We propose a new approach to measure differential radial velocities, mainly for single-lined spectroscopic binaries. The proposed procedure – TIRAVEL (Template Independent RAdial VELocities) – does not rely on a prior theoretical or observed template, but instead looks for a set of relative Doppler shifts that simultaneously optimizes the alignment of all the observed spectra. We suggest a simp...

We present paper six of the NIRSPEC Brown Dwarf Spectroscopic Survey, an analysis of multi-epoch, highresolution (R ∼ 20,000) spectra of 25 field dwarf systems (3 late-type M dwarfs, 16 L dwarfs, and 6 T dwarfs) taken with the NIRSPEC infrared spectrograph at the W. M. Keck Observatory. With a radial velocity (RV) precision of ∼2 km s, we are sensitive to brown dwarf companions in orbits with p...

We present 594 radial velocity measurements for 71 white dwarfs obtained during our search for binary white dwarfs and not reported elsewhere. We identify three excellent candidate binaries, which require further observations to confirm our preliminary estimates for their orbital periods, and one other good candidate. We investigate whether our data support the existence of a population of sing...

We report on the development of a technique for precise radial-velocity measurements of cool stars and brown dwarfs in the near infrared. Our technique is analogous to the Iodine (I2) absorption cell method that has proven so successful in the optical regime. We rely on telluric CH4 absorption features to serve as a wavelength reference, relative to which we measure Doppler shifts of the CO and...

Context. Radial-velocity (RV) signals arising from stellar photospheric phenomena are the main limitation for precise RV measurements Those signals induce RV variations an order of magnitude larger than the signal created by the orbit of Earth-twins, thus preventing their detection. Aims. Different methods have been developed to mitigate the impact of stellar RV signals. The goal of this paper ...

We present new Hα Fabry-Perot observations of the HH 1/2 system. Line profiles, barycenter radial velocity maps and dispersion maps are derived from the channel maps of HH 1 and HH 2. The radial velocity barycenter maps of both HH 1/2 show a general trend of “red-shifted upstream/blue-shifted downstream” pattern. A “direct+scattered” component model for three emitting condensations is qualitati...

We obtained time series of spectra with high S/N and high resolution in wavelength and time of early-type A and late-type B supergiants (cf. Kaufer et al. 1996a, Paper i, and Kaufer et al. 1996b, Paper ii for the analysis of the variability of the stellar envelopes). In this work we inspect the time variations of the numerous photospheric line profiles in the optical spectrum. We find complex c...

The problem of door opening is fundamental for robots operating in domestic environments. Since these environments are generally less structured than industrial environments, several types of uncertainties associated with the dynamics and kinematics of a door must be dealt with to achieve successful opening. This paper proposes a method that can open doors without prior knowledge of the door ki...

Aims. It is known that stellar activity may complicate the analysis of high-precision radial-velocity spectroscopic data when looking for exoplanets signatures. We aim at quantifying the impact of stellar spots on stars with various spectral types and rotational velocities and comparing the simulations with data obtained with the HARPS spectrograph. Methods. We have developed detailed simulatio...

in this paper, changes of casson non-newtonian fluid velocity profile, for different distribution of porosity, have been investigated. for distribution of porosity, fixed, radial and exponential variations has been considered. for all three states, brinkman model has been used as momentum equation. since the casson fluid is a good model for blood, this analysis can be used in studying about cho...