Садржај
Слике
Уплоадјуј своје слике
DSS Images Other Images
Везани чланци
Effective temperature scale and bolometric corrections from 2MASS photometry
We present a method to determine effective temperatures, angularsemi-diameters and bolometric corrections for population I and II FGKtype stars based on V and 2MASS IR photometry. Accurate calibration isaccomplished by using a sample of solar analogues, whose averagetemperature is assumed to be equal to the solar effective temperature of5777 K. By taking into account all possible sources of error we estimateassociated uncertainties to better than 1% in effective temperature andin the range 1.0-2.5% in angular semi-diameter for unreddened stars.Comparison of our new temperatures with other determinations extractedfrom the literature indicates, in general, remarkably good agreement.These results suggest that the effective temperaure scale of FGK starsis currently established with an accuracy better than 0.5%-1%. Theapplication of the method to a sample of 10 999 dwarfs in the Hipparcoscatalogue allows us to define temperature and bolometric correction (Kband) calibrations as a function of (V-K), [m/H] and log g. Bolometriccorrections in the V and K bands as a function of T_eff, [m/H] and log gare also given. We provide effective temperatures, angularsemi-diameters, radii and bolometric corrections in the V and K bandsfor the 10 999 FGK stars in our sample with the correspondinguncertainties.
| The POINT-AGAPE Survey - I. The variable stars in M31
For the purposes of identifying microlensing events, the POINT-AGAPEcollaboration has been monitoring the Andromeda galaxy (M31) for threeseasons (1999-2001) with the Wide Field Camera on the Isaac NewtonTelescope. In each season, data are taken for one hour per night forroughly 60 nights during the six months that M31 is visible. The two 33× 33 arcmin2 fields of view straddle the central bulge,northwards and southwards. We have calculated the locations, periods andbrightness of 35 414 variable stars in M31 as a by-product of themicrolensing search. The variables are classified according to theirperiod and brightness. Rough correspondences with classical types ofvariable star (such as Population I and II Cepheids, Miras andsemiregular long-period variables) are established. The spatialdistribution of Population I Cepheids is clearly associated with thespiral arms, while the central concentration of the Miras andlong-period variables varies noticeably, the brighter and the shorterperiod Miras being much more centrally concentrated.A crucial role in the microlensing experiment is played by the asymmetrysignal - the excess of events expected in the southern or more distantfields as measured against those in the northern or nearer fields. Itwas initially assumed that the variable star populations in M31 would besymmetric with respect to the major axis, and thus variable stars wouldnot be a serious contaminant for measuring the microlensing asymmetrysignal. We demonstrate that this assumption is not correct. All thevariable star distributions are asymmetric primarily because of theeffects of differential extinction associated with the dust lanes. Thesize and direction of the asymmetry of the variable stars is measured asa function of period and brightness. The implications of this discoveryfor the successful completion of the microlensing experiments towardsM31 are discussed.
| 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
| Photometry of symbiotic stars. X. EG And, Z And, BF Cyg, CH Cyg, V1329 Cyg, AG Dra, RW Hya, AX Per and IV Vir
We present new photometric observations of EG And, Z And, BF Cyg, CHCyg, V1329 Cyg, AG Dra, RW Hya, AX Per and IV Vir made in the standardJohnson UBVR system. The current issue summarizes observations of theseobjects to 2001 December. The main results can be summarized as follows:EG And: A periodic double-wave variation in all bands as a function ofthe orbital phase was confirmed. A maximum of the light changes wasobserved in U (Delta U ~ 0.5 mag). Z And: Our observations cover anactive phase, which peaked around 8.4 in U at the beginning of 2000December. Consequently, a gradual decrease in the star's brightness hasbeen observed. BF Cyg: A periodic wave-like variation in the opticalcontinuum reflects a quiescent phase of this star. A complex light curve(LC) profile was observed. CH Cyg: The recent episode of activity endedin Spring 2000. We determined the position of an eclipse in the outerbinary at JD 2451426 +/- 3. Recent observations indicate a slow increasein the star's brightness. V1329 Cyg: Observations were made around amaximum at 2001.2. AG Dra: Our measurements from the Autumn of 2001revealed a new eruption, which peaked at ~JD 2452217. RW Hya: The lightminimum in our mean visual LC precedes the time of the spectroscopicconjunction of the giant in the binary. AX Per: A periodic wave-likevariation was observed. Our recent observations revealed a secondaryminimum at the orbital phase 0.5, seen best in the V and B bands. IVVir: The LC displays a double-wave throughout the orbital cycle.
