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מאמרים קשורים
The supermassive black hole of FornaxA
The radio galaxy FornaxA (NGC 1316) is a prominent merger remnant in theoutskirts of the Fornax cluster. Its giant radio lobes suggest thepresence of a powerful active galactic nuclei (AGN) and thus a centralsupermassive black hole (SMBH). FornaxA now seems to be in a transitionstate between active black hole growth and quiescence, as indicated bythe strongly declined activity of the nucleus. Studying objects in thisevolutionary phase is particularly important in order to understand thelink between bulge formation and black hole growth, which is manifestedin the M•-? relation between black hole mass andbulge velocity dispersion. So far, a measurement of the SMBH mass hasnot been possible in FornaxA, as it is enshrouded in dust which makesoptical measurements impossible. We present high-resolution adaptiveoptics assisted integral-field data of FornaxA, taken with SINFONI atthe Very Large Telescope in the K band, where the influence of dust isnegligible. The achieved spatial resolution is 0.085 arcsec, which isabout a fifth of the diameter of the expected sphere of influence of theblack hole. The stellar kinematics was measured using the region aroundthe CO bandheads at 2.3 ?m. FornaxA does not rotate inside the inner~3 arcsec. The velocity dispersion increases towards the centre. Theweak AGN emission affects the stellar kinematics in the inner ~0.06arcsec only. Beyond this radius, the stellar kinematics appears relaxedin the central regions. We use axisymmetric orbit models to determinethe mass of the SMBH in the centre of FornaxA. The three-dimensionalnature of our data provides the possibility to directly test theconsistency of the data with axisymmetry by modelling each of the fourquadrants separately. According to our dynamical models, consistent SMBHmasses M• and dynamical Ks-band mass-to-lightratios ? are obtained for all quadrants, with = 1.3 × 108Msolar[rms(M•) = 0.4 × 108Msolar]and = 0.68 [rms(?) = 0.03], confirming theassumption of axisymmetry. For the folded and averaged data, we findM• = 1.5+0.75-0.8 ×108Msolar and ? =0.65+0.075-0.05 (3? errors). Thus, the blackhole mass of FornaxA is consistent within the error with the Tremaine etal. M•-? relation, but is a factor of ~4 smallerthan expected from its bulge mass and the Marconi & Hunt relation.Based on observations at the European Southern Observatory (ESO) VeryLarge Telescope [076.B-0457(A)] and archival ESO La Silla [66.C-0310(A)]and NASA/ESA Hubble Space Telescope data (GO Proposal 7458), obtainedfrom the ESO/ST-ECF Science Archive Facility.E-mail: nnowak@mpe.mpg.de
| Absolute magnitudes of carbon stars from HIPPARCOS parallaxes
Hipparcos trigonometric parallaxes and photometric data for about 40bright carbon stars have been analysed. Individual absolute visual andbolometric magnitudes, normal color indices (B-V)_0, absorption valuesand distance moduli were determined. By comparison with stellarevolutionary tracks for initial mass 1<= M/M_ȯ<=4 it is foundthat the majority of CH- and R-stars are on the giant and subgiantbranches, but N-stars occupy a region -4
| 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.
| Longterm Photometry of Variables at ESO - Part Two - the Second Data Catalogue 1986-1990
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&AS..102...79S&db_key=AST
| Evolved GK stars near the sun. I - The old disk population
A sample of nearly two thousand GK giants with intermediate band, (R,I),DDO and Geneva photometry has been assembled. Astrometric data is alsoavailable for most of the stars. The some 800 members of the old diskpopulation in the sample yield accurate luminosities (from two sources),reddening values and chemical abundances from calibrations of thephotometric parameters. Less than one percent of the objects arepeculiar in the sense that the flux distribution is abnormal. Thepeculiarity is signaled by strong CH (and Ba II) and weak CH. The CH+stars are all spectroscopic binaries, probably with white dwarfcompanions, whereas the CH- stars are not. A broad absorption band,centered near 3500 A, is found in the CH+ stars whereas the CH- objectshave a broad emission feature in the same region. The intensity of theseabsorptions and emissions are independent of the intensity of abnormalspectral features. Ten percent of the old disk sample have a heavyelement abundance from one and a half to three times the solar value.The distribution of the heavy element abundances is nearly a normal onewith a peak near solar abundance and ranges three times to one sixthsolar. The distribution of the (U, V) velocities is independent of theheavy element abundance and does not appear to be random. Ten percent ofthe old disk stars show a CN anomaly, equally divided between CN strongand CN weak. Several stars of individual astrometric or astrophysicalimportance are isolated.
