Contents
Images
Upload your image
DSS Images Other Images
Related articles
Optical and infrared observations of the TypeIIP SN2002hh from days 3 to 397
We present optical and infrared (IR) observations of the TypeII SN2002hhfrom 3 to 397d after explosion. The optical spectroscopic (4-397d) andphotometric (3-278d) data are complemented by spectroscopic (137-381d)and photometric (137-314d) data acquired at IR wavelengths. This is thefirst time L-band spectra have ever been successfully obtained for asupernova (SN) at a distance beyond the Local Group. The VRI lightcurves in the first 40d reveal SN2002hh to be an SNIIP (plateau) - themost common of all core-collapse SNe. SN2002hh is one of the most highlyextinguished SNe ever investigated. To provide a match between itsearly-time spectrum and a coeval spectrum of the TypeIIP SN1999em, aswell as maintaining consistency with KI interstellar absorption, weinvoke a two-component extinction model. One component is due to thecombined effect of the interstellar medium (ISM) of our Milky Way Galaxyand the SN host galaxy, while the other component is due to a `dustpocket' where the grains have a mean size smaller than in the ISM. Theearly-time optical light curves of SNe1999em and 2002hh are generallywell matched, as are the radioactive tails of these two SNe and SN1987A.The late-time similarity of the SN2002hh optical light curves to thoseof SN1987A, together with measurements of the optical/IR luminosity and[FeII]1.257μm emission indicate that 0.07 +/- 0.02Msolarof 56Ni was ejected by SN2002hh. However, during the nebularphase the HKL' luminosities of SN2002hh exhibit a growing excess withrespect to those of SN1987A. We attribute much of this excess to anIR-echo from a pre-existing, dusty circumstellar medium. Based on anIR-echo interpretation of the near-IR (NIR) excess, we deduce that theprogenitor of SN2002hh underwent recent mass-loss of~0.3Msolar. A detailed comparison of the late-time opticaland NIR spectra of SNe1987A and 2002hh is presented. While the overallimpression is one of similarity between the spectra of the two events,there are notable differences. The MgI1.503μm luminosity of SN2002hhis a factor of 2.5 greater than in SN1987A at similar epochs, yet coevalsilicon and calcium lines in SN2002hh are fainter. Interpreting thesedifferences as being due to abundance variations, the overall abundancetrend between SN1987A and 2002hh is not consistent with explosion modelpredictions. It appears that during the burning to intermediate-masselements, the nucleosynthesis did not progress as far as might have beenexpected given the mass of iron ejected. Evidence for mixing in theejecta is presented. Pronounced blueshifts seen in the more isolatedlines are attributed to asymmetry in the ejecta. However, during thetime-span of these observations (~1-yr post-explosion) we find noevidence of dust condensation in the ejecta such as might have beenrevealed by an increasing blueshift and/or attenuation of the red wingsof the emission lines. Nevertheless, the clear detection of firstovertone CO emission by 200d and the reddening trend in (K -L')0 suggest that dust formation in the ejecta may occur atlater epochs. From the [OI] λλ6300, 6364Å doubletluminosity we infer a 16-18Msolar main-sequence progenitorstar. The progenitor of SN2002hh was probably a red supergiant with asubstantial, dusty wind.
| Calibration of the Infrared Telescope Facility National Science Foundation Camera Jupiter Galileo Data Set
The NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, setaside some time on about 500 nights from 1995 to 2002, when the NSFCAMfacility infrared camera was mounted and Jupiter was visible, for astandardized set of observations of Jupiter in support of the Galileomission. The program included observations of Jupiter, nearby referencestars, and dome flats in five filters: narrowband filters centered at1.58, 2.28, and 3.53 μm, and broader L' and M' bands that probe theatmosphere from the stratosphere to below the main cloud layer. Thereference stars were not cross-calibrated against standards. Weperformed follow-up observations to calibrate these stars and Jupiter in2003 and 2004. We present a summary of the calibration of the Galileosupport monitoring program data set. We present calibrated magnitudes ofthe six most frequently observed stars, calibrated reflectivities, andbrightness temperatures of Jupiter from 1995 to 2004, and a simplemethod of normalizing the Jovian brightness to the 2004 results. Ourstudy indicates that the NSFCAM's zero-point magnitudes were not stablefrom 1995 to early 1997, and that the best Jovian calibration possiblewith this data set is limited to about +/-10%. The raw images andcalibration data have been deposited in the Planetary Data System.
