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Near-Infrared Spectroscopy of 0.4 < z < 1.0 CFRS Galaxies: Oxygen Abundances, SFRs, and Dust
Using new J-band VLT ISAAC and Keck NIRSPEC spectroscopy, we havemeasured Hα and [N II] λ6584 line fluxes for0.470.1 for most (but not all) of the CFRSgalaxies indicate that they lie on the high-metallicity branch of theR23 calibration; (4) about one-third of the 0.47
| L' and M' standard stars for the Mauna Kea Observatories Near-Infrared system
We present L' and M' photometry, obtained at the United Kingdom InfraredTelescope (UKIRT) using the Mauna Kea Observatories Near-Infrared(MKO-NIR) filter set, for 46 and 31 standard stars, respectively. The L'standards include 25 from the in-house `UKIRT Bright Standards' withmagnitudes deriving from Elias et al. and observations at the InfraredTelescope Facility in the early 1980s, and 21 fainter stars. The M'magnitudes derive from the results of Sinton and Tittemore. We estimatethe average external error to be 0.015 mag for the bright L' standardsand 0.025 mag for the fainter L' standards, and 0.026 mag for the M'standards. The new results provide a network of homogeneously observedstandards, and establish reference stars for the MKO system, in thesebands. They also extend the available standards to magnitudes whichshould be faint enough to be accessible for observations with moderndetectors on large and very large telescopes.
| Photoelectric Minima of Some Eclipsing Binary Stars
We present 29 minima observations of 11 eclipsing binaries.
| High-Precision Near-Infrared Photometry of a Large Sample of Bright Stars Visible from the Northern Hemisphere
We present the results of 8 yr of infrared photometric monitoring of alarge sample of stars visible from Teide Observatory (Tenerife, CanaryIslands). The final archive is made up of 10,949 photometric measuresthrough a standard InSb single-channel photometer system, principally inJHK, although some stars have measures in L'. The core of this list ofstars is the standard-star list developed for the Carlos SánchezTelescope. A total of 298 stars have been observed on at least twooccasions on a system carefully linked to the zero point defined byVega. We present high-precision photometry for these stars. The medianuncertainty in magnitude for stars with a minimum of four observationsand thus reliable statistics ranges from 0.0038 mag in J to 0.0033 magin K. Many of these stars are faint enough to be observable with arraydetectors (42 are K>8) and thus to permit a linkage of the bright andfaint infrared photometric systems. We also present photometry of anadditional 25 stars for which the original measures are no longeravailable, plus photometry in L' and/or M of 36 stars from the mainlist. We calculate the mean infrared colors of main-sequence stars fromA0 V to K5 V and show that the locus of the H-K color is linearlycorrelated with J-H. The rms dispersion in the correlation between J-Hand H-K is 0.0073 mag. We use the relationship to interpolate colors forall subclasses from A0 V to K5 V. We find that K and M main-sequence andgiant stars can be separated on the color-color diagram withhigh-precision near-infrared photometry and thus that photometry canallow us to identify potential mistakes in luminosity classclassification.
| Molecular Hydrogen in the Ring Nebula: Clumpy Photodissociation Regions
We present a 0.65" resolution H2 1-0 S(1) 2.122 μm imageof the Ring Nebula (NGC 6720), which was taken with the Near InfraredImager at the WIYN 3.5 m telescope on Kitt Peak. The high resolution ofthe H2 observation is sufficient to reveal the finerstructure of the molecular material in this nebula. The morphology ofthe molecular emission is compared to that of the ionized emission fromthe Ring Nebula as seen by the Hubble Space Telescope (HST; He II, [OIII], and [N II]), and it is clear that the dark clumps seen by HSTmatch the locations of clumpy H2 emission, suggesting thatthese clumps are similar to the cometary knots seen in the Helix Nebula.As with the Helix, the clumpy H2 emission from the main ringof the Ring Nebula is contained within the optically bright ionizednebula, implying that the molecular gas is shielded inside densecondensations. Comparison of the observed H2 average surfacebrightnesses for the Ring Nebula [(1.5+/-0.5)×10-4 ergscm-2 s-1 sr-1] with time-dependentmodels of the expected H2 emission from planetary nebulae(PNe) shows that it is consistent with H2 excitation inphotodissociation regions (PDRs), confirming previous suggestions.Comparison of the Ring Nebula H2 emission with a younger PN,NGC 2346, and an older PN, the Helix Nebula, suggests an evolution inH2 surface brightness consistent with the time-dependent PDRmodels. Moreover, the knots of molecular gas appear to become moreisolated as the PN evolves, consistent with optical studies of knots inPNe.
