199 research outputs found
Solving Linearized Equations of the -body Problem Using the Lie-integration Method
Several integration schemes exits to solve the equations of motion of the
-body problem. The Lie-integration method is based on the idea to solve
ordinary differential equations with Lie-series. In the 1980s this method was
applied for the -body problem by giving the recurrence formula for the
calculation of the Lie-terms. The aim of this works is to present the
recurrence formulae for the linearized equations of motion of -body systems.
We prove a lemma which greatly simplifies the derivation of the recurrence
formulae for the linearized equations if the recurrence formulae for the
equations of motions are known. The Lie-integrator is compared with other
well-known methods. The optimal step size and order of the Lie-integrator are
calculated. It is shown that a fine-tuned Lie-integrator can be 30%-40% faster
than other integration methods.Comment: accepted for publication in MNRAS (13 pages, 4 figures); see
http://cm.elte.hu/lie (cm.elte.hu/lie) for softwar
HAT-P-9b: A Low Density Planet Transiting a Moderately Faint F star
We report the discovery of a planet transiting a moderately faint (V=12.3
mag) late F star, with an orbital period of 3.92289 +/- 0.00004 days. From the
transit light curve and radial velocity measurements we determine that the
radius of the planet is R_p = 1.40 +/- 0.06 R_Jup and that the mass is M_p =
0.78 +/- 0.09 M_Jup. The density of the new planet, rho = 0.35 +/- 0.06 g
cm^{-3}, fits to the low-density tail of the currently known transiting
planets. We find that the center of transit is at T_c = 2454417.9077 +/- 0.0003
(HJD), and the total transit duration is 0.143 +/- 0.004 days. The host star
has M_s = 1.28 +/- 0.13 M_Sun and R_s = 1.32 +/- 0.07 R_Sun.Comment: Submitted to ApJ; V2: Replaced with accepted versio
The mass and density of the dwarf planet (225088) 2007 OR10
The satellite of (225088) 2007 OR10 was discovered on archival Hubble Space
Telescope images and along with new observations with the WFC3 camera in late
2017 we have been able to determine the orbit. The orbit's notable
eccentricity, e0.3, may be a consequence of an intrinsically eccentric
orbit and slow tidal evolution, but may also be caused by the Kozai mechanism.
Dynamical considerations also suggest that the moon is small, D 100
km. Based on the newly determined system mass of 1.75x10 kg, 2007 OR10
is the fifth most massive dwarf planet after Eris, Pluto, Haumea and Makemake.
The newly determined orbit has also been considered as an additional option in
our radiometric analysis, provided that the moon orbits in the equatorial plane
of the primary. Assuming a spherical shape for the primary this approach
provides a size of 123050 km, with a slight dependence on the satellite
orbit orientation and primary rotation rate chosen, and a bulk density of
1.750.07 g cm for the primary. A previous size estimate that
assumed an equator-on configuration (1535 km) would provide a
density of 0.92 g cm, unexpectedly low for a 1000
km-sized dwarf planet.Comment: Accepted for publication in Icaru
The chromatin-modifying protein HUB2 is involved in the regulation of lignin composition in xylem vessels
PIRIN2 (PRN2) was earlier reported to suppress syringyl (S)-type lignin accumulation of xylem vessels of Arabidopsis thaliana. In the present study, we report yeast two-hybrid results supporting the interaction of PRN2 with HISTONE MONOUBIQUITINATION2 (HUB2) in Arabidopsis. HUB2 has been previously implicated in several plant developmental processes, but not in lignification. Interaction between PRN2 and HUB2 was verified by β-galactosidase enzymatic and co-immunoprecipitation assays. HUB2 promoted the deposition of S-type lignin in the secondary cell walls of both stem and hypocotyl tissues, as analysed by pyrolysis-GC/MS. Chemical fingerprinting of individual xylem vessel cell walls by Raman and Fourier transform infrared microspectroscopy supported the function of HUB2 in lignin deposition. These results, together with a genetic analysis of the hub2 prn2 double mutant, support the antagonistic function of PRN2 and HUB2 in deposition of S-type lignin. Transcriptome analyses indicated the opposite regulation of the S-type lignin biosynthetic gene FERULATE-5-HYDROXYLASE1 by PRN2 and HUB2 as the underlying mechanism. PRN2 and HUB2 promoter activities co-localized in cells neighbouring the xylem vessel elements, suggesting that the S-type lignin-promoting function of HUB2 is antagonized by PRN2 for the benefit of the guaiacyl (G)-type lignin enrichment of the neighbouring xylem vessel elements
The Transit Light Curve (TLC) Project. I. Four Consecutive Transits of the Exoplanet XO-1b
