Contents
Images
Upload your image
DSS Images Other Images
Related articles
The Transit Light Curve Project. X. A Christmas Transit of HD 17156b
Photometry is presented of the 2007 December 25 transit of HD 17156b,which has the longest orbital period and highest orbital eccentricity ofall the known transiting exoplanets. New measurements of the stellarradial velocity are also presented. All the data are combined andintegrated with stellar-evolutionary modeling to derive refined systemparameters. The planet's mass and radius are found to be3.212+0.069 –0.082 M Jup and1.023+0.070 –0.055 R Jup. Thecorresponding stellar properties are 1.263+0.035–0.047 M sun and 1.446+0.099–0.067 R sun. The planet is smaller by1σ than a theoretical solar-composition gas giant with the samemass and equilibrium temperature, a possible indication of heavy-elementenrichment. The midtransit time is measured to within 1 minute and showsno deviation from a linear ephemeris (and therefore no evidence fororbital perturbations from other planets). We provide ephemerides forfuture transits and superior conjunctions. There is an 18% chance thatthe orbital plane is oriented close enough to edge-on for secondaryeclipses to occur at superior conjunction. Observations of secondaryeclipses would reveal the thermal emission spectrum of a planet thatexperiences unusually large tidal heating and insolation variations.
| High-precision effective temperatures of 161 FGK supergiants from line-depth ratios
Precise effective temperatures (Teff) are determined for 161FGK supergiants using method of line-depth ratios. We obtain a set of131 relations for temperatures of supergiants as a function of linedepths. These relations have been calibrated against previouslypublished accurate temperature estimates. The application range of themethod is 3600-7800 K (F0I-K5I). The internal error of a singlecalibration is less than 110 K, while combination of all calibrationsreduces uncertainty to only 5-30 K (standard error). The error in thezero-point is estimated to be less than 100-200 K. A significantadvantage of the line ratio method is its independence of theinterstellar reddening, and only modest sensitivity to abundance,macroturbulence, rotation and other factors.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| An Algol type binary with a δ Scuti component: RZ Cassiopeiae revisited
We present new BV photometry and spectroscopic observations of RZCassiopeiae. The light and radial velocity curves were formed by the newobservations which have been analyzed simultaneously by using theWilson-Dewinney code. The non-synchronous rotational velocityv1sin i = 76 ± 6 km s-1, deduced for theprimary component from the new spectroscopic observations, was alsoincorporated in the analysis. A time-series analysis of the residuallight curves revealed the multi-periodic pulsations of the primarycomponent of RZ Cas. The main peak in the frequency spectrum wasobserved at about 64.197 c d-1 in both B and V bands. Thepulsational constant was calculated to be 0.0116 days. This valuecorresponds to high overtones (n˜6) of non-radial modeoscillations. We find significant changes in the pulsational amplitudeof the primary component from year to year. The peak-to-peak pulsationalamplitude of the main frequency displays a decrease from 0.013 m in 2000to 0.002 m in 2001 and thereafter we have found an increase again in theamplitude to 0.01 m in the year 2002. We propose the mass transfer fromthe cool secondary to the pulsating primary as a possible explanationfor such remarkable changes in the pulsational behavior of the primarycomponent.
| δ Sct-type pulsations in eclipsing binary systems: AB Cas
This paper presents simultaneous Strömgren uvby observationscarried out during the years 1998 and 1999 on the Algol-type eclipsingbinary system AB Cas, where the primary component is a δ Sct-typepulsator. These observations include complete binary uvby light curveswhich have been analysed using the Wilson-Devinney code. The new resultsare compared with those from the literature. The residuals from thecomputed binary light curves were then analysed for their pulsationalcontent. A single frequency was found to be sufficient to describe theout-of-eclipse pulsational behaviour. Nevertheless, some indications ofthe existence of secondary frequencies are also found. The main periodwas found to be constant during the last twenty years, making use of theclassical O-C method, but an increase in its amplitude is detectedduring the year 1998 as compared with other epochs. Concerning thenature of the pulsations, methods based on the phase shifts andamplitude ratios between different filters were used for out-of-eclipsedata and the Spatial Filtration method for observations during theprimary eclipses. All methods lead to the same result: the dominantpulsation is radial, confirming previous results from earlier works. Infact, neither significant amplitude variations nor phase shifts,relative to the pulsational out-of-eclipse behaviour, are found when theprimary component is hidden during primary eclipse. An iterative processwas also carried out to improve both the binary and pulsation solutions,but the final results remained essentially the same.
