Maternity colony of Northern Long-eared Myotis (\u3ci\u3eMyotis septentrionalis\u3c/i\u3e) in a human-made structure in Nebraska

The Northern Long-eared Myotis (Myotis septentrionalis) occurs across eastern North America, and its range extends west into the Great Plains of the United States. Summer roosts of M. septentrionalis in the Great Plains are not well documented. Herein we describe a maternity colony of M. septentrionalis using small, elevated structures (i.e., cabins) in southeastern Nebraska. Cabins were in a small parcel of upland deciduous forest about 1.6 km from the Missouri River. The maternity colony was observed roosting in a space between the outer and inner walls of three different cabins from 21 June to 8 October 2014. Counts of individuals using the cabins suggest that the colony started to disband after mid-August. Identifying and monitoring maternity roosts of M. septentrionalis in the Great Plains will be important to effectively manage this federally threatened species, especially as the fungus that causes white-nose syndrome spreads into the region

Maternity colony of Northern Long-eared Myotis (\u3ci\u3eMyotis septentrionalis\u3c/i\u3e) in a human-made structure in Nebraska

The Northern Long-eared Myotis (Myotis septentrionalis) occurs across eastern North America, and its range extends west into the Great Plains of the United States. Summer roosts of M. septentrionalis in the Great Plains are not well documented. Herein we describe a maternity colony of M. septentrionalis using small, elevated structures (i.e., cabins) in southeastern Nebraska. Cabins were in a small parcel of upland deciduous forest about 1.6 km from the Missouri River. The maternity colony was observed roosting in a space between the outer and inner walls of three different cabins from 21 June to 8 October 2014. Counts of individuals using the cabins suggest that the colony started to disband after mid-August. Identifying and monitoring maternity roosts of M. septentrionalis in the Great Plains will be important to effectively manage this federally threatened species, especially as the fungus that causes white-nose syndrome spreads into the region

Laboratory Spectra of CO2 Vibrational Modes in Planetary Ice Analogs

Laboratory spectra have shown that CO2 is a powerful diagnostic tool for analyzing infrared data from remote observations, as it has been detected on icy moons in the outer Solar System as well as dust grain surfaces in the interstellar medium (ISM). IR absorption band profiles of CO2 within ice mixtures containing H2O and CH3OH change with respect to temperature and mixture ratios. In this particular study, the CO2 asymmetric stretching mode near 4.3 m (2350 cm (exp-1)), overtone mode near 1.97 m (5080 cm (exp-1)), and the combination bands near 2.7 m (3700 cm (exp-1)), 2.8 m (3600 cm (exp-1)), and 2.02 m (4960 cm (exp -1)), are systematically observed in different mixtures with H2O and CH3OH in temperature ranges from 15K to 150 K. Additionally, some high-temperature deposits (T greater than 50 K) of H2O, CH3OH, and CO2 ice mixtures were performed. These data may then be used to interpret infrared observational data obtained from icy surfaces in the outer Solar System and beyond

The Radio Spectrum of TVLM513-46546: Constraints on the Coronal Properties of a Late M Dwarf

We explore the radio emission from the M9 dwarf, TVLM513-46546, at multiple radio frequencies, determining the flux spectrum of persistent radio emission, as well as constraining the levels of circular polarization. Detections at both 3.6 and 6 cm provide spectral index measurement $\alpha$ (where S$_{\nu} \propto \nu^{\alpha}$) of $-0.4\pm0.1$. A detection at 20 cm suggests that the spectral peak is between 1.4 and 5 GHz. The most stringent upper limits on circular polarization are at 3.6 and 6 cm, with $V/I <$15%. These characteristics agree well with those of typical parameters for early to mid M dwarfs, confirming that magnetic activity is present at levels comparable with those extrapolated from earlier M dwarfs. We apply analytic models to investigate the coronal properties under simple assumptions of dipole magnetic field geometry and radially varying nonthermal electron density distributions. Requiring the spectrum to be optically thin at frequencies higher than 5 GHz and reproducing the observed 3.6 cm fluxes constrains the magnetic field at the base to be less than about 500 G. There is no statistically significant periodicity in the 3.6 cm light curve, but it is consistent with low-level variability.Comment: 11 pages, 2 figures Accepted for publication in the Astrophysical Journa

A New View of Ridge Segmentation and Near-Axis Volcanism at the East Pacific Rise, 8˚–12˚N, from EM300 Multibeam Bathymetry