| The Visual Orbit and Evolutionary State of 12 Bootis
We report on the determination of the visual orbit of the double-linedspectroscopic binary system 12 Bootis with data obtained by the PalomarTestbed Interferometer in 1998 and 1999. 12 Boo is a nearly equal-massdouble-lined binary system whose spectroscopic orbit is well known. Wehave estimated the visual orbit of 12 Boo from our interferometricvisibility data fitted both separately and in conjunction with archivaland CORAVEL radial velocity data. Our 12 Boo orbit is in good agreementwith the spectroscopic results, and the physical parameters implied by acombined fit to our visibility data and radial velocity data result inprecise component masses. In particular, the orbital parallax of thesystem is determined to be 27.09+/-0.41 mas, and masses of the twocomponents are determined to be 1.435+/-0.023 Msolar and1.409+/-0.020 Msolar, respectively. Somewhat remarkably, eventhough the two components are nearly equal mass, the system exhibits asignificant brightness difference between the components in thenear-infrared and visible. We attribute this brightness difference toevolutionary differences between the two components in their transitionbetween main-sequence and giant evolutionary phases, and based ontheoretical isochrones we can estimate a system age. Further, becausethe atmospheres of the two components are becoming more convective, wesuggest the system components are currently at or near synchronousrotation, and the system orbit is in the process of circularizing.
| Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
| Towards a fundamental calibration of stellar parameters of A, F, G, K dwarfs and giants
I report on the implementation of the empirical surface brightnesstechnique using the near-infrared Johnson broadband { (V-K)} colour assuitable sampling observable aimed at providing accurate effectivetemperatures of 537 dwarfs and giants of A-F-G-K spectral-type selectedfor a flux calibration of the Infrared Space Observatory (ISO). Thesurface brightness-colour correlation is carefully calibrated using aset of high-precision angular diameters measured by moderninterferometry techniques. The stellar sizes predicted by thiscorrelation are then combined with the bolometric flux measurementsavailable for a subset of 327 ISO standard stars in order to determineone-dimensional { (T, V-K)} temperature scales of dwarfs and giants. Theresulting very tight relationships show an intrinsic scatter induced byobservational photometry and bolometric flux measurements well below thetarget accuracy of +/- 1 % required for temperature determinations ofthe ISO standards. Major improvements related to the actual directcalibration are the high-precision broadband { K} magnitudes obtainedfor this purpose and the use of Hipparcos parallaxes for dereddeningphotometric data. The temperature scale of F-G-K dwarfs shows thesmallest random errors closely consistent with those affecting theobservational photometry alone, indicating a negligible contributionfrom the component due to the bolometric flux measurements despite thewide range in metallicity for these stars. A more detailed analysisusing a subset of selected dwarfs with large metallicity gradientsstrongly supports the actual bolometric fluxes as being practicallyunaffected by the metallicity of field stars, in contrast with recentresults claiming somewhat significant effects. The temperature scale ofF-G-K giants is affected by random errors much larger than those ofdwarfs, indicating that most of the relevant component of the scattercomes from the bolometric flux measurements. Since the giants have smallmetallicities, only gravity effects become likely responsible for theincreased level of scatter. The empirical stellar temperatures withsmall model-dependent corrections are compared with the semiempiricaldata by the Infrared Flux Method (IRFM) using the large sample of 327comparison stars. One major achievement is that all empirical andsemiempirical temperature estimates of F-G-K giants and dwarfs are foundto be closely consistent between each other to within +/- 1 %. However,there is also evidence for somewhat significant differential effects.These include an average systematic shift of (2.33 +/- 0.13) % affectingthe A-type stars, the semiempirical estimates being too low by thisamount, and an additional component of scatter as significant as +/- 1 %affecting all the comparison stars. The systematic effect confirms theresults from other investigations and indicates that previousdiscrepancies in applying the IRFM to A-type stars are not yet removedby using new LTE line-blanketed model atmospheres along with the updatedabsolute flux calibration, whereas the additional random component isfound to disappear in a broadband version of the IRFM using an infraredreference flux derived from wide rather than narrow band photometricdata. Table 1 and 2 are only available in the electronic form of thispaper
| The near-infrared extinction law and limits on the pre-main-sequence population of the Rho Ophiuchi dark cloud
We describe new techniques to measure the NIR extinction law and toplace limits on the premain-sequence stellar population of a dark cloud.We analyze JHK imaging data for the central 1 sq deg of the Rho Ophiuchicloud core and show that nearly all stars projected onto regions of lowCS intensity, ICS 10 K km/s, are background stars. Most sources atlarger CS intensities lie within cloud material. We use the backgroundstars to derive the slope of the NIR extinction law, E(J-H)/E(H-K) =1.57 +/- 0.03. This result is consistent with previous extinction lawsbut has a factor of two to three smaller uncertainty. The new Rho Ophextinction law yields strong constraints on the number of previouslyundiscovered premain-sequence stars in the cloud, 46 +/- 11, and thenumber of previously undiscovered young stars with near-IR excesses, 15+/- 4. Neither limit exceeds the number of known premain-sequence starsin the cloud about 100. Thus, current samples of premain-sequence starsare reasonably complete for K = 14 or less.