| 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.
| The Compact H II Region S88B: Excitation and Extinction
We have undertaken an investigation into the excitation of, and dustextinction to, the massive star formation region S88B. Studying stellarproperties of the wide-field Two Micron All Sky Survey (2MASS) J (1.23μm), H (1.65 μm), and Ks (2.16 μm) images, we havedetermined the extent of, and extinction to, the molecular cloudassociated with the ultracompact H II regions S88B-1 and S88B-2 and witha newly described infrared H II region. Infrared observations ofBrγ and Brα hydrogen recombination lines provide extinctionmaps to the infrared H II region, and 3.3 and 3.4 μm images show thepolycyclic aromatic hydrocarbon (PAH) emission distribution. We alsoreport the detection of an infrared counterpart to S88B-2.
| Imaging and Spatially Resolved Spectroscopy of AFGL 2688 in the Thermal Infrared Region
We present ground-based high-resolution (~0.3") imaging of AFGL 2688 atL' (3.8 μm) and M' (4.7 μm). A wealth of structure in the centralregion is revealed as a consequence of less extinction in the thermalinfrared. A clear border in the southern lobe at L' corresponds to theedge of the heavily obscured region in visible, indicating that there isa dense material surrounding the central region. The images also show anarrow dark lane oriented to 140° east of north with the normal at50°. The normal position angle is inconsistent with the opticalpolar axis (P.A.=15deg) but is aligned to the high-velocityCO components found in the radio wavelength observations. The centralstar remains invisible at L' and M'. Several clumpy regions in the northlobe dominate in L' and M' luminosity. In particular, a pointlike source(peak A) at 0.5" northeast of the center of the nebula exhibits thehighest surface brightness with a very red spectral energy distribution(SED). Based on the almost identical SED at adjacent regions, we suggestthat the pointlike source is not self-luminous, as was proposed, but isa dense dusty blob reflecting thermal emission from the central star. Wealso present spatially resolved slit spectroscopy of the bright dustyblobs. An emission feature at 3.4 μm as well as at 3.3 μm isdetected everywhere within our field of view. There is no spatialvariation in the infrared emission feature throughout the observed area(0.2"-1.5", or 240-1800 AU from the central source). The constant fluxratio of the emission feature relative to the continuum is consistentwith the view that the blobs are mostly reflecting the light from thecentral star in the 3 μm region. Based on data collected at SubaruTelescope, which is operated by the National Astronomical Observatory ofJapan.
| H II Emission from a Complete Spectroscopic Survey of Be Stars in h and χ Persei
We describe data for emission-line B stars observed in a spectroscopicsurvey of h and χ Persei. The survey is complete to V=12.5 andcovers an area of ~1100 arcmin2 roughly centered on the twoclusters. We detect 32 Be stars; some have low Hα emissionstrength. Seven of these are new identifications; seven others areconfirmations of Be stars previously identified using photometry. Fiveof the observed Be stars show significant Hα profile variationsfrom epoch to epoch. We show that spectral indices yield physicalcharacteristics of the H II emission region. This automatic method isrobust and easily applied to large spectroscopic samples. We inferHα:Hβ flux ratios of 2-5 and observe a linear relationshipbetween Hα emission and J-K color for these stars. We include aHertzsprung-Russell diagram for the B-type stars in the clusters.
| Quiescent Giant Molecular Cloud Cores in the Galactic Center
We have used the Long Wavelength Spectrometer aboard the Infrared SpaceObservatory to map the far-infrared continuum emission (45-175 μm)toward several massive giant molecular cloud (GMC) cores located nearthe Galactic center. The observed far-infrared and submillimeterspectral energy distributions imply low temperatures (~15-22 K) for thebulk of the dust in all the sources, which is consistent with externalheating by the diffuse interstellar radiation field (ISRF) and suggeststhat these GMCs do not harbor high-mass star formation sites, despitetheir large molecular mass. Observations of far-infrared atomicfine-structure lines of C II and O I indicate an ISRF enhancement of~103 in the region. Through continuum radiative transfermodeling, we show that this radiation field strength is in agreementwith the observed far-infrared and submillimeter spectral energydistributions, assuming primarily external heating of the dust with onlylimited internal luminosity (~2×105 Lsolar).Spectroscopic observations of millimeter-wave transitions ofH2CO, CS, and C34S carried out with the CaltechSubmillimeter Observatory and the Institut de Radio AstronomieMillimétrique (IRAM) 30 m telescope indicate a gas temperature of~80 K, which is significantly higher than the dust temperature, and adensity of ~1×105 cm-3 in GCM 0.25+0.01, thebrightest submillimeter source in the region. We suggest that shockscaused by cloud collisions in the turbulent interstellar medium in theGalactic center region are responsible for heating the molecular gas.This conclusion is supported by the presence of widespread emission frommolecules such as SiO, SO, and CH3OH, which are consideredgood shock tracers. We also suggest that the GMCs studied here arerepresentative of the ``typical,'' pre-star-forming cloud population inthe Galactic center.
