Serendipitous Discovery and Parallax of a Nearby L Dwarf

A field star serendipitously observed in a parallax program proved to have a proper motion of 562 mas/yr and a parallax of 82 +- 2 mas. The star is identified with 2MASS J07003664+3157266. A Keck LRIS spectrum shows its spectral type to be L3.5, as expected from its infrared and optical colors and absolute magnitude. This object had not been previously recognized as an L dwarf, perhaps because of crowding at its relatively low Galactic latitude (b = +15.8 degrees).Comment: PASP, in press. 8 pages incl.2 postscript figures, plus one jpeg figur

Dwarf Archives: A Compendium of M, L, and T Dwarf Data

Dwarf Archives is an online archive containing astrometric, photometric, and spectroscopic information for all known L and T dwarfs (over 650 objects), as well as a select sample of over 500 M dwarfs. In this paper, we describe the specific data available in the archive, the interface for searching through it and discuss plans for future updates

The Collapse of the Wien Tail in the Coldest Brown Dwarf? Hubble Space Telescope Near-Infrared Photometry of WISE J085510.83-071442.5

We present Hubble Space Telescope (HST) near-infrared photometry of the coldest known brown dwarf, WISE J085510.83$-$071442.5 (WISE 0855$-$0714). WISE 0855$-$0714 was observed with the Wide Field Camera 3 (WFC3) aboard HST using the F105W, F125W, and F160W filters, which approximate the $Y$, $J$, and $H$ near-infrared bands. WISE 0855$-$0714 is undetected at F105W with a corresponding 2$\sigma$ magnitude limit of $\sim$26.9. We marginally detect WISE 0855$-$0714 in the F125W images (S/N $\sim$4), with a measured magnitude of 26.41 $\pm$ 0.27, more than a magnitude fainter than the $J-$band magnitude reported by Faherty and coworkers. WISE J0855$-$0714 is clearly detected in the F160W band, with a magnitude of 23.90 $\pm$ 0.02, the first secure detection of WISE 0855$-$0714 in the near-infrared. Based on these data, we find that WISE 0855$-$0714 has extremely red F105W$-$F125W and F125W$-$F160W colors relative to other known Y dwarfs. We find that when compared to the models of Saumon et al. and Morley et al., the F105W$-$F125W and F125W$-$F160W colors of WISE 0855$-$0714 cannot be accounted for simultaneously. These colors likely indicate that we are seeing the collapse of flux on the Wien tail for this extremely cold object.Comment: Accepted for publication in ApJ Letter

Low-mass Tertiary Companions to Spectroscopic Binaries. I. Common Proper Motion Survey for Wide Companions Using 2MASS

We report the first results of a multi-epoch search for wide (separations greater than a few tens of AU), low-mass tertiary companions of a volume-limited sample of 118 known spectroscopic binaries within 30 pc of the Sun, using the Two Micron All Sky Survey Point Source Catalog and follow-up observations with the KPNO and CTIO 4 m telescopes. Note that this sample is not volume complete but volume limited, and, thus, there is incompleteness in our reported companion rates. We are sensitive to common proper motion companions with separations from roughly 200 AU to 10,000 AU (~10ˮ → ~ 10'). From 77 sources followed-up to date, we recover 11 previously known tertiaries, 3 previously known candidate tertiaries, of which 2 are spectroscopically confirmed and 1 rejected, and 3 new candidates, of which 2 are confirmed and 1 rejected. This yields an estimated wide tertiary fraction of 19.5^(+5.2)_(–3.7)%. This observed fraction is consistent with predictions set out in star formation simulations where the fraction of wide, low-mass companions to spectroscopic binaries is >10%

Investigation of Anaplasma marginale Seroprevalence in a Traditionally Managed Large California Beef Herd.

Recent observations by stakeholders suggested that ecosystem changes may be driving an increased incidence of bovine erythrocytic anaplasmosis, resulting in a reemerging cattle disease in California. The objective of this prospective cohort study was to estimate the incidence of Anaplasma marginale infection using seroconversion in a northern California beef cattle herd. A total of 143 Black Angus cattle (106 prebreeding heifers and 37 cows) were enrolled in the study. Serum samples were collected to determine Anaplasma marginale seroprevalence using a commercially available competitive enzyme-linked immunosorbent assay test kit. Repeat sampling was performed in seronegative animals to determine the incidence density rate from March through September (2013). Seroprevalence of heifers was significantly lower than that of cows at the beginning of the study (P < 0.001) but not at study completion (P = 0.075). Incidence density rate of Anaplasma marginale infection was 8.17 (95% confidence interval: 6.04, 10.81) cases per 1000 cow-days during the study period. Study cattle became Anaplasma marginale seropositive and likely carriers protected from severe clinical disease that might have occurred had they been first infected as mature adults. No evidence was found within this herd to suggest increased risk for clinical bovine erythrocytic anaplasmosis