| Near infrared surface photometry of late-type Virgo cluster galaxies
Near Infrared (K' band) surface photometry has been obtained for 102 (88late-type) Virgo cluster galaxies. A subset of 20 galaxies was alsoimaged in the H band. Magnitudes and diameters within the 21.5 and 22.0mag arcsec$^{-2}$ isophote, concentration indices and total H and K'magnitudes are derived. Basic statistical properties of a completesample of spiral galaxies spanning the range 6.3 < K'_T < 13.5 aregiven. Tables 3, 5 and 6 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html} Based on observations taken atthe Calar Alto Observatory, operated by the Max-Planck-Institut furAstronomie (Heidelberg) jointly with the Spanish National Commission forAstronomy.
| 1.65μm (H-band) surface photometry of galaxies. II. Observations of 297 galaxies with the TIRGO 1.5m telescope.
We present near-infrared H-band (1.65μm) surface photometry of 297galaxies (mostly) in the Coma Supercluster obtained with the ArcetriNICMOS3 camera, ARNICA, mounted on the Gornergrat Infrared Telescope.Magnitudes and diameters within the 21.5mag/arcsec^2^ isophote,concentration indices, and total H magnitudes are derived. Combiningthese observations with those obtained similarly using the Calar Altotelescopes (Paper I, 1996A&AS..120..489G) we find a strong positivecorrelation between the near-infrared concentration index and the galaxyH-band luminosity, and we analyze the consequent dependence ofnear-infrared growth-curves on H-band luminosity.
| 1.65 μm (H-band) surface photometry of disk galaxies. I. Observations of 158 galaxies with the Calar Alto 2.2 M telescope.
Near Infrared (H-band) surface photometry of 158 (mostly) disk galaxiesbelonging to the Coma Supercluster and to the A262 and Cancer clusterswas obtained using the 256^2^ NICMOS3 array MAGIC attached to the 2.2mCalar Alto telescope. Magnitudes and diameters within the21.5mag/arcsec^2^ isophote, concentration indices and total H magnitudesare derived.
| Near-Infrared Surface-Photometry of Edge-on Scd Galaxies, NGC 3556 and NGC 4244
Near-infrared images in the J and K' bands of two edge-on late-typegalaxies, NGC 3556 and NGC 4244, were obtained with the newly developedcommon-use instrument for infrared imaging and spectroscopy at theOkayama Astrophysical Observatory (OASIS). These images were analyzed toyield the surface-photometric and model parameters for the globalstructure of these Scd galaxies. NGC 3556 shows a disk and a bar-likestructure, both of which have an approximately exponentialsurface-brightness distribution. The absorption feature of NGC 3556 iscomplex, and only the most prominent central dark lane of A_J<0.5 wastaken into the modeling. NGC 4244 comprises a disk and a weak bulge,both having an approximately exponential surface-brightnessdistribution, suffering under negligible internal absorption by a faintdark lane of A_J<0.1. Global models of the 3-D emissivity structureand absorption layer have been constructed to reproduce the observedmain features. The global models indicate that both galaxies areoptically thin in the V band when seen face on (tau_ {0,V} < 0.4),with the reservation of a possible presence of locally opaque structuresin NGC 3556. Brief discussions are given concerning the insufficiency ofsimple absorption-layer models and the strong contrast between the twoScd galaxies regarding their interstellar matter and star-formingactivities.