We present RIz photometry of four consecutive transits of the newly
discovered exoplanet XO-1b. We improve upon the estimates of the transit
parameters, finding the planetary radius to be R_P = 1.184 +0.028/-0.018
R_Jupiter and the stellar radius to be R_S = 0.928 +0.018/-0.013 R_Sun,
assuming a stellar mass of M_S = 1.00 +/- 0.03 M_Sun. The uncertainties in the
planetary and stellar radii are dominated by the uncertainty in the stellar
mass. These uncertainties increase by a factor of 2-3 if a more conservative
uncertainty of 0.10 M_Sun is assumed for the stellar mass. Our estimate of the
planetary radius is smaller than that reported by McCullough et al. (2006) and
yields a mean density that is comparable to that of TrES-1 and HD 189733b. The
timings of the transits have an accuracy ranging from 0.2 to 2.5 minutes, and
are marginally consistent with a uniform period.Comment: 22 pages, 5 figures, 2 tables. Accepted for publication in Ap
A clinical feasibility study to evaluate the safety and efficacy of PEOT/PBT implants for human donor site filling during mosaicplasty
Mosaicplasty has become a well-accepted treatment modality for articular cartilage lesions in the knee. Postoperative bleeding remains potentially concerning. This study evaluates the porous poly(ethylene oxide)terephthalate/poly(butylene terephthalate) (PEOT/PBT) implants used for donor site filling. Empty donor sites were the controls. After 9 months, MRI, macroscopical and histological analysis were carried out. Treated defects did not cause postoperative bleeding. No adverse events or inflammatory response was observed. PEOT/PBT implants were well integrated. Empty controls occasionally showed protrusion of repair tissue at the defect margins. Surface stiffness was minimally improved compared to controls. Existing polymer fragments indicated considerable biodegradation. Histological evaluation of the filled donor sites revealed congruent fibrocartilaginous surface repair with proteoglycan-rich domains and subchondral cancellous bone formation with interspersed fibrous tissue in all implanted sites. The PEOT/PBT implants successfully reduce donor site morbidity and postoperative bleeding after mosaicplasty
Three is the magic number -- distance measurement of NGC 3147 using SN 2021hpr and its siblings
The nearby spiral galaxy NGC 3147 hosted three Type Ia supernovae (SNe Ia) in
the past decades, which have been subjects of intense follow-up observations.
Simultaneous analysis of their data provides a unique opportunity for testing
the different light curve fitting methods and distance estimations. The
detailed optical follow-up of SN 2021hpr allows us to revise the previous
distance estimations to NGC 3147, and compare the widely used light curve
fitting algorithms to each other. After the combination of the available and
newly published data of SN 2021hpr, its physical properties can be also
estimated with higher accuracy. We present and analyse new BVgriz and Swift
photometry of SN 2021hpr to constrain its general physical properties. Together
with its siblings, SNe 1997bq and 2008fv, we cross-compare the individual
distance estimates of these three SNe given by the SALT code, and also check
their consistency with the results from the MLCS2k2 method. The early spectral
series of SN 2021hpr are also fit with the radiative spectral code TARDIS in
order to verify the explosion properties and constrain the chemical
distribution of the outer ejecta. After combining the distance estimates for
the three SNe, the mean distance to their host galaxy, NGC 3127, is 42.5
1.0 Mpc, which matches with the distance inferred by the most up-to-date LC
fitters, SALT3 and BayeSN. We confirm that SN~2021hpr is a Branch-normal Type
Ia SN that ejected M from its progenitor white
dwarf, and synthesized M of radioactive Ni.Comment: 16 pages, 17 figures, 11 tables; accepted for publication in A&
Photometry of 10 Million Stars from the First Two Years of TESS Full Frame Images - Part II
We present light curves from a magnitude limited set of stars and other stationary luminous objects from the TESS Full Frame Images, as reduced by the MIT Quick Look Pipeline (QLP). Our light curves cover the full two-year TESS Primary Mission and include ∼14,770,000 and ∼9,600,000 individual light curve segments in the Southern and Northern ecliptic hemispheres, respectively. We describe the detrending techniques we used to create the light curves, and compare the noise properties with theoretical expectations. All of the QLP light curves are available at MAST as a High Level Science Product (HLSP) via doi:10.17909/t9-r086-e880 (https://archive.stsci.edu/hlsp/qlp). This is the largest collection of TESS photometry available to the public to date
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