| Long-term photometry of variables at ESO. I - The first data catalogue (1982-1986)
This paper presents the catalog of photometric data in the Stromgrensystem obtained during the first four years (October 1982 - September1986) of the Long-Term Photometry of Variables (LTPV) program at ESO.The data are available in computer-readable form.
| The Perkins catalog of revised MK types for the cooler stars
A catalog is presented listing the spectral types of the G, K, M, and Sstars that have been classified at the Perkins Observatory in therevised MK system. Extensive comparisons have been made to ensureconsistency between the MK spectral types of stars in the Northern andSouthern Hemispheres. Different classification spectrograms have beengradually improved in spite of some inherent limitations. In thecatalog, the full subclasses used are the following: G0, G5, G8, K0, K1,K2, K3, K4, K5, M0, M1, M2, M3, M4, M5, M6, M7, and M8. Theirregularities are the price paid for keeping the general scheme of theoriginal Henry Draper classification.
| Large and Kinematically Unbiased Samples of G- and K-Type Stars. III. Evolved Young Disk Stars in the Bright Star Sample
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1989PASP..101...54E&db_key=AST
| Revised MK spectral types for G, K, and M stars
A catalog of spectral types of 552 G, K, and M stars is presented, whichis classified on the revised MK system. Stellar representatives of thehalo, disk, and arm populations in all parts of the sky are included.Photoelectric V magnitudes are given, as are intensity estimates of anyfeatures which make the spectrum appear peculiar as compared to thespectrum of a similar normal star. Abundance indices are also providedin the following lines or bands: CN, barium, Fe, calcium, and CH.
| A photoelectric measurement of magnesium for late-type stars
A photoelectric index of MgH + Mg b for late-type stars has been createdby the addition of one filter bandpass to the DDO system. Measurementsshow that this index has good sensitivity to surface gravity for Kstars, and suggest that it can differentiate metal-poor halo giants fromdisk stars. From this index, involving measurement through two filtersalone, it appears that membership can be determined for stars on thegiant branch of globular clusters. It is possible that the index couldbe used, after calibration with cluster giants, to determine ages ofgiant stars in the field.
| Four-color photometry of marginal barium stars
Photometric observations in the Stromgren uvby system are reported for15 marginal barium stars, four classical barium stars, nine strontiumstars, and about 20 normal giants (for comparison). Plots of c1 indexvs. (b-y) and of Ba/Fe abundance ratio vs. delta c1 are presented forthe observed stars. It is found that the marginal barium stars exhibit adecrease of 0 to 0.1 mag in c1, which is possibly correlated with thedegree of s-process element enrichment, and that some stars may show asmall degree of s-process enrichment without a corresponding decrease inc1 index. The results indicate that while four-color photometry isuseful in discriminating classical barium stars from normal giants, themarginal barium stars are not necessarily separated from normal stars inthe c1 vs. (b-y) diagram.
| A carbon star in NGC 2477.
Abstract image available at:http://adsabs.harvard.edu/abs/1973MNRAS.164P..11C
| The classification of intrinsic variable stars. I. The red variables of type N
Abstract image available at:http://adsabs.harvard.edu/abs/1972ApJ...174...45E
| Narrow-and broad-band photometry of red stars. VI. Luminosities and temperatures for old disk-population red stars of high luminosity
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971ApJ...165..317E&db_key=AST
| The Absolute Magnitudes of Carbon Stars
Not Available
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הכנס מאמר חדש
לינקים קשורים
הכנס לינק חדש
משמש של הקבוצה הבאה
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | מצפן |
| התרוממות ימנית: | 08h46m34.96s |
| סירוב: | -29°45'30.0" |
| גודל גלוי: | 7.618 |
| מרחק: | 10000000 פארסק |
| תנועה נכונה: | -4.8 |
| תנועה נכונה: | 1.8 |
| B-T magnitude: | 9.535 |
| V-T magnitude: | 7.777 |
קטלוגים וכינוים:
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