| Starburst Galaxies. II. Imaging and Spectroscopy of a Radio-selected Sample
We present J-, H-, and K-band images and low-resolution K-band spectraof the 20 most luminous starburst galaxies from the survey of Condon,Frayer, & Broderick. Optical rotation curves are also shown for 10of these galaxies. Near-infrared colors, optical depths, CO indices, anddynamical masses are calculated. The near-infrared colors of thestarburst nuclei are significantly redder than those observed in"normal" galaxies. Together, the Brγ and radio fluxes availablefor five of the galaxies imply that the starbursts are heavily obscured;an average extinction of A_V_~ 25 is derived. Strong CO absorptionfeatures indicate that late-type evolved stars are present in many ofthe starbursts. The average dynamical mass of the starburst region isfound to be (1.0 +/- 0.4) x 10^9^ M_sun_.
| Determination of effective temperatures for an extended sample of dwarfs and subdwarfs (F0-K5).
We have applied the InfraRed Flux Method (IRFM) to a sample of 475dwarfs and subdwarfs in order to derive their effective temperatureswith a mean accuracy of about 1.5%. We have used the new homogeneousgrid of theoretical model atmosphere flux distributions developed byKurucz (1991, 1993) for the application of the IRFM. The atmosphericparameters of the stars cover, roughly, the ranges:3500K<=T_eff_<=8000K -3.5<=[Fe/H]<=+0.53.5<=log(g)<=5. The monocromatic infrared fluxes at the continuum,and the bolometric fluxes are derived using recent results, whichsatisfy the accuracy requeriments of the work. Photometric calibrationshave been revised and applied to estimate metallicities, although directspectroscopic determinations were preferred when available. The adoptedinfrared absolute flux calibration, based on direct optical measurementsof angular stellar diameters, sets the effective temperatures determinedusing the IRFM on the same scale than those obtained by direct methods.We derive three temperatures, T_J_, T_H_ and T_K_, for each star usingthe monochromatic fluxes at different infrared wavelengths in thephotometric bands J, H, and K. They show good consistency over 4000 K,and no trend with wavelength may be appreciated. We provide a detaileddescription of the steps followed for the application of the IRFM, aswell as the sources of the errors associated to the different inputs ofthe method, and their transmission into the final temperatures. We alsoprovide comparison with previous works.
| The Nuclear Energy Sources Powering Bright Infrared-selected Galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...447..545A&db_key=AST
| Nuclear bars and blue nuclei within barred spiral galaxies
Multicolour near-IR photometry for a sample of 32 large barred spiralgalaxies is presented. By applying ellipse-fitting techniques, weidentify significant isophote twists with respect to the primary baraxis in the nuclear regions of ~70 per cent of the sample. These twistsare identified in galaxies as late as SBbc, and are clearlydistinguishable from spiral-arm structure. At most, seven of thegalaxies with isophote twists are inferred to possess secondary(nuclear) bars, the axial ratios of which appear to correlate withmorphological type. The remainder may result from triaxial bulges, orfrom oblate bulges misaligned with the primary bar. The near-IR colourdistributions in these data show evidence for (red) circumnuclearstar-forming rings in four galaxies. The majority of the sample (19)also possess striking blue nuclear regions, bluer than typical oldstellar populations by ~0.3 mag in (J-H) and ~0.23 mag in (H-K). Suchblue colours do not appear to correlate with the presence of nuclearrings or pseudo-rings, nor with the activity of the host galaxy (asdetermined from emission-line spectroscopic characteristics). Severalmechanisms to explain this blue colour are considered.
| Near Infrared Imaging of Dwarf Ellipticals Irregulars and Blue Compact Galaxies in the Virgo Cluster
New near-IR images are presented for 13 dwarf galaxies in the Virgocluster. Together with previous data these provide a data base of JHKimaging for 26 dwarf ellipticals (dEs), dwarf irregulars (dIs) and bluecompact dwarfs (BCDs). These images show the dIs to be highly asymmetricand unrelaxed, implying that they are dynamically young and unevolved.This is consistent with their blue near-IR and optical-IR colours whichare most easily explained by young stellar populations. The dEs aresymmetrical and apparently relaxed, with very uniform colours indicatingthat they are dominated by old stars. They generally have exponentiallight profiles, but the brighter galaxies tend to exhibit more cuspedlight distributions, similar to the de Vaucouleurs profiles of brightellipticals. The BCDs have moderately asymmetric light profiles, andparadoxically red colours, possibly indicating an intermediate-agestellar population. They are probably dEs which have undergone bursts ofstar formation in the last few X 10^9^ years, whilst the dIs are afundamentally distinct population. Colour gradients are present in manyof the galaxies, invariably in the sense that the nuclei are redder thanthe surrounding galaxy light.
