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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.
| Speckle Interferometry at the US Naval Observatory. VIII.
The results of 2044 speckle interferometric observations of doublestars, made with the 26 inch (66 cm) refractor of the US NavalObservatory, are presented. Each speckle interferometric observation ofa system represents a combination of over a thousand short-exposureimages. These observations are averaged into 1399 mean positions andrange in separation from 0.16" to 14.97", with a mean separation of2.51". This is the eighth in a series of papers presenting measuresobtained with this system and covers the period 2001 March 18 through2001 December 30.
| 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
| The M31 population of supersoft sources
The 1991 ROSAT PSPC M31 X-ray point source catalog has been screened inorder to set up a sample of candidate supersoft sources in this galaxy,additional to the 16 supersoft sources already known in M31 (Supper etal. 1997). Selection criteria used were based on hardness ratios(``X-ray colors''), as developed in an earlier paper (Kahabka 1998). Anadditional criterion to be fulfilled was that the observed count rate isin agreement with the expected steady-state luminosity for a source withthese hardness ratios. This condition constrained mainly the hydrogenabsorbing column towards the source. 26 candidates not correlating withforeground stars and M31 supernova remnants have been found to fulfilone of the selection criteria. They can be considered to be candidatesupersoft sources in M31. This comprises 6% of all point sources in thisgalaxy. For these candidates absorbing hydrogen column densities,effective temperatures and white dwarf masses (assuming the sources areon the stability line of surface nuclear burning) are derived. Anobserved white dwarf mass distribution is derived which indicates thatthe masses are constrained to M~gt 0.90 \ Msun. The entirepopulation of supersoft sources in M31 is estimated taking a theoreticalwhite dwarf mass distribution into account and under the assumption thatthe observationally derived sample is restricted to white dwarf massesabove 0.90\ Msun. Taking into account that the gas and thesource population have different scale heights a total number of atleast 200-500 and at most 6,000-15,000 sources is deduced (depending onthe used galaxy N_H model), making use of the population synthesiscalculation of Yungelson et al. (1996). The spatial distribution favorsa disk (or spiral-arm) dominated young stellar population with a ratioof 1/(4-7) of bulge/disk systems, very similar to what has been foundfor novae in the Milky Way but lower than favored for novae in M31 ( ~1/2). Supersoft sources and Cepheids both show association with the M31spiral arms and may belong to a younger stellar population. A mean spacedensity of ~ (0.1-5)x 10(-8) \ pc(-3) is inferred for the supersoftsources. Assuming that all supersoft sources with masses in excess of0.5\ Msun are progenitors of supernovae of type Ia, a SN Iarate of (0.8-7)x 10(-3) \ yr(-1) is derived for M31 based on theseprogenitors. Supersoft sources might be able to account for 20-100% ofthe total SN Ia rate in a galaxy like M31.
| 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.
| A preliminary compilation of DS-programme star positions
A catalog is presented of the double-star-program (DS-program) starpositions, listing right ascensions for 930 DSs and declinations for1225 DSs of the program. The positions were compiled from the observedvalues obtained between 1980 and 1987 with the meridian circles of sixUSSR observatories (the Moscow, Kazan', Kiev, Khar'kov, Odessa, andTashkent Observatories) and the Belgrade Observatory. The measurementsand the treatment of the observational material were performed using therelative method, and the FK-4 system stars were used as reference stars.
| Micrometer observations of double stars.8.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975ApJS...29..315H&db_key=AST
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| Takýmyýldýz: | Zincirli Prenses |
| Sað Açýklýk: | 00h47m03.23s |
| Yükselim: | +41°57'53.4" |
| Görünürdeki Parlaklýk: | 9.026 |
| Uzaklýk: | 176.991 parsek |
| özdevim Sað Açýklýk: | -2.8 |
| özdevim Yükselim: | 25.3 |
| B-T magnitude: | 9.423 |
| V-T magnitude: | 9.059 |
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