Near-infrared Properties Research Articles

A Principle Component Analysis of Galaxy Properties from a Large, Gas-Selected Sample

Disney et al. (2008) have found a striking correlation among global parameters of Hi-selected galaxies and concluded that this is in conflict with the CDM model. Considering the importance of the issue, we reinvestigate the problem using the principal component analysis on a fivefold larger sample and additional near-infrared data. We use databases from the Arecibo Legacy Fast AreciboL-band Feed Array Survey for the gas properties, the Sloan Digital Sky Survey for the optical properties, and the Two Micron All Sky Survey for the near-infrared properties. We confirm that the parameters are indeed correlated where a single physical parameter can explain 83% of the variations. When color (g-i) is included, the first component still dominates but it develops a second principal component. In addition, the near-infrared color (i-J) shows an obvious second principal component that might provide evidence of the complex old star formation. Based on our data, we suggest that it is premature to pronounce the failure of the CDM model and it motivates more theoretical work.

Spectral definition of the macro-algae Ulva curvata in the back-barrier bays of the Eastern Shore of Virginia, USA

We have developed methods to determine the visible (VIS) to near-infrared (NIR) spectral properties of thalli and epiphytes of bloom-forming and green macrophyte Ulva curvata in back-barrier lagoons in Virginia, USA. A 2% increase in NIR thalli reflectance from winter to summer (ca. 9.5%) matched the drop in summer NIR transmittance (ca. 90%). In contrast, summer and winter VIS reflectance (reaching 6%) were nearly identical while winter transmittance (ca. 85%) was 10–20% higher. NIR absorption remained at 5% but VIS absorption increased by 10–20% from winter to summer. Replicate consistency substantiated the high transmittance difference indicating thallus composition changed from summer to winter. Epiphytes increased thallus reflectance (<ca. 4%) and decreased transmittance (<ca. 10%) and exhibited broadband VIS and NIR absorptions in summer and selective peaks in winter. A simulation coupling water extinction with thallus reflectance and transmittance found seven submerged thalli maximized the surface reflectance enhancement (ca. 2.5%).

Study on Preparation and Near-Infrared Reflective Properties of NaZnPO&lt;sub&gt;4&lt;/sub&gt;

NaZnPO4was prepared by heat-treating precursor with Zn(NO3)2٠6H2O、H3PO4and anhydrous sodium carbonate as raw materials by co-precipitation method, and it was characterized with UV/VIS spectrophotometer、X-ray diffraction (XRD). The experiment results shown that the near-infrared reflection property of NaZnPO4was very good. when the heat treatment temperature of preparation of NaZnPO4was range from 400°C to 800°C, near-infrared reflection properties of products were similar. Among them, the products with the heat treatment of 600°C has the best near-infrared reflection property,which is reached up to 95.2% in average,while the near-infrared reflection of TiO2is 74.1% in average.

Porphyrin-Cross-Linked Hydrogel for Fluorescence-Guided Monitoring and Surgical Resection

We demonstrate that porphyrins can be used as efficient cross-linkers to generate a new class of hydrogels with enabling optical properties. Tetracarboxylic acid porphyrins reacted with PEG diamines to form a condensation polyamide in a range of appropriate conditions, with respect to reaction time, diisopropylethylamine initiator concentration, porphyrin-to-PEG ratio, porphyrin concentration, and PEG size. The network structure of the hydrogel maintained a porphyrin spacing that prevented excessive fluorescence self-quenching despite high porphyrin density. The near-infrared properties readily enabled low background, noninvasive fluorescence monitoring of the implanted hydrogel in vivo, as well as its image-guided surgical removal in real time using a low-cost fluorescence camera prototype. Emission could be tuned by incorporating copper metalloporphyrins into the network. The approach of creating hydrogels using cross-linking porphyrin comonomers creates opportunities for new polymer designs with strong optical character.

The VMC survey

The VISTA Magellanic Cloud (VMC) survey is assembling a deep, multi-epoch atlas of YJKs photometry across the Magellanic Clouds. Prior to the VMC survey only the brightest Magellanic Cloud PNe (MCPNe) were accessible at near-infrared (NIR) wavelengths. It is now possible for the first time to assemble the NIR properties of MCPNe and to identify contaminating non-PNe mimics which are best revealed at NIR wavelengths (e.g. HII regions and symbiotic stars). To maintain the unique scientific niche that MCPNe occupy these contaminants must be removed. Here we conduct a VMC-led, multi-wavelength study of 102 objects previously classified as PNe that are located within the first six VMC tiles observed. We present images, photometry, lightcurves, diagnostic colour-colour diagrams and spectral energy distributions used to analyse the entire sample. At least five PNe have newly resolved nebula morphologies, a task previously only possible with the HST. A total 45/67 (67%) of Reid & Parker (RP) catalogued objects were reclassified as non-PNe, most of which were located in the vicinity of 30 Doradus. This sample included 16 field stars, 5 emission line stars, 19 HII regions, 4 symbiotic star candidates and 1 young stellar object. We discuss possible selection effects responsible for their inclusion in the RP catalogue and the implications for binary central star surveys targeting LMC PNe. A total of five new LMC symbiotic star candidates identified, compared to eight previously known, underlines the important role the VMC survey will have in advancing Magellanic symbiotic star studies.

