Contenidos
Imágenes
Subir su imagen
DSS Images Other Images
Artículos relacionados
Further observations of Hipparcos red stars and standards for UBV(RI)C photometry
We present homogeneous and standardized UBV(RI)C JHKphotometry for over 100 M stars selected from an earlier paper on thebasis of apparent photometric constancy. L photometry has been obtainedfor stars brighter than about L = 6. Most of the stars have asubstantial number of UBV(RI)C observations and, it is hoped,will prove useful as red supplementary standards. Additionally, we listJHK photometry for nearly 300 Hipparcos red stars not selected asstandards, as well as L photometry for the brightest stars.
| Chemically Tagging the HR 1614 Moving Group
We present abundances for a sample of F, G, and K dwarfs of the HR 1614moving group based on high-resolution, high signal-to-noise ratiospectra from the Anglo-Australian Telescope UCLES instrument. Our sampleincludes stars from Feltzing and Holmberg, as well as from Eggen.Abundances were derived for Na, Mg, Al, Si, Ca, Mn, Fe, Ni, Zr, Ba, Ce,Nd, and Eu. The α, Fe, and Fe-peak element abundances show abimodal distribution, with four stars having solar metallicities, whilethe remaining 14 stars are metal-rich, [Fe/H]>=0.25 dex. However, theabundances of these two groups converge for the heavier n-captureelements. Based on their photometry and kinematics, three of the fourdeviating stars are likely nonmembers or binaries. Although one starcannot be excluded on these grounds, we do expect low-levelcontamination from field stars within the HR 1614 moving group's rangeof magnitude, color, and space velocities. Disregarding these fourstars, the abundance scatter across the group members for all elementsis low. We find that there is an 80% probability that the intrinsicscatter does not exceed the following values: Fe, 0.01 dex; Na, 0.08dex; Mg, 0.02 dex; Al, 0.06 dex; Si, 0.02 dex; Ca, 0.02 dex; Mn, 0.01dex; Ni, 0.01 dex; Zr, 0.03 dex; Ba, 0.03 dex; Ce, 0.04 dex; Nd, 0.01dex; and Eu, 0.02 dex. The homogeneity of the HR 1614 group in age andabundance suggests that it is the remnant of a dispersed star-formingevent. Its kinematical coherence shows that such a dispersing systemneed not be significantly perturbed by external dynamical influencessuch as Galactic spiral structure or giant molecular clouds, at leastover a period of 2 Gyr.
| The central kinematics of NGC 1399 measured with 14 pc resolution
We present near-infrared (NIR) adaptive optics-assisted spectroscopicobservations of the CO(Δμ= 2) absorption bands towards thecentre of the giant elliptical galaxy NGC 1399. The observations weremade with NAOS-CONICA (on the European Southern Observatory's Very LargeTelescope) and have a full width at half-maximum resolution of0.15arcsec (14pc). Kinematic analysis of the observations reveals adecoupled core and strongly non-Gaussian line-of-sight velocity profilesin the central 0.2arcsec (19pc). NIR imaging also indicates anasymmetric elongation of the central isophotes in the same region.We use spherical orbit-superposition models to interpret the kinematics,using a set of orthogonal `eigen-velocity profiles' that allow us to fitmodels directly to spectra. The models require a central black hole ofmass 1.2+0.5-0.6× 109Msolar, with a strongly tangentially biased orbitdistribution in the inner 40pc.
| 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
| UBV(RI)C photometry of Hipparcos red stars
We present homogeneous and standardized UBV(RI)C photometryfor nearly 550 M stars selected from the Hipparcos satellite data baseusing the following selection criteria: lack of obvious variability (noHipparcos variability flag); δ<+10°(V-I)>1.7 and Vmagnitude fainter than about 7.6. Comparisons are made between thecurrent photometry, other ground-based data sets and Hipparcosphotometry. We use linear discriminant analysis to determine aluminosity segregation criterion for late-type stars, and principalcomponent analysis to study the statistical structure of the colourindices and to calibrate absolute magnitude in terms of (V-I) for thedwarf stars. Various methods are used to determine the mean absolutemagnitude of the giant stars. We find 10 dwarf stars, apparentlypreviously unrecognized (prior to Hipparcos) as being within 25pc,including five within 20pc.
| SANTIAGO 91, a right ascension catalogue of 3387 stars (equinox J2000).
The positions in right ascension of 3387 stars belonging to the Santiago67 Catalogue, observed with the Repsold Meridian Circle at Cerro Calan,National Astronomical Observatory, during the period 1989 to 1994, aregiven. The average mean square error of a position, for the wholeCatalogue, is +/-0.009 s. The mean epoch of the catalogue is 1991.84.
|
Enviar un nuevo artículo
Enlaces relacionados
- - No se han encontrado enlaces -
En viar un nuevo enlace
Miembro de los siguientes grupos:
|
Datos observacionales y astrométricos
| Constelación: | Erídano |
| Ascensión Recta: | 04h04m27.45s |
| Declinación: | -34°44'07.3" |
| Magnitud Aparente: | 8.642 |
| Distancia: | 10000000 parsecs |
| Movimiento Propio en Ascensión Recta: | 3.8 |
| Movimiento Propio en Declinación: | 0 |
| B-T magnitude: | 10.595 |
| V-T magnitude: | 8.804 |
Catálogos y designaciones:
|