| 2 Micron Narrowband Adaptive Optics Imaging in the Arches Cluster
Canada-France-Hawaii-Telescope adaptive optics bonnette images throughnarrowband filters in the K band are presented for the Arches cluster.Continuum fluxes, line fluxes, and equivalent widths are derived fromhigh angular resolution images, some nearly diffraction limited, for thewell-known massive stars in the Arches cluster. Images were obtained inthe lines He I 2.06 μm, H I Brγ (2.17 μm), and He II 2.19μm, as well as continuum positions at 2.03, 2.14, and 2.26 μm. Inaddition, fluxes are presented for H I Pα (1.87 μm) and anearby continuum position (1.90 μm) from Hubble Space Telescopearchival data.2 The 2 μm and Pαdata reveal two new emission-line stars and three fainter candidateemission-line objects. Indications for a spectral change of one objectbetween earlier observations in 1992-1993 and our data from 1999 arefound. The ratio of He II 2.19 μm to Brγ emission exhibits anarrow distribution among the stars, suggesting a narrow evolutionaryspread centered predominantly on spectral types O4 If or Wolf-Rayetstars of the WN7 subtype. From the approximate spectral types of theidentified emission-line stars and comparisons with evolutionary modelswe infer a cluster age between ~2 and 4.5 Myr.
| Near-infrared line imaging of the circumnuclear starburst rings in the active galaxies NGC 1097 and NGC 6574
We present high spatial resolution near-infrared broad-band JHK andBrgaussmma 2.166 mum and H_2 1-0 S(1) 2.121 mum emission line images ofthe circumnuclear star formation rings in the LINER/Seyfert 1 galaxy NGC1097 and in the Seyfert 2 galaxy NGC 6574. We investigate themorphology, extinction, and the star formation properties and history ofthe rings, by comparing the observed properties with an evolutionarypopulation synthesis model. The clumpy morphology in both galaxiesvaries strongly with wavelength, due to a combination of extinction,emission from hot dust and red supergiants, and the age of the stellarpopulations in the rings. The near-infrared and radio morphologies arein general agreement, although there are differences in the detailedmorphology. From the comparison of Brgaussmma and Hα fluxes, wederive average extinctions toward the hot spots A_V = 1.3 for NGC 1097and A_V = 2.1 for NGC 6574. The observed H_2/Brgaussmma ratios indicatethat in both rings the main excitation mechanism of the molecular gas isUV radiation from hot young stars, while shocks can contribute only in afew regions. The starburst rings in both galaxies exhibit smallBrgaussmma equivalent widths. Assuming a constant star formation ratewith M_u = 100 M_sun results in extremely long ages (up to 1 Gyr), indisagreement with the morphology and the radio spectral index of thegalaxies. This situation is only slightly remedied by a reduced uppermass cutoff (M_u = 30 M_sun). We prefer a model of an instantaneousburst of star formation with M_u = 100 M_sun occurring sim6-7 Myr ago.Gaseous nuclear bars parallel to the stellar nuclear bar were detectedin both galaxies, and we derive M sim100 M_sun for the mass of theexcited nuclear H_2 emission. Finally, we briefly discuss the connectionbetween the rings, bars and the fuelling of nuclear activity.
