898 research outputs found
Identification of WISE J000100.45+065259.6 as an M8.5+T5 Spectral Binary Candidate
[not part of RNAAS note] We report the discovery of WISE J000100.45+065259.6
as a very low mass star/brown dwarf spectral binary candidate, on the basis of
low resolution near-infrared spectroscopy obtained with IRTF/SpeX.
Decomposition of the spectrum indicates component types of M8.5+T5 with a
predicted = 3.5. As the majority of confirmed spectral binary
candidates to date are very closely-separated systems ( 3 AU;
15~yr), this source may provide mass measurements across the
hydrogen burning limit within the decade.Comment: 3 pages, 1 figure, accepted to Research Notes of the AA
Magnetic inflation and stellar mass. V. Intensification and saturation of M-dwarf absorption lines with Rossby number
In young Sun-like stars and field M-dwarf stars, chromospheric and coronal magnetic activity indicators such as Hα, X-ray, and radio emission are known to saturate with low Rossby number (Ro lesssim 0.1), defined as the ratio of rotation period to convective turnover time. The mechanism for the saturation is unclear. In this paper, we use photospheric Ti i and Ca i absorption lines in the Y band to investigate magnetic field strength in M dwarfs for Rossby numbers between 0.01 and 1.0. The equivalent widths of the lines are magnetically enhanced by photospheric spots, a global field, or a combination of the two. The equivalent widths behave qualitatively similar to the chromospheric and coronal indicators: we see increasing equivalent widths (increasing absorption) with decreasing Ro and saturation of the equivalent widths for Ro lesssim 0.1. The majority of M dwarfs in this study are fully convective. The results add to mounting evidence that the magnetic saturation mechanism occurs at or beneath the stellar photosphere.Published versio
Thank you to all our manuscript reviewers in 2015
The editors of Hereditary Cancer in Clinical Practice would like to thank all our reviewers who have contributed to the journal in 2015. Without the participation of skilful reviewers, no academic journal could succeed, and we are grateful to the committed individuals who have given their time and expertise to the peer review of manuscripts for Hereditary Cancer in Clinical Practice. We look forward to your continued support in 2016
Dynamics of Sodium Ions and Water in Swollen Superabsorbent Hydrogels as Studied by ²³Na- and ¹H-NMR
Single and Composite Hot Subdwarf Stars in the Light of 2MASS Photometry
Utilizing the Two Micron All Sky Survey (2MASS) Second Incremental Data
Release Catalog, we have retrieved near-IR magnitudes for several hundred hot
subdwarfs (sdO and sdB stars) drawn from the "Catalogue of Spectroscopically
Identified Hot Subdwarfs" (Kilkenny, Heber, & Drilling 1988, 1992). This sample
size greatly exceeds that of previous studies of hot subdwarfs. Examining 2MASS
photometry alone or in combination with visual photometry (Johnson BV or
Stromgren uvby) available in the literature, we show that it is possible to
identify hot subdwarf stars that exhibit atypically red IR colors that can be
attributed to the presence of an unresolved late type companion. Utilizing this
large sample, we attempt for the first time to define an approximately volume
limited sample of hot subdwarfs. We discuss the considerations, biases, and
difficulties in defining such a sample.
We find that, of the hot subdwarfs in Kilkenny et al., about 40% in a
magnitude limited sample have colors that are consistent with the presence of
an unresolved late type companion. Binary stars are over-represented in a
magnitude limited sample. In an approximately volume limited sample the
fraction of composite-color binaries is about 30%.Comment: to appear in Sept 2003 AJ, 41 pages total, 12 figures, 2 tables are
truncated (full tables to appear in electronic journal or available by
request
Nonionic and ionic surfactants at an interface
A Ginzburg-Landau theory is presented on surfactants in polar binary
mixtures, which aggregate at an interface due to the amphiphilic interaction.
They can be ionic surfactants coexisting with counterions. Including the
solvation and image interactions and accounting for a finite volume fraction of
the surfactant, we obtain their distributions and the electric potential around
an interface in equilibrium. The surface tension is also calculated. The
distribution of the adsorbed ionic surfactant is narrower than that of the
counterions. The adsorption is marked for hydrophilic and hydrophobic pairs of
ionic surfactant and counterions.Comment: 6 figure
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