Predicting the sound insulation of plywood panels when treated with decoupled mass loaded barriers

The addition of mass loaded barriers can be used to improve the sound transmission loss properties of lightweight panels. Decoupling of the mass layer from the panel is achieved using a layer of open celled foam. This treatment causes the panel system to exhibit sound transmission loss behaviour that is similar to conventional double leaf walls. The effects of altering the thickness of the decoupling foam layer, the surface density of the barrier, and the attachment between the treatment and the panel were assessed experimentally. Several analytical prediction methods were combined to develop a model for the transmission loss of the treated system. The material properties of the panel and treatment were measured using static and dynamic methods. These measured values were used in the prediction methods. The prediction methods yielded a range of agreements with the experimental results. The quality of agreement was found to depend on the thickness of the foam decoupling layer, the surface density of the barrier layer and most significantly the attachment method

The secondary transfer of gunshot residue: an experimental investigation carried out with SEM-EDX analysis

Gunshot residue (GSR) is produced when a firearm is discharged and is routinely used in the forensic reconstruction of incidents involving firearms. SEM-EDX with automated detection and analysis software was used to investigate the extent of GSR secondary transfer following the discharge of a firearm. A series of experiments, which mimicked real-world scenarios, was set up to explore these under-researched mechanisms. The findings demonstrate that relatively large amounts of GSR can be transferred to an individual immediately after the discharge of the firearm, through contact with the hands of the shooter or handling of the gun. While varying between runs, over 100 particles were transferred via a handshake in one instance, and it was found that even very large particles (60–100+ µm) were transferred from the shooter to the second individual via a handshake. The findings have implications for forensic investigations, including highlighting the need to sample from individuals who might have been involved in transfers and underscoring the importance of achieving accurate particle counts using the SEM-EDX method. Most importantly, the findings suggest that the presence of GSR (especially in small quantities) may not always indicate that a person discharged a firearm and that the possibility for misidentification of the shooter exists, as does the potential to distinguish shooters from those who have acquired GSR through secondary transfer. Further experiments employing automated SEM-EDX are suggested, which will add to our understanding of GSR transfer evidence and continue to improve the accuracy of interpretations which are presented in court. © 2013 The Authors. X-Ray Spectrometry published by John Wiley & Sons, Ltd

The sound insulation of single leaf finite size rectangular plywood panels with orthotropic frequency dependent bending stiffness

Current theories for predicting the sound insulation of orthotropic materials are limited to a small range of infinite panels. This paper presents a method that allows for the prediction of the sound insulation of a finite size orthotropic panel. This method uses an equation for the forced radiation impedance of a finite size rectangular panel. This approach produces an equation that has three nested integrals. The long numerical calculation times were reduced by using approximate formulas for the azimuthally averaged forced radiation impedance. This reduced the number of nested integrals from three to two. The resulting predictions are compared to results measured using two sample sizes of four different thicknesses of plywood and one sample size of another three different thicknesses of plywood. Plywood was used for all the tests because it is somewhat orthotropic. It was found during testing that the Young's moduli of the plywood were dependent on the frequency of excitation. The influence of the frequency dependent Young's moduli was then included in the prediction method. The experimental results were also compared with a simple isotropic prediction method

Keck Imaging of Binary L Dwarfs

We present Keck near-infrared imaging of three binary L dwarf systems, all of which are likely to be sub-stellar. Two are lithium dwarfs, and a third exhibits an L7 spectral type, making it the coolest binary known to date. All have component flux ratios near 1 and projected physical separations between 5 and 10 AU, assuming distances of 18 to 26 pc from recent measurements of trigonometric parallax. These surprisingly similar binaries represent the sole detections of companions in ten L dwarf systems which were analyzed in the preliminary phase of a much larger dual-epoch imaging survey. The detection rate prompts us to speculate that binary companions to L dwarfs are common, that similar-mass systems predominate, and that their distribution peaks at radial distances in accord both with M dwarf binaries and with the radial location of Jovian planets in our own solar system. To fully establish these conjectures against doubts raised by biases inherent in this small preliminary survey, however, will require quantitative analysis of a larger volume-limited sample which has been observed with high resolution and dynamic range.Comment: LaTex manuscript in 13 pages, 3 postscript figures, Accepted for publication in the Letters of the Astrophysical Journal; Postscript pre-print version available at: http://www.hep.upenn.edu/PORG/papers/koerner99a.p