| Young red supergiants and the near-infrared light appearance of disk galaxies
We have searched for spatial variations in the 2.3 m photometric COindex within the disks of three nearby galaxies. This index measures thestrength of the absorption bands of molecular CO in stellar atmospheresand is strong in cool, low surface gravity stars, reaching the largestvalues for red supergiants. We observe significant spatial CO indexvariations in two galaxies, indicating that the dominant stellarpopulation in the NIR is not everywhere the same. Central CO index peaksare present in two galaxies; these could be due to either metallicitygradients or to recent star formation activity. In addition, significantazimuthal CO index variations are observed in one. Because strongazimuthal metallicity gradients are physically implausible in diskgalaxies, these features are most naturally explained by the presence ofa young stellar population. The fraction of 2 m light due to youngstellar populations in star-forming regions can be calculated from ourdata. Overall, young stellar populations can contribute 3 percent of theNIR flux of a (normal) galaxy, which is consistent with other globalproperties. Locally, this fraction may rise to 33 percent. Thus, youngstars do not dominate the total NIR flux, but can be locally dominant instar-forming regions, and can bias estimates of spiral arm amplitude orother nonaxisymmetric structures in galaxies' mass distributions.
| 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 imaging and spectroscopy of the IRAS 20126+4104 region
In this paper we present near-infrared images and K'-band spectra(1.95-2.30 microns ) of the nebulae located in the IRAS 20126+4104region. We find bright cometary shaped objects to the Northwest of theIRAS position and other emission line objects to the Southeast. We havedetected 6 low excitation emission lines of molecular hydrogen, andpresent spatially resolved excitation temperatures, 1-0 S(1)/2-1 S(1)line ratios and ortho-para ratios for the brighter emission line objectsnear the IRAS source. The integrated flux in the H2 1-0 S(1)line of the brighter object located to the Northwest of the IRASposition is 6.85 *E(-13) erg cm(-2) s(-1) , integrated within anaperture of 10.2 arcsec(2) . >From a spectrophotometric analysis, weconclude that the H2 emission observed in this nebula ismainly produced by collisional excitation combined with fluorescentH2 emission. However, it is unclear from our observationswhether the UV radiation field that would be responsible for thefluorescent component is produced by the IRAS source itself, or by thestars embedded at the Eastern edges of two of the observedcondensations. Based on observations obtained at the ObservatorioAstronomico Nacional at San Pedro Martir, B.C. Mexico
| The Tokyo PMC catalog 90-93: Catalog of positions of 6649 stars observed in 1990 through 1993 with Tokyo photoelectric meridian circle
The sixth annual catalog of the Tokyo Photoelectric Meridian Circle(PMC) is presented for 6649 stars which were observed at least two timesin January 1990 through March 1993. The mean positions of the starsobserved are given in the catalog at the corresponding mean epochs ofobservations of individual stars. The coordinates of the catalog arebased on the FK5 system, and referred to the equinox and equator ofJ2000.0. The mean local deviations of the observed positions from theFK5 catalog positions are constructed for the basic FK5 stars to comparewith those of the Tokyo PMC Catalog 89 and preliminary Hipparcos resultsof H30.
| Infrared Polarimetry of Star-Forming Regions: The Serpens Cloud Core
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....113.1057S&db_key=AST
| Multiwavelength Observations of Collisional Ring Galaxies.I.Broad-Band Images, Global Properties, and Radial Colors of the Sample Galaxies
This is one of a series of papers discussing the optical, infrared andradio continuum properties of a sample of collisional ring galaxies. Thepresent paper concentrates on the global broad-band optical (B, V and R)and near-IR (J, H and K) images of the galaxies and describe theirglobal properties. An analysis of the colors of the galaxies over avariety of wavelength baselines is described. In the B and V bands, thebluest colors are found in the outer bright ring. The B-V colors of thesample of galaxies are blue, the median value for the sample is B-V =0.60, and V-K= 2.33 mag. The IR morphology of the galaxies is, in mostcases, very similar to that of the B-band data, suggesting that theclumpy appearance of the star formation in the outer rings is real, andnot a result of patchy dust obscuration. Only in one ring (WN1, aSeyfert ring galaxy) was the IR morphology different from the optical,suggesting the presence of significant dust in the disk. In II Hz 4,faint spiral arms are seen within the ring. There is a suggestion thatthe larger rings have redder V-K colors, which may be due to anincreased incidence of nuclear bulges in larger ring galaxies. Radialprofiles of surface brightness and color are presented for fourgalaxies. In all cases, the colors becomes bluer as one proceedsradially outwards, but in two galaxies, the rings redden again outsidethe main ring, suggesting the existence of a red stellar population thatmay have pre-dated the collisions.
