scholarly journals The Absolute Dimensions and Masses of IQ Persei

1985 ◽  
Vol 111 ◽  
pp. 389-389
Author(s):  
Claud H. Lacy
Keyword(s):  
Cross Correlation ◽  
Main Sequence ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Apsidal Motion ◽  
Orbital Elements ◽  
Photometric Observations ◽  
The Absolute ◽  
Motion Period ◽  
Absolute Dimensions

High signal-to-noise ratio spectrometric observations of the large light-ratio eclipsing binary IQ Per (B7 + A2) have been obtained with the coudé Reticon spectrograph of the 2.7 m reflector at McDonald Observatory. Absorption lines of the secondary are seen at the 4481 Å MgII line and the 4549 Å TiII + FeII blend. Radial velocities of both components have been measured by cross-correlation techniques and spectroscopic orbits have been computed. The fitted orbits have an eccentricity (0.075 ± 0.007) that is consistent with the photometric orbit of Hall, Gertken and Burke (1970). Young's (1975) “provisional” estimate of K2 is about 14% too small. Absolute dimensions and masses have been computed from Hall et al.'s (1970) photometric orbit and the new spectroscopic orbit. Additionally, V-R photometric observations obtained by M. Frueh at McDonald Obs. have been analysed by Popper with light curve synthesis techniques (WINK and EBOP). The relative radii of the new photometric orbits differ by less than 2% from the previous orbits, and the other orbital elements also show excellent agreement. The absolute dimensions and masses are (3.51 ± 0.04m⊙, 2.46 ± 0.04 R⊙) for the primary and (1.73 ± 0.02m⊙, 1.50 ± 0.03 R⊙) for the secondary. Both stars are near the zero-age main sequence. The value of ω has changed significantly between the epoch of Hall, Gertken, and Burke's (1970) observations and my own due to apsidal motion. The apsidal motion period is estimated to be in the interval 90 ≤ τ ≤ 180 yr.

scholarly journals Photometric and Spectroscopic Study of R CMa

1984 ◽  
Vol 80 ◽  
pp. 229-236
Author(s):  
K. R. Radhakrishnan ◽  
M. B. K. Sarma ◽  
K. D. Abhyankar
Keyword(s):  
Spectroscopic Study ◽  
Spectral Type ◽  
Main Sequence ◽  
Large Fraction ◽  
Roche Lobe ◽  
Orbital Elements ◽  
System A ◽  
Original Mass ◽  
The Absolute ◽  
Absolute Dimensions

AbstractUVB Flight curves and spectrograms of R CMa obtained with the 48-inch telescope of Japal-Rangapur Observatory during 1980-82 have been used for deriving the eclipse and orbital elements as well as the absolute dimensions of the components. The primary is found to be a Main-Sequence F2V star of mass 1.52 M⊙ and the secondary a subgiant star of spectral type G8 and mass 0.20 M⊙ which fills its Roche lobe, in agreement with Kopal and Shapley (1956) results, Kopal (1959), or Sahade's (1963) results. From a consideration of the possible evolution of this system it is concluded that a large fraction of the original mass of the secondary is lost from the system. A study of the period changes indicates the possible presence of a third component of mass of about 0.5 M⊙ which is most likely to be an M dwarf.

scholarly journals Photometric Study of two Southern Algol Type Binaries

1989 ◽  
Vol 107 ◽  
pp. 376-376
Author(s):  
K. D. Abhyankar ◽  
M. L. Vyas
Keyword(s):  
Spectroscopic Data ◽  
Main Sequence ◽  
Light Curves ◽  
The Other ◽  
Main Sequence Star ◽  
Photometric Study ◽  
The Absolute ◽  
Better Than ◽  
Absolute Dimensions

Complete UBV light-curves of RR-Lep and RX-Hya have been obtained during 1983-87 seasons. Preliminary elements were computed using modified Wellmann’s method. With these parameters as inputs Wilson-Devinney program was executed for Blue and Yellow passbands simultaneously in detached and semi-detached modes for both the systems. The semidetached mode fitted better than the other solution for both the systems. For RR-Lep, the absolute dimensions were computed by assuming the primary to be a slightly evolved main sequence star. For RX-Hya, the absolute dimensions were computed using Struve’s spectroscopic data. The following table gives all the elements for both the systems. The secondaries of both the systems are overluminous for their masses suggesting that they have lost considerable mass.

scholarly journals HD 42659: the only known roAp star in a spectroscopic binary observed with B photometry, TESS, and SALT

2019 ◽  
Vol 489 (3) ◽  
pp. 4063-4071 ◽  
Author(s):  
Daniel L Holdsworth ◽  
Hideyuki Saio ◽  
Donald W Kurtz
Keyword(s):  
Signal To Noise Ratio ◽  
Rotation Frequency ◽  
Close Binaries ◽  
High Signal ◽  
Pulsation Frequency ◽  
Orbital Parameters ◽  
Mode Amplitude ◽  
Photometric Observations ◽  
Short Period ◽  
Roap Star