| The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of 14 000 F and G dwarfs
We present and discuss new determinations of metallicity, rotation, age,kinematics, and Galactic orbits for a complete, magnitude-limited, andkinematically unbiased sample of 16 682 nearby F and G dwarf stars. Our63 000 new, accurate radial-velocity observations for nearly 13 500stars allow identification of most of the binary stars in the sampleand, together with published uvbyβ photometry, Hipparcosparallaxes, Tycho-2 proper motions, and a few earlier radial velocities,complete the kinematic information for 14 139 stars. These high-qualityvelocity data are supplemented by effective temperatures andmetallicities newly derived from recent and/or revised calibrations. Theremaining stars either lack Hipparcos data or have fast rotation. Amajor effort has been devoted to the determination of new isochrone agesfor all stars for which this is possible. Particular attention has beengiven to a realistic treatment of statistical biases and errorestimates, as standard techniques tend to underestimate these effectsand introduce spurious features in the age distributions. Our ages agreewell with those by Edvardsson et al. (\cite{edv93}), despite severalastrophysical and computational improvements since then. We demonstrate,however, how strong observational and theoretical biases cause thedistribution of the observed ages to be very different from that of thetrue age distribution of the sample. Among the many basic relations ofthe Galactic disk that can be reinvestigated from the data presentedhere, we revisit the metallicity distribution of the G dwarfs and theage-metallicity, age-velocity, and metallicity-velocity relations of theSolar neighbourhood. Our first results confirm the lack of metal-poor Gdwarfs relative to closed-box model predictions (the ``G dwarfproblem''), the existence of radial metallicity gradients in the disk,the small change in mean metallicity of the thin disk since itsformation and the substantial scatter in metallicity at all ages, andthe continuing kinematic heating of the thin disk with an efficiencyconsistent with that expected for a combination of spiral arms and giantmolecular clouds. Distinct features in the distribution of the Vcomponent of the space motion are extended in age and metallicity,corresponding to the effects of stochastic spiral waves rather thanclassical moving groups, and may complicate the identification ofthick-disk stars from kinematic criteria. More advanced analyses of thisrich material will require careful simulations of the selection criteriafor the sample and the distribution of observational errors.Based on observations made with the Danish 1.5-m telescope at ESO, LaSilla, Chile, and with the Swiss 1-m telescope at Observatoire deHaute-Provence, France.Complete Tables 1 and 2 are only available in electronic form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/989
| δ Sct-type pulsations in eclipsing binary systems: RZ Cas
We present the results of a three-continent multisite photometriccampaign carried out on the Algol-type eclipsing binary system RZ Cas,in which the primary component has recently been discovered to be aδ Sct-type pulsator. The present observations include, for thefirst time, complete simultaneous Strömgren uvby light curvestogether with a few Crawford Hβ data collected around the orbitalphase of the first quadrature. The new observations confirm thepulsational behaviour of the primary component. A detailed photometricanalysis, based on these observations, is presented for both binarityand pulsation. The results indicate a semidetached system where thesecondary fills its Roche lobe. The appearance of the light curvesreveals the presence of the mass stream from the secondary component anda hotspot where this stream impacts on the surface of the primary star.There are also some indications of chromospheric activity in thesecondary. On the other hand, the pulsational behaviour out-of-primaryeclipse can be well described with only one frequency at 64.1935cd-1 similar to the main peak found by Ohshima et al. Theexistence of multiperiodicity is not confirmed in our data. Concerningthe mode identification, our results indicate non-radial pulsation in ahigh radial order (n= 6), with l= 2, |m|= 1, 2 as the most suitable.However, additional effects must be taken into account in thepredictions. Moreover, the pulsation amplitude in the u band is largerthan in b and v, which is unusual among the δ Sct-type variables.This can be explained as due to pulsation in a high n value and close tothe blue edge of the δ Sct region. On the other hand, the earlydata of Ohshima et al. have also been analysed and similar results arefound concerning the frequency content and pulsational amplitude.Finally, a revision of all the photometric out-of-primary-eclipse datasets available in the literature is made together with some additionalunpublished data leading to interesting findings relative to changestaking place in the pulsation amplitudes and frequencies from season toseason. Furthermore, multiperiodicity is probably present in someepochs.