| Observations of Galaxies with the Midcourse Space Experiment
We have imaged eight nearby spiral galaxies with the SPIRIT III infraredtelescope on the Midcourse Space Experiment (MSX) satellite in themid-infrared at 18" resolution at 8.3, 12.1, 14.7, and 21.3 μm. Eachof the eight shows interesting structure not previously detected witholder, lower resolution infrared data sets, such as a resolved nucleusor spiral structure. The MSX data are compared with existing data setsat ultraviolet, optical, and infrared wavelengths, including recentobservations from the Infrared Space Observatory. The infraredstructures in M83 and NGC 5055 show a striking similarity to theultraviolet emission but are less similar to the optical emission.Several point sources with no identified counterparts at otherwavelengths are found near M31, NGC 4945, M83, and M101. Over 200previously known objects are also detected at 8 μm.
| HIPPARCOS age-metallicity relation of the solar neighbourhood disc stars
We derive age-metallicity relations (AMRs) and orbital parameters forthe 1658 solar neighbourhood stars to which accurate distances aremeasured by the HIPPARCOS satellite. The sample stars comprise 1382 thindisc stars, 229 thick disc stars, and 47 halo stars according to theirorbital parameters. We find a considerable scatter for thin disc AMRalong the one-zone Galactic chemical evolution (GCE) model. Orbits andmetallicities of thin disc stars show now clear relation each other. Thescatter along the AMR exists even if the stars with the same orbits areselected. We examine simple extension of one-zone GCE models whichaccount for inhomogeneity in the effective yield and inhomogeneous starformation rate in the Galaxy. Both extensions of the one-zone GCE modelcannot account for the scatter in age - [Fe/H] - [Ca/Fe] relationsimultaneously. We conclude, therefore, that the scatter along the thindisc AMR is an essential feature in the formation and evolution of theGalaxy. The AMR for thick disc stars shows that the star formationterminated 8 Gyr ago in the thick disc. As already reported by Grattonet al. (\cite{Gratton_et.al.2000}) and Prochaska et al.(\cite{Prochaska_et.al.2000}), thick disc stars are more Ca-rich thanthin disc stars with the same [Fe/H]. We find that thick disc stars showa vertical abundance gradient. These three facts, the AMR, verticalgradient, and [Ca/Fe]-[Fe/H] relation, support monolithic collapseand/or accretion of satellite dwarf galaxies as likely thick discformation scenarios. Tables 2 and 3 are only available in electronicform at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)or via http:/ /cdsweb.u-strasbg.fr/ cgi-bin/qcat?J/ A+A/394/927
| Long-Term VRI Photometry of Small-Amplitude Red Variables. I. Light Curves and Periods
We report up to 5000 days of VRI photometry, from a robotic photometrictelescope, of 34 pulsating red giants, namely, TV Psc, EG And, Z Psc, RZAnd, 4 Ori, RX Lep, UW Lyn, η Gem, μ Gem, ψ1 Aur,V523 Mon, V614 Mon, HD 52690, Y Lyn, BC CMi, X Cnc, UX Lyn, RS Cnc, VYUMa, ST UMa, TU CVn, FS Com, SW Vir, 30 Her, α1 Her,V642 Her, R Lyr, V450 Aql, V1293 Aql, δ Sge, EU Del, V1070 Cyg, WCyg, and μ Cep, as well as a few variable comparison stars. V, R, andI variations are generally in phase. The length and density of the dataenable us to look for variations on timescales ranging from days toyears. We use both power-spectrum (Fourier) analysis and autocorrelationanalysis, as well as light-curve analysis; these three approaches arecomplementary. The variations range from regular to irregular, but inmost of the stars, we find a period in the range of 20-200 days, whichis probably due to low-order radial pulsation. In many of the stars, wealso find a period which is an order of magnitude longer. It may be dueto rotation, or it may be due to a new kind of convectively inducedoscillatory thermal mode, recently proposed by P. Wood.