| Multifrequency windows on spiral galaxies. 3.Internal extinction at optical and near-infrared wavelengths
We present aperture photometry data in the H, V, Band U bands of about100 spiral galaxies belonging to 8 nearby clusters and to the ComaSupercluster. The data are used in conjunction with other measurementsavailable in the literature to study, for the first time on the same setof approximately 500 galaxies, the internal extinction in spiral disksin the H, V, B and U bands. We study the color(V-H, B-H, U-H)inclination relation to determine the color-extinction coefficients. Wederive the lower limits to the internal extinction coefficients atoptical wavelengths assuming that galaxies are fully transparent in theH band. In the opposite assumption that galaxies are optically thick inthe blue we use the surface brightness--inclination relation to derivethe upper limits to the above parameters. Assuming a sandwich model forthe distribution of stars and of the absorbing dust, we find that bothsets of parameters are consistent with tau greater than 1 in theoptical. The ratio of the dust to star z-scales decreases withincreasing wavelength, indicating that the thickness of the distributionof the young stars is narrower than that of the old stars. We also findthat the face-on extinction correction is not negligible.
| The faintest stars - Infrared photometry, spectra, and bolometric magnitude
Infrared JHKLL-prime photometry, and low resolution IF spectra arepresented for the faintest stars. The stellar H2O bands which dominatethe atmospheres of these stars were studied. L band fluxes of thesestars are considerably depressed relative to L prime fluxes by thepresence of stellar H2O absorption. Strong H2O absorption is observed inthese infrared spectra. The amount of flux which is 'overcounted' whenH2O absorption bands are ignored is examined. Bolometric fluxes arecalculated using broadband photometry alone, requiring a correction ofonly approximately 5 percent to 10 percent. Photometric and spectraldata is used to evaluate bolometric corrections and magnitudes of asample of late type M dwarfs.
| Near-infrared, polarimetric imaging of the bipolar lobes of GSS 30 - Protostellar infall and/or outflow?
The morphology noted in the present 1.65 and 2.2 micron polarimetricimages of the bipolar reflection nebula GSS 30 is consistent with thatexpected for protostellar infall and/or outflow, and the polarizationmaps suggest that the scattering orbital depth is larger along the limbsand the neck of the nebula than along the polar axis. Interpreting thelobes as cavities formed by polar outflows leads to the suggestion thatthe outflow is characterized by temporal variability in either mass-lossrate or outflow velocity, on time scales of less than several hundredyears.
| Near-infrared calibration stars for the Teide Observatory
Not Available
| The accuracy of infrared photometry with arrays
The photometric accuracy and repeatability of an InSb array in theinfrared camera IRCAM is investigated. Measurements of standard starsare described; these were made using the United Kingdom Infrared 3.8-mTelescope (UKIRT) over five nights in May 1988, as part of anobservational program on globular clusters. Observations were made atwavelengths of 1.25 (J) and 2.2 microns (K). The results show clearlythat the camera-array combination is capable of a photometric accuracyof better than 1 percent when the standard-star images obtained withshort on-chip exposure (0.5 sec) are flat fielded with long on-chipexposure (7-50 sec) sky flats. Linearity corrections determined in thelaboratory were applied to the data and there was no evidence ofresidual nonlinearity of greater than 2 percent over the magnitude range6.5-13.0 m. The range of mean nightly zero points at K during the fivenights was 0.03 m, showing that both the site and the camera system werevery stable over this period. At J the zero points were less welldetermined and had twice this range during three nights.
| Infrared mapping of M82 - A starburst in an edge-on barred galaxy
New 1-30-micron images of the starburst galaxy M82 are presented. Theappearance of M82 at 2 microns indicates that a bar about 1 kpc long islocated at its center. This bar may dramatically influence the gasdynamics and may have caused the formation of the central gas and dusttoroid associated with the luminous episode of star formation. Themid-IR maps define the structure of the toroid out to 30 microns andshow that the extent of the emitting region is at least 1.3 kpc. Theabsorption optical depth determined from 1-2 micron colors correspondsto A(v) less than about 8 and is distributed in a ridge spanning thestarburst region and closely resembling the distribution of H I opticaldepth. Finally, the contribution that very small grains may make to the10-micron emission is considered, and it is concluded, by comparison toGalactic H II regions, that their mid-IR emission is significant.