ABSTRACT We present a multi-instrument analysis of the rapidly oscillating Ap (roAp) star HD 42659. We have obtained B photometric data for this star and use these data, in conjunction with the Transiting Exoplanet Survey Satellite (TESS) observations, to analyse the high-frequency pulsation in detail. We find a triplet that is split by the rotation frequency of the star (νrot = 0.3756 d−1; Prot = 2.66 d) and present both distorted dipole and distorted quadrupole mode models. We show that the pulsation frequency, 150.9898 d−1 (Ppuls = 9.54 min), is greater than the acoustic cut-off frequency. We utilize 27 high-resolution ($R\simeq 65\, 000$), high signal-to-noise ratio (∼120) spectra to provide new orbital parameters for this, the only known roAp star to be in a short-period binary (Porb = 93.266 d). We find the system to be more eccentric than previously thought, with e = 0.317, and suggest the companion is a mid-F to early-K star. We find no significant trend in the average pulsation mode amplitude with time, as measured by TESS, implying that the companion does not have an effect on the pulsation in this roAp star. We suggest further photometric observations of this star, and further studies to find more roAp stars in close binaries to characterize how binarity may affect the detection of roAp pulsations.

scholarly journals Li abundances and chromospheric activity of BY Dra type stars

2009 ◽  
Vol 5 (S268) ◽  
pp. 343-344
Author(s):  
Tamara V. Mishenina ◽  
Caroline Soubiran ◽  
Valery V. Kovtyukh ◽  
Stanislav I. Belik
Keyword(s):  
Cross Correlation ◽  
Signal To Noise Ratio ◽  
Large Fraction ◽  
Ratio Method ◽  
Clear Correlation ◽  
High Signal ◽  
Echelle Spectrograph ◽  
Active Stars ◽  
Ionization Balance ◽  
Line Depth

AbstractAtmospheric parameters and Li abundances have been determined for 162 stars observed at high resolution, high signal to noise ratio with the ELODIE echelle spectrograph (OHP, France). Among them, about 70 stars are active stars with a large fraction of BY Dra type stars. For all stars, rotational velocities were obtained with a calibration of the cross-correlation function, effective temperatures by the line depth ratio method, surface gravities by the parallaxe method and by the ionization balance of iron. The frequency of stars with observed lithium is significantly higher in active stars than in non active stars. Among active stars, no clear correlation has been found between different indicators of activity for our sample stars, but some correlation of an index R′H K and vsini is observed.

scholarly journals High Signal-To-Noise Ratio - the Spectroscopic Key to Algol Systems

1989 ◽  
Vol 107 ◽  
pp. 245-255
Author(s):  
Jocelyn Tomkin
Keyword(s):  
Main Sequence ◽  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Large Fraction ◽  
High Signal ◽  
Signal To Noise ◽  
Algol System ◽  
Low Mass ◽  
Noise Ratio ◽  
Cno Abundances

AbstractThe usefulness of high signal-to-noise-ratio spectra for both radial-velocity and abundance studies of Algol systems is emphasised. It is shown that division by a hot star is a worthwhile step in pursuit of this objective. A preliminary analysis of high signal-to-noise-ratio, red and near-infrared, Reticon observations of R CMa shows that its primary has solar CNO abundances within the 0.3 dex observational error. The low-mass (0.17 m⊙) secondary of this Algol system must have lost a large fraction of its original mass. Some of this material would have been extensively processed during the secondary’s main-sequence lifetime and would therefore have had a highly non-solar CNO-abundance distribution. The lack of serious contamination of the primary’s abundances is consistent with most, but not all, plausible mass-transfer scenarios.

scholarly journals Seismology of southern Be stars

1994 ◽  
Vol 162 ◽  
pp. 104-105
Author(s):  
Eduardo Janot-Pacheco ◽  
Nelson Vani Leister
Keyword(s):  
High Resolution ◽  
Signal To Noise Ratio ◽  
Ccd Camera ◽  
High Signal ◽  
Be Stars ◽  
Signal To Noise ◽  
Photometric Variability ◽  
Spectroscopic Observations ◽  
Photometric Observations ◽  
Noise Ratio

We have started in 1990 a search for moving bumps in the HeI λ 667.8 nm of mainly southern, bright Be stars. The objects of our sample have been selected on the basis of photometric variability (Cuypers et al., 1989). High resolution (R≥ 30,000), high signal-to-noise ratio (S/R≥ 300) spectroscopic observations have been performed at the brazilian Laboratório Nacional de Astrofísica with a CCD camera attached to the coudé spectrograph of the 1.60 m telescope (e.g. Table I). Several hundred spectra have been taken during the last three years. Photometric observations simultaneous with spectroscopy were made on the same site in July 1992 with a two-channel photometer (Stromgren b filter) and a CCD camera (Johnson B filter) installed at two 0.60 m telescopes. The idea is try to disentangle the controversy between NRP and RM models with the help of simultaneous spectroscopy and photometry.

