Donovan et al. (2006) where we
find . We calculate an insignificant inclination
change of over the last 3 years, and as
such, our observations rule out, at the level, the apparent
change of orbital inclination to as
predicted by Mislis and Schmitt (2009) and Mislis et al. (2010) for our epoch.
Moreover, our analysis of a recently published Kepler Space Telescope light
curve (Gilliland et al. 2010) for TrES-2b finds an inclination of for a similar epoch. These Kepler results definitively
rule out change in as a function of time. Indeed, we detect no significant
changes in any of the orbital parameters of TrES-2b.Comment: 19 pages, 1 table, 7 figures. Re-submitted to ApJ, January 14, 201
A Tentative Detection of a Starspot During Consecutive Transits of an Extrasolar Planet from the Ground: No Evidence of a Double Transiting Planet System Around TrES-1
There have been numerous reports of anomalies during transits of the planet
TrES-1b. Recently, Rabus and coworkers' analysis of HST observations lead them
to claim brightening anomalies during transit might be caused by either a
second transiting planet or a cool starspot. Observations of two consecutive
transits are presented here from the University of Arizona's 61-inch Kuiper
Telescope on May 12 and May 15, 2008 UT. A 5.4 +/- 1.7 mmag (0.54 +/- 0.17%)
brightening anomaly was detected during the first half of the transit on May 12
and again in the second half of the transit on May 15th. We conclude that this
is a tentative detection of a r greater than or equal to 6 earth radii starspot
rotating on the surface of the star. We suggest that all evidence to date
suggest TrES-1 has a spotty surface and there is no need to introduce a second
transiting planet in this system to explain these anomalies. We are only able
to constrain the rotational period of the star to 40.2 +22.9 -14.6 days, due to
previous errors in measuring the alignment of the stellar spin axis with the
planetary orbital axis. This is consistent with the previously observed P_obs =
33.2 +22.3 -14.3 day period. We note that this technique could be applied to
other transiting systems for which starspots exist on the star in the transit
path of the planet in order to constrain the rotation rate of the star.
(abridged)Comment: 21 pages, 3 tables, 6 figures, Accepted to Ap
A New Planet Around an M Dwarf: Revealing a Correlation Between Exoplanets and Stellar Mass
We report precise Doppler measurements of GJ317 (M3.5V) that reveal the
presence of a planet with a minimum mass Msini = 1.2 Mjup in an eccentric,
692.9 day orbit. GJ317 is only the third M dwarf with a Doppler-detected Jovian
planet. The residuals to a single-Keplerian fit show evidence of a possible
second orbital companion. The inclusion of an additional Jupiter-mass planet (P
= 2700 days, Msini = 0.83 Mjup) improves the quality of fit significantly,
reducing the rms from 12.5 m/s to 6.32 m/s. A false-alarm test yields a 1.1%
probability that the curvature in the residuals of the single-planet fit is due
to random fluctuations, lending additional credibility to the two-planet model.
However, our data only marginally constrain a two-planet fit and further
monitoring is necessary to fully characterize the properties of the second
planet. To study the effect of stellar mass on Jovian planet occurrence we
combine our samples of M stars, Solar-mass dwarfs and intermediate-mass
subgiants. We find a positive correlation between stellar mass and the
occurrence rate of Jovian planets within 2.5 AU; the former A-type stars in our
sample are nearly 5 times more likely than the M dwarfs to harbor a giant
planet. Our analysis shows that the correlation between Jovian planet
occurrence and stellar mass remains even after accounting for the effects of
stellar metallicity.Comment: ApJ accepted, 27 pages, 6 figures, 3 table
A comparison of the static and dynamic properties of a semi-flexible polymer using lattice-Boltzmann and Brownian dynamics simulations
The aim of this paper is to compare results from lattice-Boltzmann and
Brownian dynamics simulations of linear chain molecules. We have systematically
varied the parameters that may affect the accuracy of the lattice-Boltzmann
simulations, including grid resolution, temperature, polymer mass, and fluid
viscosity. The effects of the periodic boundary conditions are minimized by an
analytic correction for the different long-range interactions in periodic and
unbounded systems. Lattice-Boltzmann results for the diffusion coefficient and
Rouse mode relaxation times were found to be insensitive to temperature, which
suggests that effects of hydrodynamic retardation are small. By increasing the
resolution of the lattice-Boltzmann grid with respect to the polymer size,
convergent results for the diffusion coefficient and relaxation times were
obtained; these results agree with Brownian dynamics to within 1--2%.Comment: Corrected LB reduced time step () in Fig. 1 and Table
A Revised Orbital Ephemeris for HAT-P-9b
We present here three transit observations of HAT-P-9b taken on 14 February
2010, 18 February 2010, and 05 April 2010 UT from the University of Arizona's
1.55 meter Kuiper telescope on Mt. Bigelow. Our transit light curves were
obtained in the I filter for all our observations, and underwent the same
reduction process. All three of our transits deviated significantly
(approximately 24 minutes earlier) from the ephemeris of Shporer et al. (2008).