| Near-Infrared Spectra and the Evolutionary Status of Young Stellar Objects: Results of a 1.1-2.4 (??) Survey
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....112.2184G&db_key=AST
| Fainter Southern JHK Standards Suitable for Infrared Arrays
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995MNRAS.276..734C&db_key=AST
| An Infrared Spectroscopic Survey of the rho Ophiuchi Young Stellar Cluster: Masses and Ages from the H-R Diagram
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...450..233G&db_key=AST
| Multiwavelength observations of ring galaxies. 2: Global star formation in ring galaxies
We present optical H-alpha emission-line images and K band near-infraredimages of a sample of collisionally formed ring galaxies. These are usedto determine the distribution of star formation and the distribution ofthe old stellar population, respectively, in the galaxies. Our resultsshow ring galaxies to have similar Hcx luminosities to starburstgalaxies, with star formation being contained almost exclusively in thering. In the larger ring galaxies we observe the ionized hydrogen to lieon the outer edge of the underlying, broader, K band ring. No conclusiveevidence is found in our sample for a true underlying stellar densitywave. Rather, the evidence suggests that either the density waves havepassed into the outer, mainly H I disk of the galaxies or that theprogenitor galaxies were mainly gas-rich low surface brightness objectsand that most of the optical/IR light we now observe has resulted fromrecent star formation in the expanding ring.
| A K' imaging survey of molecular outflow sources
A K'-band imaging survey with a approximately equals 8 min x 3 min fieldof view of all regions associated with CO molecular outflow from thelist of Fukui (1989) has been conducted. We present the individualimages and describe individual nebulous objects and star clusters. Thedata, including photometric calibration data, are being published asFITS files on a CD-ROM. The vast majority of all outflow sources areassociated with nebulosity detectable in K', so such nebulae can be usedas tracers for very young stars. We find a significant fraction(one-third) of molecular outflow sources to be associated with clustersof young stars. Most of the young embedded clusters show peaks in theirK' magnitude histograms that, if interpreted as an evolutionary effect,indicate average ages of the embedded star population of is less than 1x 106 yr.
| The lowest mass stars in the Hyades
In Bryja et al. (1992), we presented proper motions and photometry of 12very low mass star and brown dwarf candidates in the Hyades cluster,selected on the basis of colors and proper motions measured from threeepochs of plate material. We here present new observations of some ofthese candidates, including seven low resolution spectra, plus motionsand photometry of 17 fainter additional candidates. Most of thecandidates have JHK colors typical of M5-M8 dwarfs, while their opticalcolors are consistent with earlier M spectral types. The availablespectra consist of late M dwarfs with H alpha emission featuresindicative of Hyades membership, earlier M dwarf background stars, andtwo anomalous objects with early M dwarf features but unusually redcontinua. We find that the proper motion distribution of faint red fieldstars in the region is irregular, and it is not possible to determine ifthe anomalous objects are Hyades members or background field stars. Inthe most conservative view, only five of our 29 candidates are Hyades.These five stars have optical and infrared colors consistent with thebottom of the Hyades main sequence, with four of them also shown to havelate M dwarf spectra. It follows that these are the lowest mass starsknown in the Hyades (M is about 0.1 solar mass).
| 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.
| The dust coma of Comet P/Giacobini-Zinner in the infrared
The paper presents 1-20-micron photometry of P/Giacobini-Zinner obtainedat the NASA Infrared Telescope Facility, during 1985 June-September (r =1.57-1.03 AU). A broad, weak 10-micron silicate emission feature wasdetected on August 26.6; a similar weak emission feature could have beenhidden in the broadband photometry on other dates. The total scatteringand emitting cross section of dust in the inner coma was similar to thatin other short-period comets, but a factor of 10 (r = 1.56 AU) to 100 (r= 1.03 AU) lower than the amount of dust in Comet Halley. The thermalemission continuum can be fit with models weighted toward either smallor large absorbing grains. The dust production rate near perihelion wasabout 100,000 g/s (small-grain model) to about 1,000,000 g/s(large-grain model). The corresponding dust/gas mass ratio on August 26was about 0.1-1. A silicate-rich heterogeneous grain model with anexcess of large particles is compatible with the observed spectrum ofGiacobini-Zinner on August 26. Thus, weak or absent silicate emissiondoes not necessarily imply an absence of silicates in the dust, althoughthe abundance of silicate particles not greater than 1 micron radiusmust have been lower than in Comet Halley.