| Globular cluster distances from the RR Lyrae log(period)-infrared magnitude relation
The present determinations of log(period)-2.2 micron IR relationship forRR Lyr stars in eight clusters indicate no sign of scatter in therelation apart from observational error. It is suggested that veryaccurate relative distances, insensitive to both reddening errors andthe effects of metallicity, are obtainable, although mass differencesbetween variables in different clusters may still introduce relativedistance uncertainties. A comparison of the absolute calibration of Kmagnitudes of two field stars obtained with an IR-flux method form ofthe Baade-Wesselink analysis to three other sets of distancemeasurements shows good agreement with those of Richer and Fahlman(1987).
| Velocity-resolved images of molecular hydrogen in the colliding galaxy NGC 6240 - Evidence of a global shock
Images of the nuclear region of NGC 6240 taken in the 2.122 micron, v =1-0 S(1) quadrupole line of molecular hydrogen demonstrate that the lineemission is extended and distinct from the two nuclei producing most ofthe continuum emission. A region about 2 arcsec southwest of thesouthern nucleus produces almost 20 percent of the total line radiation,yet has no detectable 2 micron continuum. The H2 lines are asymmetric,with very little emission on the short-wavelength side of the linepeaks. These results indicate that a global phenomenon, such as thedissipative collision of two disks of molecular material, is takingplace.
| Near-infrared observations of galaxies in the Coma supercluster
Near-IR magnitudes have been obtained for 136 galaxies in the Coma/A1367supercluster region, and near-IR colors (J-H) and (H-K) for 90 and 87objects, respectively. The near-IR colors are contained in a small rangeand do not depend on morphological types, galaxy inclination, orenvironment. Optical-to-IR colors depend strongly on a galaxy'smorphological type and inclination. There is a dependence of therelative excess of radio, and to a lesser degree, of far-IR emission onrecent star formation activity. The magnitude-line width relation forgalaxies in Coma and A1367 obtained with these data has a larger spreadthan previously found with smaller samples. The data suggest a distancemodulus to Coma of about 35, regardless of the choice of primarycalibrators.
| An atlas of stellar spectra between 2.00 and 2.45 microns
Spectra between 2.00 and 2.45 microns, with a resolution of about 0.02micron are presented for a sample of 73 stars. These stars include asupergiant, giants, dwarfs and subdwarfs, and have a range in chemicalabundance from about -2 to +0.5 dex.
| The cool components of symbiotic stars. II - Infrared photometry
This paper reports IR photometry for a sample of symbiotic binaries andK-M comparison stars. Measured CO absorption-band strengths of the coolcomponents in symbiotic stars generally are comparable to those ofsingle red giant and bright giant stars, but it is difficult todetermine the luminosity classes of these objects from their photometricCO indices. The 12-micron excesses observed in symbiotics require theircool components to lose mass more rapidly than do single red giantstars. Thus, mass-loss rates derived for red giants in close binarysystems may not be accurate estimates for mass loss in single redgiants.
| The IR morphology of the proto-planetary nebula M2-9
The first high spatial resolution IR images of the protoplanetary nebulaM2-9 are presented. Observations, made with the new UKIRT 2D infraredarray camera, IRCAM, at J, H, and K, show the changing morphology ofM2-9 with deeper looks into the infrared. At the shorter infraredwavelengths the knots, visible in earlier optical CCD observations, areseen predominantly on the east side of the nebula. Photometry at K showsthe nebula to a limiting magnitude of about 18th/square arcsecond, whereit is considerably more uniform in appearance than at shorterwavelengths. J and H photometry calibrated using earlier aperturemeasurements have allowed the formation of (J-K) and (H-K) color images.These show a predominant disk-like structure 20 arcsec in sizestretching across the core region of M2-9. The reddening in the diskpeaks at over 6 mag in (J-K) in two locations symmetrically placed eastand west of the intensity peak.
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| Сазвежђа: | Волар |
| Ректацензија: | 14h42m39.56s |
| Deклинација: | +36°45'24.3" |
| Apparent магнитуда: | 7.278 |
| Даљина: | 118.343 parsecs |
| Proper motion RA: | 29 |
| Proper motion Dec: | -8.5 |
| B-T magnitude: | 7.482 |
| V-T magnitude: | 7.295 |
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