scholarly journals Comparison of Terrestrial and Lunar Time Scales by Giant Pulsar Impulses

2021 ◽  
Vol 65 (11) ◽  
pp. 1136-1144
Author(s):  
A. E. Rodin ◽  
V. V. Oreshko ◽  
V. A. Fedorova
Keyword(s):  
Time Scales ◽  
Cross Correlation ◽  
Arrival Time ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
The Moon ◽  
Recording Equipment ◽  
Giant Pulses ◽  
Cross Correlation Analysis ◽  
Pulse Arrival

Abstract We have developed a model for the time delay of pulse arrival between stations on the Moon and Earth. Comparison of the lunar and terrestrial time scales is proposed to be carried out by comparing the arrival time moments of giant pulses from pulsars. A method for such a comparison has been developed based on the cross-correlation analysis of the received pulses. Using the example of giant pulses from the pulsar PSR 0531+21, we showed that the error of comparing scales in the case of a high signal-to-noise ratio reaches a sub-discrete level and, thus, is determined by the reception band of the recording equipment.

scholarly journals The Intriguing PMS Eclipsing (Triple) System TY CrA

2001 ◽  
Vol 200 ◽  
pp. 449-453
Author(s):  
Luiz Paulo R. Vaz
Keyword(s):  
Triple System ◽  
Main Sequence ◽  
Evolutionary Models ◽  
The Absolute ◽  
Absolute Dimensions

The absolute dimensions of the eclipsing pair in the triple system TY CrA provide constraints on the evolutionary models for both main sequence and pre-main sequence phases.

scholarly journals Multiple stellar systems

1986 ◽  
Vol 118 ◽  
pp. 441-442
Author(s):  
A. Duquennoy ◽  
M. Mayor
Keyword(s):  
Radial Velocity ◽  
Small Amplitude ◽  
Cross Correlation ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Correlation Technique ◽  
Multiple Systems ◽  
Triple Systems ◽  
The Cross

A spectroscopic survey of visual binaries with known orbital elements has been carried out with the radial velocity scanner CORAVEL at the Haute-Provence Observatory, since 1977, (Baranne, Mayor, Poncet, 1979). This survey of more than 100 visual systems, selected from Dommanget's catalogue (1967) (see also a new edition 1982) was first devoted to the determination of stellar masses. Several multiple systems were detected and have permitted also a study of the structure of triple systems. We have detected and measured in particular a class of triple systems with radial velocity variations of small amplitude. Taking advantage of the high resolution and high signal-to-noise ratio accessible with the cross-correlation technique, such small amplitude radial velocity curves are sometimes derived only through the change of width and shape of the cross-correlation function. Let us recall that the cc-function of a SB2 (or SB3) system is only the weighted sum of the individual cc-functions (Mayor, 1985). This property of the cross-correlation combined with the linearity of the detector allow a very simple analysis of blended dips. The full width at half depth of the cross-correlation dip is about FWHD = 16 km/s (in absence of noticeable rotation). Analysis of blended systems allows a good determination of the two individual velocities if the difference |vr1 -Vr2| is equal or larger than about 0.15 *FWHD (about 2 km/s).

scholarly journals Doppler imaging of the active star PW And

2009 ◽  
Vol 5 (S264) ◽  
pp. 90-92
Author(s):  
Sheng-hong Gu ◽  
Andrew Collier Cameron ◽  
Kang Min Kim
Keyword(s):  
High Latitude ◽  
Spectroscopic Data ◽  
Main Sequence ◽  
Signal To Noise Ratio ◽  
Doppler Imaging ◽  
High Signal ◽  
Imaging Method ◽  
Deconvolution Method ◽  
Low Latitude ◽  
Spot Activity

AbstractWe present spot activity of the K2V pre-main-sequence star PW And based on the high-resolution spectroscopic data obtained at Xinglong station and BOAO in 2005 November and December. Using the Least-Squares Deconvolution method, we have derived time series of composite profiles of PW And with high signal to noise ratio. These have been used to reconstruct its starspot pattern via the Doppler imaging method. The result shows that intermediate to high-latitude spots are the dominant features and weak low-latitude spots also appear. Comparing Doppler images from two data subsets, it can be found that almost no difference between two images exists except the small position evolution of weak low-latitude spots, which suggests that the intermediate to high-latitude spots have longer lifetimes than one month, and the low-latitude spots have shorter lifetimes.

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