In the course of other work I have obtained complete identifications for a problematic list of late-type stars by Dolidze (1975AbaOB..47....3D). The charts were used to make the identifications. Since numerous substantial errors were found that have propagated elsewhere in the literature, it was thought useful to publish the list separately. The corrections allow linkage of the stars to other catalogues in the visible and infrared. This complements a second similar list of late-M stars by Dolidze (Dolidze, 1975AbaOB..47..171D, Skiff, 1997IBVS.4417....1S).
In the course of the near-complete Michigan Spectral Survey of the Southern sky, 624 dwarf stars of type K2V and later have been identified. Many of these stars are previously unrecognized as nearby late dwarfs. The plates used are the Curtis Schmidt 10{deg} prism plates taken for the HD reclassification project.
Stellar population studies in the infrared (IR) wavelength range have two main advantages with respect to the optical regime: they probe different populations, because most of the light in the IR comes from redder and generally older stars and allow us to see through dust because the IR light is less affected by extinction. Our project investigates the sensitivity of various spectral features in the 1-5um wavelength range to the physical properties of stars (Teff, [Fe/H], logg) and aims to objectively define spectral indices that can characterize age and metallicity of unresolved stellar populations. We implemented a method that uses derivatives of the indices as functions of Teff, [Fe/H] of log g across the entire available wavelength range to reveal the most sensitive indices to these parameters and the ranges in which these indices work. Here, we complement the previous work in the I and K bands reporting a new system for Y, J, H and L atmospheric windows. We list the equivalent widths of these indices for the Infrared Telescope Facility (IRTF) spectral library stars.
I have reinterpreted Rucinski's line profiles (broadening functions) for the hot A-type W Ursae Majoris binary AW UMa in terms of various contact models, finding that the detached/semidetached geometry he postulates does not fit the system's light variation or its line profiles. The highly overcontact geometry that actually fits the system's ellipsoidal light variation reproduce the total breadth of the lines but give profiles too broad to fit their shapes. The best solution to this dilemma is differential rotation of both stars in which the mid-latitudes are rotating 20-30 per cent slower than synchronously. This approach preserves the traditional light-curve solution and explains the drift of ripples seen in the line profiles. In addition, there are obviously other flows superimposed on the rotation which make the profiles asymmetrical. Fitting the line profiles is complicated by uncertainties in how the equivalent widths of the lines change with effective temperature and how much they are limb darkened. The contribution of any point on the stellar surface to the equivalent width depends only very weakly on local temperature throughout the range of W UMa binaries. The limb darkening of the lines is probably small, although the effect remains unexplored. I also speculate about the nature of hypothetical star-spots in this system.
A high-resolution spectroscopic survey in the 6380-6460{AA} region of 224 slowly-rotating M-K class III giants is presented. Spectral line-depth ratio are calibrated against effective temperature obtained from B-V and V-I color indices in the range 3200-7500K (M6-A9). A table of polynomial coefficients for 12 line-ratio-Teff relations can be used to derive Teff of F-M stars to within 33K (rms), and of early-F and mid-to-late M stars to within 77-106K (rms).
Flares on dM stars contain plasmas at very different temperatures and thus affect a wide wavelength range in the electromagnetic spectrum. While the coronal properties of flares are studied best in X-rays, the chromosphere of the star is observed best in the optical and ultraviolet ranges. Therefore, multiwavelength observations are essential to study flare properties throughout the atmosphere of a star.
A large number of stars from photometrically homogeneous catalogs are used to derive the normal energy distribution for giants of 15 spectral subclasses. To judge the reliability of the results obtained, the mean (B-V)_S_ color indices calculated for a sample of stars with spectrophotometry are compared with the mean (B-V) for a complete sample of stars of a given subclass from the Bright Star (<V/50>) catalog.
The table provides the heliocentric radial velocities (between parenthesis) for 81 Mira and semi-regular variables monitored at the Observatoire de Haute Provence with the ELODIE spectrograph. The different types of cross-correlation functions (CCFs) obtained with the K0 III- and M4 V-templates are coded as defined in the paper (see also Note 1 below).
We have developed an analytical equation of state (EOS) for magnetized fully-ionized plasmas that cover a wide range of temperatures and densities, from low-density classical plasmas to relativistic, quantum plasma conditions. This EOS directly applies to calculations of structure and evolution of strongly magnetized white dwarfs and neutron stars. We review available analytical and numerical results for thermodynamic functions of the nonmagnetized and magnetized Coulomb gases, liquids, and solids. We propose a new analytical expression for the free energy of solid Coulomb mixtures. Based on recent numerical results, we have constructed analytical approximations for the thermodynamic functions of harmonic Coulomb crystals in quantizing magnetic fields. The analytical description ensures a consistent evaluation of all astrophysically important thermodynamic functions based on the first, second, and mixed derivatives of the free energy. Our numerical code for calculation of thermodynamic functions based on these approximations has been made publicly available. Using this code, we calculate and discuss the effects of electron screening and magnetic quantization on the position of the melting point in a range of densities and magnetic fields relevant to white dwarfs and outer envelopes of neutron stars. We consider also the thermal and mechanical structure of a magnetar envelope and argue that it can have a frozen surface which covers the liquid ocean above the solid crust.