| The second ROSAT PSPC survey of M 31 and the complete ROSAT PSPC source list
This paper reports the results of the analysis of the second ROSAT PSPCsurvey of M 31 performed in summer 1992. We compare our results withthose of the first survey, already published in Supper et al.(\cite{Sup97}). Within the ~ 10.7 deg2 field of view, 396individual X-ray sources are detected in the second survey data, ofwhich 164 are new detections. When combined with the first survey, thisresult in a total of 560 X-ray sources in the field of M 31. Their (0.1keV-2.0 keV) fluxes range from 7x 10-15 erg cm-2s-1 to 7.6x 10-12 erg cm-2s-1, and of these 560 sources, 55 are tentatively identifiedwith foreground stars, 33 with globular clusters, 16 with supernovaremnants, and 10 with radio sources and galaxies (including M 32). Acomparison with the results of the Einstein M 31 survey reveals 491newly detected sources, 11 long term variable sources, and 7 possibletransient sources. Comparing the two ROSAT surveys, we come up with 34long term variable sources and 8 transient candidates. For the M 31sources, the observed luminosities range from 4x 1035 ergs-1 to 4x 1038 erg s-1. The total (0.1keV-2.0 keV) luminosity of M 31 is (3.4+/-0.3)x 1039 ergs-1, distributed approximately equally between the bulge anddisk. Within the bulge region, the luminosity of a possible diffusecomponent combined with faint sources below the detection threshold is(2.0+/-0.5)x 1038 erg s-1. An explanation in termsof hot gaseous emission leads to a maximum total gas mass of(1.0+/-0.3)x 106 Msun. Tables 5, 6, 7 are alsoavailable 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/373/63
| Mesures de vitesses radiales. VIII. Accompagnement AU sol DU programme d'observation DU satellite HIPPARCOS
We publish 1879 radial velocities of stars distributed in 105 fields of4^{\circ} \times 4^{\circ}. We continue the PPO series \cite[(Fehrenbachet al. 1987;]{Feh87} \cite[Duflot et al. 1990, 1992 and 1995),]{Du90}using the Fehrenbach objective prism method. Table 1 only available inelectronic form at CDS via to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Is the symbiotic binary EG And an eclipsing system?
We present all available UBV photometry of the symbiotic binary EG Andobtained during the last 10-years. The light curves display a doublewave through one orbital cycle. It is shown that this behaviour cannotbe explained by eclipses of the two detached sources of the continuumradiation. The present models of EG And are not able to simulatesatisfactorily variation in both the far ultraviolet and the opticalcontinuum.
| ROSAT PSPC survey of M 31.
This paper reports on results of the analysis of the first M 31 surveywith the ROSAT PSPC performed in July 1991. Within the =~6.3deg^2^ fieldof view we detected 396 individual X-ray sources with (0.1keV-2.4keV)fluxes ranging from =~5x10^-15^erg/cm^2^/s^ to =~4x10^-12^erg/cm^2^/s.Of these 396 sources, 43 have been tentatively identified withforeground stars, 29 with globular clusters, 17 with supernova remnants,3 with other galaxies (including M 32), and 3 with radio sources. Adetailed analysis of the integral flux distribution of the sources showsthat approximately one fifth are likely to be background objects. Bycomparison with the results of the Einstein M 31 survey, we find 327newly detected sources, 15 moderately variable sources, 3 bright and 6faint possible transient sources. For those sources in M 31, theobserved luminosities range from =~3x10^35^erg/s to =~2x10^38^erg/s (at690kpc). The total (0.1keV-2.4keV) luminosity of M 31 is(2.9+/-0.3)x10^39^ erg/s, roughly one third of which is from the bulgeand two thirds of which are from the disk. The luminosity of a diffusecomponent within the bulge region is estimated to be less than3.2x10^38^erg/s. An explanation in terms of hot gaseous emission leadsto a maximum total gas mass of 1.7x10^6^Msun_. We find thatthe integral luminosity distribution of sources associated with globularclusters is similar to that of the Milky Way. Finally, the results ofspectral fits to 56 of the brightest sources are discussed; we classify15 objects as "supersoft sources" according to their spectralcharacteristics.
| Photoelectric UBV observations of EG Andromedae
Not Available
| A catalogue of the brightest stars in the field of M31
A catalog of 11438 stars in the field of M31 has been compiled usingTautenburg Schmidt plates in U, B, V, and R. The scanning and datareduction methods are discussed along with the photometric calibrationapplied. The present catalog is complete to about 18.0 mag in U, about19.2 mag in B, about 18.8 mag in V, and about 17.8 mag in R. Thequestion of membership to M31 is considered.
| Photoelectric Observations of the Symbiotic Binary EG Andromedae
Not Available
| S Andromedae 1885 - A centennial review
The definitive light curve presented for the 1885 S And supernova in M31is based on a reduction of 40 comparison stars to the V system.Prediscovery observations are reexamined, and evidence for and againstclassification as a Type I supernova is discussed. Except for theunusual color noted near maximum, the color-luminosity evolution matchesthat of typical Type I supernovae. Spectral observations, whilemarginal, are found to be in good agreement and to show that mostextinction maxima can be identified with the main lines of typical TypeI supernovae.