NEAR-INFRARED PROPERTIES OF THE X-RAY-EMITTING YOUNG STELLAR OBJECTS IN THE CARINA NEBULA

Abbreviated Abstract: The near-infrared study of the Carina Nebula in this paper builds on the results of the Chandra Carina Complex Project (CCCP), that detected 14368 X-ray sources in the 1.4 square-degree survey region, an automatic source classification study that classified 10714 of these as very likely young stars in Carina, and an analysis of their clustering properties. We used HAWK-I at the ESO VLT to conduct a very deep near-IR survey with sub-arcsecond angular resolution, covering about 1280 square-arcminutes. The HAWK-I images reveal more than 600000 individual infrared sources, whereby objects as faint as J ~ 23, H ~ 22, and Ks ~ 21 are detected at S/N >= 3. While less than half of the Chandra X-ray sources have counterparts in the 2MASS catalog, the ~5 mag deeper HAWK-I data reveal infrared counterparts to 6636 (= 88.8%) of the 7472 Chandra X-ray sources in the HAWK-I field. We analyze near-infrared color-color and color-magnitude diagrams to derive information about the extinctions, infrared excesses, ages, and masses of the X-ray selected objects. The near-infrared properties agree well with the results of the automatic X-ray source classification. The shape of the K-band luminosity function of the X-ray selected Carina members agrees well with that derived for the Orion Nebula Cluster, suggesting that, down to the X-ray detection limit around 0.5-1 Msun, the shape of the IMF in Carina is consistent with that in Orion (and thus the field IMF). The fraction of stars with near-infrared excesses is rather small, <=10%, but shows considerable variations between individual parts of the complex. The distribution of extinctions for the diskless stars ranges from ~1.6 mag to ~6.2 mag (central 80th percentile), clearly showing a considerable range of differential extinction between individual stars in the complex.

New R Coronae Borealis stars discovered in OGLE-III Galactic bulge fields from their mid- and near-infrared properties

An R Coronae Borealis (RCB) star is a rare type of supergiant star that is increasingly thought to be the evolved merger product of two white dwarfs. Recently, many of them have been found distributed in a thin disk structure embedded inside the Galactic Bulge. This unexpected high density can give us more insight into the nature and age of RCB stars. We applied and tested successfully a new technique to find RCB stars based on the particular infrared emission. We demonstrated that RCB stars can now be found without the need of a light curve analysis, and therefore outside optically monitored fields. The selection of RCB candidates was based on their near-infrared excess and on particular mid-infrared emission of RCB shells, using photometric data from the 2MASS and Spitzer/GLIMPSE surveys. The OGLE light curves of all RCB candidates were then inspected visually and the ones presenting large and fast declines were followed-up spectroscopically . We discovered two new R Coronae Borealis stars, but also propose four new candidates. We stress that all of the 7 known RCB stars located in both Spitzer/GLIMPSE and OGLE-III fields were re-discovered, which indicates the high efficiency of our analysis. The proposed new technique to find RCB stars has been successful. It can now be extented to larger area, specially where the instellar extinction is too high to have been monitored by microlensing surveys, i.e the inner part of the Galactic Bulge.

2MASS NEAR-IR COLOR-MAGNITUDE DIAGRAM OF THE OLD OPEN CLUSTER KING 11

We study near-infrared properties of the old open cluster King 11, based on the 2MASS photometric data. We determine the location of the red giant clump(RGC) in the (K, J - K) colo-magnitude diagram and derive the distance modulus of King 11 to be <TEX>$(m-M)_0$</TEX> = <TEX>$12.50{\pm}0.10$</TEX> using the mean K magnitude of RGC. From the red giant branch slope - [Fe/H] relation we obtain the metallicity of this cluster, [Fe/H]=<TEX>$-0.17{\pm}0.07$</TEX>. The age and interstellar reddening of this cluster are estimated to be log t = <TEX>$9.48{\pm}0.05$</TEX>, E(B-V)=<TEX>$0.90{\pm}0.03$</TEX>, by applying Padova isochrone fits to the data.

Near-infrared broadband emission spectroscopic properties of Bi: α-BaB2O4 single crystal induced by electron irradiation

Bi:α-BaB2O4 crystal samples are grown by the traditional Czochralski method and the obtained samples are irradiated by electron beam. Absorption and emission spectra of the samples are measured at room temperature before and after their electron irradiation. Under 808 nm LD excitation, broadband (FWHM at 52 nm) near-infrared emissions centered at about 1135 nm are observed in electron-irradiated Bi:α-BaB2O4 samples. Both the emissions are believed to be due to Bi+ ions. Electron beam helps to reduce Bi3+ and Bi2+ into univalence. The formation processes in the samples with different radiation doses are not the same, which is primarily discussed in this work.

