6 research outputs found

    Three K2 campaigns yield rotation periods for 1013 stars in Praesepe

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    We use three campaigns of K2 observations to complete the census of rotation in low-mass members of the benchmark, ≈670 Myr old open cluster Praesepe. We measure new rotation periods (Prot) for 220≲1.3 M☉ Praesepe members and recovery periods for 97% (793/812) of the stars with a Prot in the literature. Of the 19 stars for which we do not recover a Prot, 17 were not observed by K2. As K2’s three Praesepe campaigns took place over the course of 3 yr, we test the stability of our measured Prot for stars observed in more than one campaign. We measure Prot consistent to within 10% for >95% of the 331 likely single stars with ≥2 high-quality observations; the median difference in Prot is 0.3%, with a standard deviation of 2%. Nearly all of the exceptions are stars with discrepant Prot measurements in Campaign 18, K2’s last, which was significantly shorter than the earlier two (≈50 days rather than ≈75 days). This suggests that, despite the evident morphological evolution we observe in the light curves of 38% of the stars, Prot measurements for low-mass stars in Praesepe are stable on timescales of several years. A Prot can therefore be taken to be representative even if measured only once

    KELT-25 b and KELT-26 b: A Hot Jupiter and a Substellar Companion Transiting Young A Stars Observed by TESS

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    We present the discoveries of KELT-25 b (TIC 65412605, TOI-626.01) and KELT-26 b (TIC 160708862, TOI-1337.01), two transiting companions orbiting relatively bright, early A stars. The transit signals were initially detected by the KELT survey and subsequently confirmed by Transiting Exoplanet Survey Satellite (TESS) photometry. KELT-25 b is on a 4.40 day orbit around the V = 9.66 star CD-24 5016 (Teff=8280-180+440 K, M ∗ = 2.18-0.11+0.12 M o˙), while KELT-26 b is on a 3.34 day orbit around the V = 9.95 star HD 134004 (Teff = 8640-240+500 K, M ∗ = 1.93-0.16+0.14 M o˙), which is likely an Am star. We have confirmed the substellar nature of both companions through detailed characterization of each system using ground-based and TESS photometry, radial velocity measurements, Doppler tomography, and high-resolution imaging. For KELT-25, we determine a companion radius of R P = 1.64-0.043+0.039 R J and a 3σ upper limit on the companion's mass of ∼64 M J. For KELT-26 b, we infer a planetary mass and radius of M P = 1.41-0.51+0.43MJ and R P = 1.94-0.058+0.060 R J. From Doppler tomographic observations, we find KELT-26 b to reside in a highly misaligned orbit. This conclusion is weakly corroborated by a subtle asymmetry in the transit light curve from the TESS data. KELT-25 b appears to be in a well-aligned, prograde orbit, and the system is likely a member of the cluster Theia 449

    Effects of diclofenac and dexamethasone on horse experimental endotoxemia Efeitos do diclofenaco e da dexametasona na endotoxemia experimental em eqüinos

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    Fifteen healthy Mangalarga horses, aged two to three years were used to evaluate the possible beneficial effects of dexamethasone and sodium diclofenac administration during experimental endotoxemia in horses. They were divided into three groups with five animals each: control (C), sodium diclofenac (SD) and dexamethasone (DM). All groups were given 0.1µg of Escherichia coli O55:B5 endotoxin/kg of body weight, intravenous, over 15 minutes, and one of the following preparations: group C - 20ml of 0.9% saline intravenous, 30 minutes before endoxin infusion; group SD - 2.2mg/kg, per os, 60 minutes before endotoxin infusion and group DM - 1.1 mg/kg, intravenous, 30 minutes before endotoxin infusion. No increase in rectal temperature was observed in the SD or DM treated groups. SD did not prevent the significant leukopenia, neutropenia and lymphopenia induced three hours after LPS injection, but DM attenuated these changes. No significant changes in plasma and peritoneal fluid total protein, inorganic phosphorus or glucose concentrations and in total nucleated cell count in peritoneal fluid were observed. SD was effective to prevent the fever and changes in intestinal borborygmi and DM blocked the cellular changes induced by experimental endotoxemia.<br>Quinze eqüinos machos, da raça Mangalarga, com idades entre dois e três anos, foram utilizados para se avaliar os possíveis efeitos clínicos benéficos da administração de dexametasona ou diclofenaco sódico durante a endotoxemia experimental em eqüinos. Os animais foram divididos em três grupos de cinco animais cada: controle (C), diclofenaco sódico (SD) e dexametasona (DM). Todos os grupos receberam 0,1µg/kg de lipopolissarídeo de Escherichia coli 055:B5, durante 15 minutos, por via intravenosa mais: grupo SD - 2,2mg/kg de SD, por via oral, 60 minutos antes da infusão da endotoxina; grupo DM - 1,1mg/kg, por via intravenosa, 30 minutos antes da endotoxina; grupo C - 20ml de NaCl 0,9%, por via intravenosa, 30 minutos antes da endotoxina. O SD não preveniu a leucopenia, neutropenia e linfopenia ocorridas três horas após a indução da endotoxemia, porém a DM atenuou essas alterações. As taxas de proteínas plasmática e peritoneal, a concentração de glicose e de fósforo inorgânico e a contagem de células nucleadas totais peritoneais mantiveram-se inalteradas. O diclofenaco foi eficaz na prevenção da febre e alterações nos borborigmos intestinais enquanto que a dexametasona bloqueou as alterações no número de células inflamatórias em relação ao grupo controle
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