However, due to the large time span between our observed transits and those of
Shporer et al. (2008), a 6.5 second (2 sigma) shift downwards in orbital period
from the value of Shporer et al. (2008) is sufficient to explain all available
transit data. We find a new period of 3.922814 +/- 0.000002 days for HAT-P-9b
with no evidence for significant nonlinearities in the transit period.Comment: 10 pages, 3 figure
A Complete Catalog of Swift GRB Spectra and Durations: Demise of a Physical Origin for Pre-Swift High-Energy Correlations
We calculate durations and spectral paramaters for 218 Swift bursts detected
by the BAT instrument between and including GRBs 041220 and 070509, including
77 events with measured redshifts. Incorporating prior knowledge into the
spectral fits, we are able to measure the characteristic spectral
peak energy and the isotropic equivalent energy
(1-- keV) for all events. This complete and rather extensive catalog,
analyzed with a unified methodology, allows us to address the persistence and
origin of high-energy correlations suggested in pre-Swift observations. We find
that the - correlation is present in the Swift
sample; however, the best-fit powerlaw relation is inconsistent with the
best-fit pre-Swift relation at >5 sigma significance. Moreover, it has a factor
>~ 2 larger intrinsic scatter, after accounting for large errors on . A large fraction of the Swift events are hard and subluminous
relative to (and inconsistent with) the pre-Swift relation, in agreement with
indications from BATSE GRBs without redshift. Moreover, we determine an
experimental threshold for the BAT detector and show how the -- correlation arises artificially due to partial
correlation with the threshold. We show that pre-Swift correlations found by
Amati et al.(2002), Yonetoku et al. (2004), Firmani et al.(2006) (and
independently by others) are likely unrelated to the physical properties of
GRBs and are likely useless for tests of cosmology. Also, an explanation of
these correlations in terms of a detector threshold provides a natural and
quantitative explanation for why short-duration GRBs and events at low redshift
tend to be outliers to the correlations.Comment: 25 pages, 9 figures, 2 tables, Accepted to Ap
Five Planets Orbiting 55 Cancri
We report 18 years of Doppler shift measurements of a nearby star, 55 Cancri,
that exhibit strong evidence for five orbiting planets. The four previously
reported planets are strongly confirmed here. A fifth planet is presented, with
an apparent orbital period of 260 days, placing it 0.78 AU from the star in the
large empty zone between two other planets. The velocity wobble amplitude of
4.9 \ms implies a minimum planet mass \msini = 45.7 \mearthe. The orbital
eccentricity is consistent with a circular orbit, but modest eccentricity
solutions give similar \chisq fits. All five planets reside in low eccentricity
orbits, four having eccentricities under 0.1. The outermost planet orbits 5.8
AU from the star and has a minimum mass, \msini = 3.8 \mjupe, making it more
massive than the inner four planets combined. Its orbital distance is the
largest for an exoplanet with a well defined orbit. The innermost planet has a
semi-major axis of only 0.038 AU and has a minimum mass, \msinie, of only 10.8
\mearthe, one of the lowest mass exoplanets known. The five known planets
within 6 AU define a {\em minimum mass protoplanetary nebula} to compare with
the classical minimum mass solar nebula. Numerical N-body simulations show this
system of five planets to be dynamically stable and show that the planets with
periods of 14.65 and 44.3 d are not in a mean-motion resonance. Millimagnitude
photometry during 11 years reveals no brightness variations at any of the
radial velocity periods, providing support for their interpretation as
planetary.Comment: accepted to Ap
Ocean acidification disrupts the orientation of postlarval Caribbean spiny lobsters