| New Times of Minima of Eclipsing Binary Systems
Not Available
| The First Eclipsing Binary Observations at the Ulupinar Astrophysics Observatory
Not Available
| Sodium enrichment of stellar atmospheres. I. Non-variable supergiants and bright giants
48 supergiants and bright giants have been observed in order toinvestigate the sodium enrichment of their atmospheres and itsconnection with stellar gravity. We present the equivalent widths of the6154 Å and 6160 Å Na I lines measured from the programspectra, the results of effective temperature determinations, the NLTEsodium abundances, and the derived relation between the sodiumoverabundance and surface gravity.
| Short-Period Light Variation of an Eclipsing Binary System: RZ Cassiopeiae
The eclipsing binary system RZ Cas is known to exhibit variation in itslight curves at the primary minimum, usually showing apartial-eclipse-type curve but sometimes indicating a flat minimum,which is evidence for a total eclipse. We observed RZ Cas not onlyduring the primary eclipse, but also during the out-of-eclipse phase,and we have found a short-period light variation with a frequency of62.20 cycles day-1 (period of 23.15 minutes), whose maximumamplitude is 0.02 mag. This short-period variation can modulate theshape of the light curve at the primary minimum effectively. Thebrightness-color relationship of the short-period variation suggests aδ Scuti type oscillation.
| The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. II. Basic Parameters of Program Stars and the Role of Microturbulence
Paper I of this series presented precise MK spectral types for 372 lateA-, F-, and early G-type stars with the aim of understanding the natureof luminosity classification on the MK spectral classification systemfor this range of spectral types. In this paper, a multidimensionaldownhill simplex technique is introduced to determine the basicparameters of the program stars from fits of synthetic spectra andfluxes with observed spectra and fluxes from Strömgren uvbyphotometry. This exercise yields useful calibrations of the MK spectralclassification system but, most importantly, gives insight into thephysical nature of luminosity classification on the MK spectralclassification system. In particular, we find that in this range ofspectral types, microturbulence appears to be at least as important asgravity in determining the MK luminosity type.
| The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars
This is the first in a series of two papers that address the problem ofthe physical nature of luminosity classification in the late A-, F-, andearly G-type stars. In this paper, we present precise spectralclassifications of 372 stars on the MK system. For those stars in theset with Strömgren uvbyβ photometry, we derive reddenings andpresent a calibration of MK temperature types in terms of the intrinsicStrömgren (b-y)0 index. We also examine the relationshipbetween the luminosity class and the Strömgren c1 index,which measures the Balmer jump. The second paper will address thederivation of the physical parameters of these stars, and therelationships between these physical parameters and the luminosityclass. Stars classified in this paper include one new λ Bootisstar and 10 of the F- and G-type dwarfs with recently discoveredplanets.
| Analyses of the Short-Period Cepheid SU Cassiopeiae
Baade-Wesselink analyses of this important Galactic classical Cepheidprovide new values for the radius, luminosity, distance, and mass andshow SU Cas likely to be pulsating in the first overtone. Application ofa modified Baade-Wesselink technique and the maximum likelihood method,which we have previously applied to δ Scuti-type variables, yieldvalues of R=33.0+/-1.1 Rsolar, L=1536+/-291Lsolar, MV=-3.28-0.19+0.23, r=486+/-52 pc,mass (from the Baade-Wesselink radius), M=6.5+/-0.6 Msolar(assuming first-overtone pulsation), and evolutionary mass,Mev=5.5+/-0.3 Msolar. The results are consistentwith the Hipparcos satellite parallax, 2.31+/-0.58 mas(433+145-87 pc), providing further support forovertone pulsation of SU Cas. In the course of the analyses, amodification to the maximum likelihood method, devised by one of us (W.J. F. W.), is presented as an alternative to the modifications of Laney& Stobie and Coulson, Caldwell, & Gieren. We dedicate this paper toAdriaan J. Wesselink, a dedicated scientist and teacher, and inventor of``the method.''
| A catalog of rotational and radial velocities for evolved stars
Rotational and radial velocities have been measured for about 2000evolved stars of luminosity classes IV, III, II and Ib covering thespectral region F, G and K. The survey was carried out with the CORAVELspectrometer. The precision for the radial velocities is better than0.30 km s-1, whereas for the rotational velocity measurementsthe uncertainties are typically 1.0 km s-1 for subgiants andgiants and 2.0 km s-1 for class II giants and Ib supergiants.These data will add constraints to studies of the rotational behaviourof evolved stars as well as solid informations concerning the presenceof external rotational brakes, tidal interactions in evolved binarysystems and on the link between rotation, chemical abundance and stellaractivity. In this paper we present the rotational velocity v sin i andthe mean radial velocity for the stars of luminosity classes IV, III andII. Based on observations collected at the Haute--Provence Observatory,Saint--Michel, France and at the European Southern Observatory, LaSilla, Chile. Table \ref{tab5} also available in electronic form at CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Detection of the delta Scuti Oscillation in RZ Cassiopeiae
PMT and CCD photometry of the RZ Cas were carried out. The 22-minperiodic oscillations with amplitude of about 20-mmag amplitude weredetected not only in primary minimum but also in secondary minimum andin out-of-eclipse. The oscillations should be the Delta Scutivariability.
