The spectra of HT Virginis were collected at 0.5m Newtonian telescope (PST1) equipped with echelle spectrograph (R=40 000). The focal length of the telescope is 2.25m. The data set was obtained between 6 May 2011 and 21 May 2011. The signal-to-noise ratio is from 10 to 85. The collected data covered spectral range from 4288 to 7517{AA}. The continuum of the spectra was normalised to 1 while the wave length scale was not corrected to the heliocentric values. The spectra contain light from the eclipsing pair B and component A which is SBI type (A/B separation is 0.56 arcsec).
NGC 7009 is a fascinating example of a high-excitation, elliptical planetary nebula (PN) containing circumnebular rings, and FLIERs and jets along the major axis. We present visual spectroscopy along multiple position angles through the nucleus, taken with the Observatorio Astronomico Nacional (Mexico); mid-infrared (MIR) spectroscopy and imaging acquired using the Infrared Space Observatory (ISO) and Spitzer Space Telescope (SST), and narrow-band imaging obtained using the Hubble Space Telescope (HST).
We have made new observations of the spectrum of singly ionized chromium (CrII) in the region 2850-37900{AA} with the National Institute of Standards and Technology 2m Fourier transform spectrometer. These data extend our previously reported observations in the near-ultra-violet region. We present a comprehensive list of more than 5300 CrII lines classified as transitions among 456 even and 457 odd levels, 179 of which are newly located in this work. Using highly excited levels of the 3d^4^(^5^D)5g, 3d^4^(^5^D)6g, and 3d^4^(^5^D)6h configurations, we derive an improved ionization energy of 132971.02+/-0.12cm^-1^ (16.486305+/-0.000015eV).
Based on echelle spectra obtained at the prime focus of the 6-m telescope, the detailed chemical composition of one of the components of the bipolar nebula identified with the intense infrared source AFGL 2688 was determined by the model-atmosphere method.
Measurements of ultraviolet line fluxes from Space Telescope Imaging Spectrograph and Far-Ultraviolet Spectroscopic Explorer spectra of the K2-dwarf eps Eri are reported. These are used to develop new emission measure distributions and semi-empirical atmospheric models for the chromosphere and lower transition region of the star. These models are the most detailed constructed to date for a main-sequence star other than the Sun. New ionization balance calculations, which account for the effect of finite density on dielectronic recombination rates, are presented for carbon, nitrogen, oxygen and silicon. The results of these calculations are significantly different from the standard Arnaud & Rothenflug ion balance, particularly for alkali-like ions. The new atmospheric models are used to place constraints on possible first ionization potential (FIP)-related abundance variations in the lower atmosphere and to discuss limitations of single-component models for the interpretation of certain optically thick line fluxes.
Since methyl formate (O=CH-O-CH_3_) is found to have a high abundance in Hot molecular cores and other types of clouds in the galactic center, it is reasonable to search among such sources for detectable abundances of the more complex analog ethyl formate (O=CH-OOC_2_H_5_). Following a previous study of the millimeter-wave spectrum of ethyl formate, we have extended the analysis of the vibrational ground state of the trans and gauche conformers of ethyl formate into the submillimeter-wave range. Over 2200 new spectral lines have been measured and analyzed at frequencies up to 380GHz. Fitting the data for each conformer to a Watson A-reduced asymmetric-top Hamiltonian has allowed us to predict the frequencies and intensities of many more transitions through 380GHz.
Based on CCD-spectra obtain with the 6-m telescope, detailed chemical composition of the IR source IRAS 23304+6147 identified with the faint star is studied.
We report the identification of LSR J0745+2627 in the United Kingdom InfraRed Telescope Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) as a cool white dwarf with kinematics and age compatible with the thick-disk/halo population. LSR J0745+2627 has a high proper motion (890mas/yr) and a high reduced proper motion value in the J band (H_J=21.87). We show how the infrared-reduced proper motion diagram is useful for selecting a sample of cool white dwarfs with low contamination. LSR J0745+2627 is also detected in the Sloan Digital Sky Survey (SDSS) and the Wide-field Infrared Survey Explorer (WISE). We have spectroscopically confirmed this object as a cool white dwarf using X-Shooter on the Very Large Telescope. An analysis of its spectral energy distribution reveals that its atmosphere is compatible with a pure-H composition model with an effective temperature of 3880+/-90K. This object is the brightest pure-H ultracool white dwarf (Teff<4000K) ever identified. We have constrained the distance (24-45pc), space velocities and age considering different surface gravities. The results obtained suggest that LSR J0745+2627 belongs to the thick-disk/halo population and is also one of the closest ultracool white dwarfs.