New, high-resolution bathymetry for the East Pacific Rise between 8˚N and 12˚N was collected over a6 km wide swath centered on the ridge axis using the 30 kHz Simrad EM300 multibeam system. Thecoverage area corresponds latitudinally to the designated Ridge2000 Integrated Studies Site (ISS) for fastspreading ridges. The EM300 data, gridded at 30 m latitude by 50 m longitude, represent a greater than 4Ximprovement in horizontal resolution over previously available multibeam data and a 2X improvement indepth resolution. The new bathymetry was used to update the locations and hierarchy of ridge offsets forthis area. Among the many applications for this data, it enables us to tabulate volcanoes half the size thatcould be previously detected. The distribution of near-axis volcanic cones \u3e25 m high suggests that thispopulation of small, near-axis cones results from low effusion rate eruptions of the ridge axis

Basaltic Lava Domes, Lava Lakes, and Volcanic Segmentation on the Southern East Pacific Rise

Meter-scale DSL-120 sonar mapping and coregistered Argo II photographic observations reveal changes in eruptive style that closely follow the third-order structural segmentation of the ridge axis on the southern East Pacific Rise, 17o11\u27-18o37\u27S. Near segment ends we observe abundant basaltic lava domes which average 20 rn in height and 200 rn in basal diameter and have pillow lava as the dominant lava morphology. The ubiquity of pillow lava suggests low effusion rate eruptions. The abundance of lava domes suggests that the fissure eruptions were of sufficient duration to focus and produce a line of volcanic edifices. Near segment centers we observe fewer but larger lava domes, voluminous drained and collapsed lava lakes, and smooth lobate and sheet lava flows with very little pillow lava. The abundance of sheet flows suggests that high effusion rate eruptions are common. Fewer lava domes and large lava lakes suggest that fissure eruptions do not focus to point sources. This pattern was observed on eight third-order ridge segments suggesting that a fundamental volcanic segmentation of the ridge occurs on this scale. The third-order segment boundaries also correlate with local maxima in the seismicaxial magmac hamber reflector depth throughout the study area and decreased across-axis width of the region of seismic layer 2A thickening along the one segment where sufficient cross-axis seismic lines exist. The geochemically defined magmatic segment boundaries in the study area match the locations of our volcanic segment boundaries, although rocks ampling density is not adequate to constrain the variation across all the third-order volcanic segments that we identify. These observations suggest that variation in the processes of crustal accretion along axis occurs at a length scale of tens of kilometers on superfast spreading (\u3e 140 km/Myr full rate) mid-ocean ridges

Radio Constraints on Activity in Young Brown Dwarfs

We report on searches for radio emission from three of the nearest known young brown dwarfs using the Very Large Array. We have obtained sensitive upper limits on 3.6cm emission from 2MASSW J1207334-393254, TWA~5B and SSSPM J1102-3431, all of which are likely members of the $\sim$8-Myr-old TW Hydrae association. We derive constraints on the magnetic field strength and the number density of accelerated electrons, under the assumption that young brown dwarf atmospheres are able to produce gyrosynchrotron emission, as seems to be indicated in older brown dwarfs. For the young brown dwarf TWA~5B, the ratio of its detected X-ray luminosity to the upper limit on radio luminosity places it within the expected range for young stars and older, active stars. Thus, its behavior is anomalous compared to older brown dwarfs, in which radio luminosity is substantially enhanced over the expected relationship. Our observations deepen the conundrum of magnetic activity in brown dwarfs, and suggest that a factor other than age is more important for determining radio emission in cool substellar objects.Comment: accepted, ApJL replaced earlier version: typo in astro-ph author fiel

Crustal Fissuring on the Crest of the Southern East Pacific Rise at 17˚15\u27-40\u27S

Fissure densities and widths have been mapped along the axial zone of the superfast spreading southern East Pacific Rise (EPR) at 17_150–400S with the near-bottom DSL-120 and Argo II imaging systems. We observe that the youngest lava flows (on a relative age scale) are sparsely fissured and that there is a cumulative increase in fissure abundance with time that produces a strong positive correlation between fissure density and relative age of lava flows. Average fissure widths were used to estimate fissure depths. In the 17_150–400S area, calculated fissure depths are estimated to extend below the seismic layer 2A/2B boundary, and fissures are widest/deepest where lava flows are youngest. We interpret these wide fissures in relatively young flows to be eruptive fissures. Relatively young lava flows combined with high average fissure widths south of 17_250S suggest that there may have been recent dike propagation along the ridge crest in this area. In comparison to the northern EPR at 9_–10_N the density of fissuring on the southern EPR is significantly higher, due in part to the higher occurrence of relatively older, more areally restricted pillow lava flows