Оглавление
Изображения
Загрузить ваше изображение
DSS Images Other Images
Публикации по объекту
Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Spectroscopy of the Lens Galaxy of Q0957+561A,B: Implications of a Possible Central Massive Dark Object
We present new long-slit William Herschel Telescope spectroscopicobservations of the lens galaxy G1 associated with the double-imaged QSO0957+561A,B. The central stellar velocity dispersion obtained,σl=310+/-20 km s-1, is in reasonableagreement with other measurements of this dynamical parameter. Using allupdated measurements of the stellar velocity dispersion in the internalregion of the galaxy (at angular separations <1.5") and a simpleisotropic model, we discuss the mass of a possible central massive darkobject. We find that the data of Falco et al. suggest the existence ofan extremely massive object of (0.5-2.1)x1010 h-1Msolar (80% confidence level), whereas the inclusion of veryrecent data substantially changes the results: the compact central massmust be <=6x109 h-1 Msolar at the90% confidence level. We note that, taking into account all theavailable dynamical data, a compact nucleus with a mass of109 h-1 Msolar (best fit) cannot beruled out.
| Velocity Dispersion of the Gravitational Lens 0957+561
The lens system 0957+561 is the first gravitational lens system to bediscovered and the first for which a time delay was measured. Becausethe system is unusually rich in observables such as image positions,fluxes, VLBI structure, and polarization it has been modeled quiteextensively. However, since it resides in a cluster providingsubstantial convergence, the velocity dispersion of the lensing galaxyis an important component to models. We have measured this dispersion tobe 288+/-9 km s^-1 (1 sigma), which implies a Hubble constant of 72+/-7km s^-1 Mpc^-1 (1 sigma) according to the preferred fine guidancesensors model of Grogin and Narayan and 70+/-7 km s^-1 Mpc^-1 (1 sigma)using the softened power-law sphere model. The unknown velocitydispersion anisotropy of the central galaxy produces an additionaluncertainty of perhaps 15% or more. We see no variation in dispersionwith position to a radius of +/-3". In addition to a galaxy from thebackground cluster at z=0.5, our slit serendipitously picked up a galaxyat z=0.448 and two galaxies that may be part of a background cluster ata redshift of z=0.91.
| An Estimate of H 0 from Keck Spectroscopy of the Gravitational Lens System 0957+561
We present long-slit LRIS/Keck spectroscopic observations of thegravitational lens system 0957+561. Averaged over all of our data, therest-frame velocity dispersion sigma v of the central lens galaxy G1 issigma v = 279 +/- 12 km s-1. However, there appears to be a significantdecrease in sigma v as a function of distance from the center of G1 thatis not typical of the brightest cluster galaxies. Within 0."2 of thecenter of G1, we find the average sigma v = 316 +/- 14 km s-1, whereasfor positions greater than 0."2 from the center of G1, we find theaverage sigma v = 266 +/- 12 km s-1. A plausible explanation is that G1contains a central massive dark object of mass MMDO ~ 4 x 109h^{-1}100 Mȯ (h100 = H0/100 km s-1 Mpc-1), whichcontributes to the central velocity dispersion, and that the outer valueof sigma v is the appropriate measure of the depth of the potential wellof G1. The determination of a luminosity-weighted estimate of sigma v isessential for a determination of H0 from Q0957+561; our accuratemeasurements remove one of the chief uncertainties in the assumed formof the mass distribution of the lens. Thus, with the recent apparentreduction in the uncertainty in the measurement of the time delay forthe images A and B of Q0957+561, Delta tau BA = 417 +/- 3 days (Kundicet al.), we obtain an estimate for the Hubble constant: H0 = 62 +/- 7 kms-1 Mpc-1. If for some reason the trend of sigma v with slit position isspurious and we should use the dispersion averaged along the slit, thenthe estimate of H0 increases to 67 +/- 8 km s-1 Mpc-1. These standarderrors, however, do not include any contribution from any errors in theassumed form of the mass distribution of the lens. In particular, weused the mass model described by Falco, Gorenstein, & Shapiro, asupdated by Grogin & Narayan. The reduced chi 2 of model fits to theavailable position and magnification data for this system is relativelyhigh (~4), indicating that the estimate of H0 may have a significantcontribution from model errors. Further observations, discussed herein,should allow such errors to be estimated reliably.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| UBVRI photometry of FKSZ stars. IV
The paper presents UBVRI photometry, in the Kron-Cousins system, for 117stars of the Catalog of Fundamental Faint Stars in the declination zone+18-0 deg. The observations were performed from July 1988 to March 1990with the ESO 0.50-m telescope at the ESO in La Silla, Chile. The resultsof 24 nights of observations are reported.
| Catalog of Indidual Radial Velocities, 0h-12h, Measured by Astronomers of the Mount Wilson Observatory
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJS...19..387A&db_key=AST
| Vitesses radiales dans 4 champs de petite latitude galactique.
Not Available
|
Добавить новую статью
Внешние ссылки
- - Внешних ссылок не найдено -
Добавить внешнюю ссылку
Группы:
|
Наблюдательные данные и астрометрия
| Созвездие: | Близнецы |
| Прямое восхождение: | 07h20m37.88s |
| Склонение: | +14°53'58.0" |
| Видимая звёздная величина: | 8.508 |
| Расстояние: | 684.932 парсек |
| Собственное движение RA: | -0.4 |
| Собственное движение Dec: | -7.2 |
| B-T magnitude: | 10.029 |
| V-T magnitude: | 8.634 |
Каталоги и обозначения:
|