| UBV beta Database for Case-Hamburg Northern and Southern Luminous Stars
A database of photoelectric UBV beta photometry for stars listed in theCase-Hamburg northern and southern Milky Way luminous stars surveys hasbeen compiled from the original research literature. Consisting of over16,000 observations of some 7300 stars from over 500 sources, thisdatabase constitutes the most complete compilation of such photometryavailable for intrinsically luminous stars around the Galactic plane.Over 5000 stars listed in the Case-Hamburg surveys still lackfundamental photometric data.
| Photoelectric and CCD times of minima of 19 eclipsing binary systems
We present several photoelectric and unfiltered CCD minima observationsof 19 eclipsing binaries. Most of them are apsidal motion stars (or atleast candidate ones).
| BVRI Observations of an eclipse of RZ Cas
BVRI photometry of an eclipse of the RZ Cas is reported.
| The Hα behavior in bright giant stars.
We report high resolution spectroscopic observations of the Hαline profile for a sample of 32 bright giant stars with spectral typebetween F3II and G5II. By studying the link between the Hαbehavior and the stellar rotation in such class of luminosity we havefound no clear evidence that the rotational discontinuity establishedaround F9II is related with the Hα profiles. No emission features,neither time variations or asymmetries on the Hα line profileshave been detected for the bright giants analysed in the present work.
| Photoelectric minima of 30 eclipsing binary systems
Not Available
| B and V photometry and analysis of the eclipsing binary RZ CAS
Photoelectric light curves of the eclipsing binary RZ Cas are presentedfor B and V filters. The light curves are analyzed for light andgeometrical elements, starting with a previously suggested preliminarymethod. The approximate results thus obtained are then optimised throughthe Wilson-Devinney computer programs.
| A Total Eclipse in RZ Cassiopeiae?
Not Available
| Hyades and Sirius supercluster members brighter than magnitude(V) 7.1. I - The first six hours of right ascension
This is the first of four papers listing the probable members of theHyades and Sirius superclusters among stars brighter than V = 7.1 mag.The star sample is contained in the Bright Star Catalogue and itsSupplement, augmented with a further supplement of 550 stars foundduring various observing programs over the past 40 years. Accurate,four-color and H-beta, or (RI), photometry is available for most of thesupercluster members. The criteria for membership are the comparisons ofthe proper motion, radial velocity, and luminosity obtained from thesupercluster parameters with the observed motions and the luminosityderived from the photometric parameters. New proper motions, based onall available catalogs, have been derived for the additional 550 starsdiscussed here, as well as for all supercluster members.
| Ultraviolet and optical studies of binaries with luminous cool primaries and hot companions. II - BVRI observations
Johnson system BVRI measurements are presented for 117 stars, most ofthem with no previous R and I photometry and many with no previous B andV. The prime objects for measurement are unresolved or nearly unresolvedbinaries containing a late-type giant or supergiant and an early-typecompanion. Other objects on the program include suspected binaries andother F-G giants and supergiants lacking at least R and I magnitudes.The variable F and G supergiants 1 Mon, 89 Her, HR 7308, HR 8157, HR8752, and rho-Cas and the eclipsing systems W Ser and ST Aqr wereobserved; HR 8752 showed significant dimming and cooling over 125 days.Several of Halliwell's (1979) candidates for nearby stars were measured.
| Photoelectric observations of RZ Cassiopeiae.
Abstract image available at:http://adsabs.harvard.edu/abs/1975PASP...87..909K
| The Light-curves of Eclipsing Binaries
Not Available
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Cassiopeia |
| Right ascension: | 02h35m43.85s |
| Declination: | +68°22'03.9" |
| Apparent magnitude: | 6.638 |
| Distance: | 154.083 parsecs |
| Proper motion RA: | 44 |
| Proper motion Dec: | -19.9 |
| B-T magnitude: | 7.126 |
| V-T magnitude: | 6.679 |
Catalogs and designations:
|
INHABITED SKY