| A filter for deep near-infrared imaging
The K passband (central wavelength 2.2 microns, FWHM 0.4 micron) is thelongest wavelength standard near-IR passband through which deepground-based imaging is possible. Thermal emission from telescope,instrument, and sky limits the depth to which such imaging can reach byproducing strongly temperature-dependent backgrounds in the range11-13.5 mag/sq arcsec. This paper describes how a passband, which isdenoted as K-prime, located slightly shortward of the standard Kpassband (central wavelength 2.1 microns), yet still within the sameatmospheric window, leads to a significantly lower thermal component ofthe background, reducing the background surface brightness by up to 0.9mag sq arcsec, and thereby allowing deeper imaging to be obtained in thesame integration time. The photometric differences between the K-primefilter and the standard K filter are discussed.
| Two protostar candidates in the bright-rimmed dark cloud LDN 1206
The discovery of several near IR objects associated with two IRAS pointsources in the LDN 1206 region is reported. IRAS 22272 + 6358A isprobably a 'protostar' which is seen only in scattered light at near-IRwavelengths because of heavy obscuration by an almost edge-oncircumstellar disk. In contrast, IRAS 22272 + 6358B is directly visibleat these wavelengths and is perhaps an object which lies betweenprotostars and T-Tauri stars in its evolution. Both direct andpolarimetric K-band images of the region are presented, as well asspectral energy distributions constructed from J, H, K, L, L-prime, andM data and published far-IR and mm data.
| JHKLM standard stars in the ESO system
A list of 199 standard stars suitable for the ESO standard photometricsystem at JHKLM is given. Faint stars (although brighter than K = 7.7)to be used on larger telescopes are included. This list is based on ananalysis of all infrared photometric observations carried out at LaSilla from 1979 until 1989 inclusive. The accuracy of the data (about0.02 mag. at J, H, K, L, and M) is similar to the one achieved at SAAOand CTIO. Comparisons with these systems, as well as with the AAO andMSSO systems, are made: it is shown that the ESO system is very close tothe other ones, with the exception of CTIOs.
| 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.
| An infrared search for primeval galaxies
A deep survey of two 'blank' fields at J and K (1.2 and 2.2 microns) hasbeen undertaken to search for primeval galaxies. The one objectdiscovered has infrared colors indicating that it is a faint foregroundgalaxy. The flux density of the brightest primeval galaxy which couldhave escaped detection, to 90 percent confidence, in the present surveyof about 1300 sq arcsec is about 33 microJy at K. This limit constrainsmodels of primeval galaxies by up to an order of magnitude over previousoptical searches, for galaxy formation redshifts z of between 5 and 10.
| Color evolution in high-redshift galaxies
The Simultaneous Photometer for Infrared and Visual Light has been usedto observe 40 radio- and 39 optically-selected giant elliptical galaxiesof known redshift in the 0.019-1.6 range. There is no indication in theresults obtained of differences between the colors of radio and nonradiogalaxies, with the exception of H-K in the z=0.2-0.4 range; the H-Kcolor is best fitted by a passively evolving model with little residualstar formation. Some galaxies exhibit strong blueward deviations. Thisbehavior is most easily explained by star formation episodes involvingsmall fractions of the total number of stars.
| The NASA infrared telescope facility Comet Halley monitoring program. I - Preperihelion results
The 1-20 microns IR monitoring program for Comet Halley whose resultsare presented covered January 1985 to January 1986, using a 7-arcsecaperture. It is noted that the comet's dust production was about 6million g/s at a heliocentric distance of 1 AU; the albedo of the dustin the coma was 3-4 percent. These results are compared with those forpreviously observed comets.
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Füllen |
| Right ascension: | 21h12m45.32s |
| Declination: | +02°38'33.9" |
| Apparent magnitude: | 6.995 |
| Distance: | 112.994 parsecs |
| Proper motion RA: | -28.2 |
| Proper motion Dec: | -18.9 |
| B-T magnitude: | 7.181 |
| V-T magnitude: | 7.011 |
Catalogs and designations:
|