| A magnitude limited stellar X-ray survey and the F star X-ray luminosity function
An X-ray survey has been conducted of stars brighter than visualmagnitude 8.5 that have serendipitously fallen into the fields of viewof the Imaging Proportional Counter of the Einstein Observatory. Thesurvey includes 227 separate 1 x 1 deg fields, containing 274 stars witha visual magnitude of no more than 8.5 and covering a wide range ofspectral types and luminosity classes. X-ray emission was detected from33 stars, and upper limits have been determined for the remainder of thesample. F type stars dominate the detected sample, and most of these areshown to be dwarfs. An X-ray luminosity function for dF stars has beendeduced, and reveals that the average 0.2-4.0 keV luminosity of thesestars is around 10 to the 29th erg/sec. Constraints have been placed onthe high luminosity tails and medians of the X-ray luminosity functionsfor other types of stars.
| A photometric map of interstellar reddening within 100 PC
Color excesses and distances are calculated for 300 bright, northern,late F stars using uvby beta photometric indices. The data allow anextension of the earlier maps by Perry and Johnston of the spatialdistribution of interstellar reddening into the local (r less than 100pc) solar neighborhood. Some definite conclusions are made regarding thedistribution of interstellar dust in the northern hemisphere and within300 pc of the sun by merging these results and the polarimetricobservations by Tinbergen (1982) for 180 stars within 35 pc of the sun.
| The fourth meridian catalog of Besancon Observatory
The catalog presented gives differential meridian positions for 670F-type stars between plus 15 and plus 45 deg declination. The positionsare reduced to the equinox of 1950.0 without proper motions; 333 FK4stars were used as reference stars. A minimum of three and an average offive transits of each program star were observed photoelectrically usinga Gautier transit circle and a Hog grid. The internal accuracy ofindividual measurements is shown to range from 0.013 sec in rightascension and 0.30 arcsec in declination for brighter stars under betterobserving conditions to 0.020 sec in right ascension and 0.38 arcsec indeclination for fainter stars under worse conditions. The standarderrors were applied to compute weighted mean positions, mean epochs, andunweighted means for the program stars. Mean corrections for 283 FK4stars are also provided.
| Results from an extensive Einstein stellar survey
The preliminary results of the Einstein Observatory stellar X-ray surveyare presented. To date, 143 soft X-ray sources have been identified withstellar counterparts, leaving no doubt that stars in general constitutea pervasive class of low-luminosity galactic X-ray sources. Stars alongthe entire main sequence, of all luminosity classes, pre-main sequencestars as well as very evolved stars have been detected. Early type OBstars have X-ray luminosities in the range 10 to the 31st to 10 to the34th ergs/s; late type stars show a somewhat lower range of X-rayemission levels, from 10 to the 26th to 10 to the 31st ergs/s. Late typemain-sequence stars show little dependence of X-ray emission levels uponstellar effective temperature; similarly, the observations suggest weak,if any, dependence of X-ray luminosity upon effective gravity. Instead,the data show a broad range of emission levels (about three orders ofmagnitude) throughout the main sequence later than F0.
| A peculiar nova in M31
A stellar-like object with a B magnitude of 16.3 has been discoverednear a spiral arm of the galaxy M31. It was equally bright in a red bandcentered at 6725 A. Eight days later it was still bright in H-alpha butmuch fainter (m approximately 20) in a wide band centered at 5500 A. TheB luminosity dropped by about 4 mag in a month. The object was notpresent on blue photographs of M31 taken during the past 10 yr. Thephotometric data and a spectrum obtained with the 200-inch SITspectrograph after its decline suggest an anomalous novalike object.
| A catalogue of four-color photometry of late F-type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969AJ.....74..705P&db_key=AST
| Stellar Associations in the Andromeda Nebula.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1964ApJS....9...65V&db_key=AST
| Five-color photometry of variable star field IV in M31
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1964AJ.....69..610V&db_key=AST
|
Додај нови чланак
Линкови у сродству са темом
Додај нови линк
Чланови следећих група \:
|
Посматрања и Астрометриски подаци
| Сазвежђа: | Андромеда |
| Ректацензија: | 00h42m01.43s |
| Deклинација: | +40°41'17.7" |
| Apparent магнитуда: | 7.034 |
| Даљина: | 49.068 parsecs |
| Proper motion RA: | -11.6 |
| Proper motion Dec: | -63.3 |
| B-T magnitude: | 7.576 |
| V-T magnitude: | 7.079 |
Каталог и designations:
|
INHABITED SKY
