Оглавление
Изображения
Загрузить ваше изображение
DSS Images Other Images
Публикации по объекту
A catalog of bright calibrator stars for 200-m baseline near-infrared stellar interferometry
We present in this paper a catalog of reference stars suitable forcalibrating infrared interferometric observations. In the K band,visibilities can be calibrated with a precision of 1% on baselines up to200 meters for the whole sky, and up to 300 meters for some part of thesky. This work, extending to longer baselines a previous catalogcompiled by Bordé et al. (2002, A&A, 393, 183), isparticularl y well adapted to hectometric-class interferometers such asthe Very Large Telescope Interferometer (VLTI, Glindemann et al. 2003,Proc. SPIE, 4838, 89) or the CHARA array (ten Brummelaar et al. 2003,Proc. SPIE, 4838, 69) when one is observing well-resolved, high-surfacebrightness objects (K 8). We use the absolute spectro-photometriccalibration method introduced by Cohen et al. (1999, AJ, 117, 1864) toderive the angular diameters of our new set of 948 G8-M0 calibratorstars extracted from the IRAS, 2MASS and MSX catalogs. Angular stellardiameters range from 0.6 mas to 1.8 mas (median is 1.1 mas) with amedian precision of 1.35%. For both the northern and southernhemispheres, the closest calibrator star is always less than 10°away.
| CHARM2: An updated Catalog of High Angular Resolution Measurements
We present an update of the Catalog of High Angular ResolutionMeasurements (CHARM, Richichi & Percheron \cite{CHARM}, A&A,386, 492), which includes results available until July 2004. CHARM2 is acompilation of direct measurements by high angular resolution methods,as well as indirect estimates of stellar diameters. Its main goal is toprovide a reference list of sources which can be used for calibrationand verification observations with long-baseline optical and near-IRinterferometers. Single and binary stars are included, as are complexobjects from circumstellar shells to extragalactic sources. The presentupdate provides an increase of almost a factor of two over the previousedition. Additionally, it includes several corrections and improvements,as well as a cross-check with the valuable public release observationsof the ESO Very Large Telescope Interferometer (VLTI). A total of 8231entries for 3238 unique sources are now present in CHARM2. Thisrepresents an increase of a factor of 3.4 and 2.0, respectively, overthe contents of the previous version of CHARM.The catalog is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/431/773
| Hipparcos red stars in the HpV_T2 and V I_C systems
For Hipparcos M, S, and C spectral type stars, we provide calibratedinstantaneous (epoch) Cousins V - I color indices using newly derivedHpV_T2 photometry. Three new sets of ground-based Cousins V I data havebeen obtained for more than 170 carbon and red M giants. These datasetsin combination with the published sources of V I photometry served toobtain the calibration curves linking Hipparcos/Tycho Hp-V_T2 with theCousins V - I index. In total, 321 carbon stars and 4464 M- and S-typestars have new V - I indices. The standard error of the mean V - I isabout 0.1 mag or better down to Hp~9 although it deteriorates rapidly atfainter magnitudes. These V - I indices can be used to verify thepublished Hipparcos V - I color indices. Thus, we have identified ahandful of new cases where, instead of the real target, a random fieldstar has been observed. A considerable fraction of the DMSA/C and DMSA/Vsolutions for red stars appear not to be warranted. Most likely suchspurious solutions may originate from usage of a heavily biased color inthe astrometric processing.Based on observations from the Hipparcos astrometric satellite operatedby the European Space Agency (ESA 1997).}\fnmsep\thanks{Table 7 is onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/397/997
| Galactic bulge M giants. III - Near-infrared spectra and implications for the stellar content of E and S0 galaxies
Spectra at 0.6-0.9 micron of 320 K and M giants in six low-absorptionfields along the minor axis of the galactic bulge and of an additional60 late-type giants and dwarfs in the solar neighborhood were obtained.Indices of the strength of molecular absorption are combined withprevious infrared and optical photometry to estimate the mean metalabundance of the bulge M giants and to constrain the relativecontribution of late giants and dwarfs to the integrated light of E andS0 galaxies.
| M giants in Baade's window - Infrared colors, luminosities, and implications for the stellar content of E and S0 galaxies
In this paper, 1-10 micron photometric observations of M giants inBaade's window are presented and interpreted. When compared to solarneighborhood M giants, it is found that: (1) bulge giants at the samespectral type have bluer JHK colors but stronger CO indices; (2) thenearly dispersionless H-H, H-K relation for the bulge giants lies on theopposite side of the mean field giant relation from that for globularcluster stars; and (3) bulge M giants are up to two magnitudes fainterthan field giants of the same spectral type, and their luminosityfunction drops precipitously for M(bol) brighter than -4.2. It is arguedthat the near-infrared energy distribution of the bulge giants isstrongly affected by molecular blanketing, particularly from H2O.Long-period variables have infrared colors and indices which give themphotometric properties distinct form all other M giants in Baade'swindow. The observed characteristics of the bulge M giants areconsistent with their being representatives of a population with ametallicity considerably in excess of solar.
|
Добавить новую статью
Внешние ссылки
- - Внешних ссылок не найдено -
Добавить внешнюю ссылку
Группы:
|
Наблюдательные данные и астрометрия
| Созвездие: | Гидра |
| Прямое восхождение: | 11h39m45.48s |
| Склонение: | -34°58'55.3" |
| Видимая звёздная величина: | 7.471 |
| Расстояние: | 584.795 парсек |
| Собственное движение RA: | 3.6 |
| Собственное движение Dec: | -7.2 |
| B-T magnitude: | 9.633 |
| V-T magnitude: | 7.65 |
Каталоги и обозначения:
|
INHABITED SKY
