Water vapor in the lower stratosphere measured from aircraft flight

Water vapor in the lower stratosphere was measured in situ by two aluminum oxide hygrometers mounted on the nose of an RB57 aircraft. Data were taken nearly continuously from January to May 1974 from an altitude of approximately 11 km to 19 km as the aircraft flew between 70 deg N and 50 deg S over the land areas in the Western Hemisphere. Pseudomeridional cross sections of water vapor and temperature are derived from the flight data and show mixing ratios predominantly between 2 and 4 micron gm/gm with an extreme range of 1 to 8 micron gm/gm. Measurement precision is estimated by comparing the simultaneously measured values from the two flight hygrometer systems. Accuracy is estimated to be about + or - 40 percent at 19 km. A height-averaged latitudinal cross section of water vapor shows symmetry of wet and dry zones

A low-mass stellar companion of the planet host star HD75289

We report on the detection of a new low-mass stellar companion of HD75289, a G0V star that harbors one known radial-velocity planet (Udry et al. 2000). Comparing an image of 2MASS with an image we obtained with SofI at the ESO 3.58m NTT three years later, we detected a co-moving companion located 21.465+-0.023arcsecs (621+-10AU at 29pc) east of HD75289. A second SofI image taken 10 months later confirmed the common proper motion of HD75289B with its host star. The infrared spectrum and colors of the companion are consistent with an M2 to M5 main-sequence star at the distance of HD75289. No further (sub)stellar companion down to H = 19mag could be detected. With the SofI detection limit we can rule out additional stellar companions beyond 140AU and substellar companions with masses m > 0.050Msun from 400AU up to 2000AU.Comment: accepted in A&

ROTSE observations of the young cluster IC 348

CCD observations of stars in the young cluster IC 348 were obtained from 2004 August to 2005 January with a 0.45 m ROTSEIIId robotic reflecting telescope at the Turkish National Observatory site, Bakirlitepe, Turkey. The timing analysis of selected stars whose X-Ray counterpart were detected by Chandra X-Ray Observatory were studied. The time series of stars were searched for rotational periodicity by using different period search methods. 35 stars were found to be periodic with periods ranging from 0.74 to 32.3 days. Eighteen of the 35 periodic stars were new detections. Four of the new detections were CTTSs and the others were WTTSs and G type (or unknown spectral class) stars. In this study, we confirmed the stability of rotation periods of TTauri stars. The periods obtained by Cohen et al. and us were different by 1%. We also confirmed the 3.24 h pulsation period of H254 which is a delta Scuti type star as noted by Ripepi et al. but the other periods detected by them were not found. We examined correlation between X-ray luminosity and rotational period of our sample of TTSs. There is a decline in the rotational period with X-ray luminosity for late type TTSs.Comment: 15 pages, 14 figures, accepted for publication in Astronomical Journa

Gust penetration loads and elastic vehicle response for Saturn 5 launch vehicles

Analysis of gust penetration loads and associated elastic vehicle response of Saturn 5 launch vehicles AS-505 through AS-508 penetrating sinusoidal gust

Do Steller’s jays respond to human providers?

For millennia, humans and wildlife coevolved in a myriad of landscapes influencing each other through social interactions. Humans may be providing non-verbal signals in their facial features with gaze and head orientation that are perceived by non-human animals. The ability to follow human eye gaze and head orientation could enable non-human animals to access valuable resources, for example, birds provided with supplemental food. Few studies have quantified how closely birds in the wild watch and respond to ‘familiar’ humans who regularly provide food. From 2015-2019, Steller’s jays (Cyanocitta stelleri) in Arcata, California were fed shelled peanuts and observed approaching human providers. In 2021, I investigated how free-ranging color-marked Steller’s jays recognized and responded to five human social cues displayed, first, by a familiar human food provider, and second, by an unfamiliar human food provider. Steller’s jays responded differently to the first and second human providers, but not to the cues they displayed (eye gaze and posture). The lack of response to human social cues could be broad-scale habituation of humans in the study area. Habituated Steller’s jays exposed to regular supplemental feeding may recognize human faces and social cues, and may not be deterred by human gaze, whereas less-habituated individuals may be more wary of human gaze direction. Understanding how wild animals perceive human behavior at an individual and population level may minimize human-wildlife disturbance and inform conservation practices

An evaluation of aft-end ignition for solid propellant rocket motors

Performance evaluation of solid propellant rocket motor ignition to determine igniter design and parameters to avoid overpressurizatio