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gravinese, P. M., Page, H. N., Butler, C. B., Spadaro, A. J., Hewett, C., Considine, M., Lankes, D., & Fisher, S. Ocean acidification disrupts the orientation of postlarval Caribbean spiny lobsters. Scientific Reports, 10(1), (2020): 18092, doi:10.1038/s41598-020-75021-9.Anthropogenic inputs into coastal ecosystems are causing more frequent environmental fluctuations and reducing seawater pH. One such ecosystem is Florida Bay, an important nursery for the Caribbean spiny lobster, Panulirus argus. Although adult crustaceans are often resilient to reduced seawater pH, earlier ontogenetic stages can be physiologically limited in their tolerance to ocean acidification on shorter time scales. We used a Y-maze chamber to test whether reduced-pH seawater altered the orientation of spiny lobster pueruli toward chemical cues produced by Laurencia spp. macroalgae, a known settlement cue for the species. We tested the hypothesis that pueruli conditioned in reduced-pH seawater would be less responsive to Laurencia spp. chemical cues than pueruli in ambient-pH seawater by comparing the proportion of individuals that moved to the cue side of the chamber with the proportion that moved to the side with no cue. We also recorded the amount of time (sec) before a response was observed. Pueruli conditioned in reduced-pH seawater were less responsive and failed to select the Laurencia cue. Our results suggest that episodic acidification of coastal waters might limit the ability of pueruli to locate settlement habitats, increasing postsettlement mortality.We thank the Steinwachs Family Foundation, which provided funding that supported Gravinese’s postdoctoral fellowship at Mote Marine Laboratory and Aquarium. We also acknowledge the partial support provided by the St. Petersburg College Titan Achievement minigrant program. Page was supported by a Mote Marine Laboratory and Aquarium Postdoctoral Research Fellowship. Postlarval spiny lobsters were collected with a state-issued Special Activity License (SAL-17-1868G-SR). We also thank those who helped with animal collection throughout this work including in-kind support provided by E. Muller and the Mote CAOS facility, as well as E. Bartels and C. Walter of the Coral Reef Monitoring and Assessment Program at Mote Marine Laboratory and Aquarium, as well as other field personnel including: L. Toth, S. Perry, T. Parker, A. Fine, L. Humphrey, and many undergraduate interns. We also thank L. Toth, E. Ross, B. Sharp, C. Crowley, J. Butler, and B. Crowder for editorial comments
Grafting and Paladin Pic-21 for Nematode and Weed Management in Vegetable Production
Two years of field trials conducted in a Meloidogyne incognita-infested field evaluated grafting and Paladin Pic-21 (dimethyl disulfide:chloropicrin [DMDS:Pic] 79:21) for root-knot nematode and weed control in tomato and melon. Tomato rootstocks evaluated were; 'TX301', 'Multifort', and 'Aloha'. 'Florida 47' was the scion and the nongrafted control. A double crop of melon was planted into existing beds following tomato harvest. Melon rootstocks, C. metulifer and 'Tetsukabuto', were evaluated with nongrafted 'Athena' in year 1. In year 2, watermelon followed tomato with scion variety 'Tri-X Palomar' as the control and also grafted onto 'Emphasis' and 'Strongtosa' rootstocks. Four soil treatments were applied in fall both years under Canslit metalized film; Paladin Pic-21, methyl bromide:chloropicrin (MeBr:C33, 67:33), Midas (iodomethane:chloropicrin 50:50), and a herbicide-treated control. M.incognita J2 in soil were highest in herbicide control plots and nongrafted tomato. All soil treatments produced similar tomato growth,which was greater than the herbicide control. All treatments reduced M. incognita J2 in roots compared to the herbicide control. 'Multifort' rootstock produced the largest and healthiest roots; however, the number of M. incognita isolated from roots did not differ among the tomato rootstocks tested. Galling on tomato was highest in herbicide control plots and nongrafted plants. In melon, M.incognita J2 in soil did not differ among melon rootstocks, but numbers isolated from melon rootstocks increased in 'Tetsukabuto' compared with C. metuliferus. 'Tetsukabuto' were larger root systems than nongrafted 'Athena'. All fumigants provided protection for all melon rootstocks against galling by M.incognita compared to the herbicide control. Galling on C. metuliferus rootstock was less in all fumigant treatments compared with nongrafted 'Athena' and 'Tetsukabuto'. In watermelon, M. incognita in soil and roots did not differ among soil treatments or watermelon rootstocks, and yield was lower in both grafted rootstocks compared with the nongrafted control. All soil treatments increased average fruit weight of watermelon compared with the herbicide control, and provided effective weed control, keeping the most predominant weed, purple nutsedge (Cyperus rotundus L.), density at or below 1/m row. Grafting commercial scions onto M. incognita-resistant rootstocks has potential for nematode management combined with soil treatments or as a stand-alone component in crop production systems
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