Near-Infrared Properties of Irregular Dwarf Galaxies in Nearby Galaxy Groups

The environmental effects on galaxy evolution have recently been disputed based on large SDSS galaxy samples but these effects are still expected to be strong for low-mass galaxies. We obtained deep near-infrared imaging of irregular dwarfs in Cen A, M 81 and Sculptor groups – spanning a range of galaxy density, – and we study the properties of these dwarfs, i.e. abundance, chemical evolution, and structural parameters. Here we give a preliminary assessment of the structural parameters for these galaxies.

Study on the Near-infrared Absorption Properties of ZnGeP&lt;SUB&gt;2&lt;/SUB&gt; Single Crystals

采用布里奇曼法生长了磷化锗锌晶体, 晶体毛坯尺寸达直径20mm×90mm, 选取晶体尾部、晶体中部、籽晶端三个部位厚度为4.0mm的抛光晶片作为测试样品. 从实验和理论上研究与分析了晶体的近红外吸收特性. 实验结果显示: 晶体透过率由尾部至近籽晶端逐渐增大, 表明晶体近红外吸收由尾部至近籽晶端逐渐减小, 这是由于晶体内缺陷密度发生了改变, 且晶体内本征点缺陷分布比例不均衡, 进而导致晶体的近红外吸收产生差异. 理论上计算了磷化锗锌晶体施主缺陷和受主缺陷的吸收光谱. 计算结果表明: 受主缺陷对磷化锗锌晶体吸收光谱产生的影响大于施主缺陷.

Near-infrared properties of metal-poor globular clusters in the Galactic bulge direction

Aims. J, H, and K' images obtained from the near-infrared imager CFHTIR on the Canada-France-Hawaii Telescope are used to derive the morphological parameters of the red giant branch (RGB) in the near-infrared color-magnitude diagrams for 12 metal-poor globular clusters in the Galactic bulge direction. Using the compiled data set of the RGB parameters for the observed 12 clusters, in addition to the previously studied 5 clusters, we discuss the properties of the RGB morphology for the clusters and compare them with the calibration relations for the metal-rich bulge clusters and the metal-poor halo clusters. Methods. The photometric RGB shape indices such as colors at fixed magnitudes of MK = MH = (-5.5, -5, -4, and -3), magnitudes at fixed colors of (J - K)o = (J - H)o = 0.7, and the RGB slope are measured from the fiducial normal points defined in the near- infrared color-magnitude diagrams for each cluster. The magnitudes of RGB bump and tip are also estimated from the differential and cumulative luminosity functions of the selected RGB stars. The derived RGB parameters have been used to examine the overall behaviors of the RGB morphology as a function of cluster metallicity. Results. The correlations between the near-infrared photometric RGB shape indices and the cluster metallicity for the programme clusters compare favorably with the previous observational calibration relations for metal-rich clusters in the Galactic bulge and the metal-poor halo clusters. The observed near-infrared magnitudes of the RGB bump and tip for the investigated clusters are also in accordance with the previous calibration relations for the Galactic bulge clusters.

Near-infrared properties of periodically poled KTiOPO4 and stoichiometric MgO-doped LiTaO3 crystals for high power optical parametric oscillation with femtosecond pulses

A thorough theoretical analysis of the near-infrared properties of periodically poled KTiOPO4 (PPKTP) and stoichiometric MgO-doped LiTaO3 (MgO:PPSLT) crystals for optical parametric oscillation with excitation at 1 μm is presented. To the best of our knowledge, the optical, phasematching, wavelength tuning, and dispersive properties of these crystals for parametric interactions are discussed in detail for the first time. In addition, a new design for high power parametric devices based on PPKTP or MgO:PPSLT crystals with ultrafast Yb-ion laser pump is proposed. The results form a useful reference for the selection of materials and operating conditions for the practical design of high power femtosecond optical parametric oscillators with excitation at 1 μm.

An effect of “scattering by absorption” observed in near-infrared properties of nanoporous silica

The obtained spectroscopic data for absorption and scattering characteristics of nanoporous silica in the wavelength range from 0.25 to 7 μm are analyzed on the basis of the Mie theory. It is shown that aggregates of primary nanoparticles are responsible for relatively high scattering in the short-wave range from 0.25 to 1.4 μm. But the presence of the aggregates and micron-size cracks in the samples cannot explain unusual behavior of scattering in the long-wave part of the spectral range. The attention of the authors is focused on understanding of strong scattering peaks observed at exactly the same wavelengths as the infrared absorption peaks of bulk silica: at λ=2.9, 5.3, and 6.1 μm. The known physical effect of “scattering by absorption” is considered as a source of these scattering peaks. It means that absorption centers are assumed to be not uniformly distributed in the nanoporous matrix but collected in some micron-size regions. The estimates based on this hypothesis are supported by the fact that near-infrared absorption peaks are produced by silanol groups which may be nonuniformly distributed in the hydroxylated nanoporous silica.

Preparation and near-infrared luminescence properties of Bi-doped BaF2 crystal

Bi2O3:BaF2 and BiF3:BaF2 crystals were prepared by TGT (temperature gradient method). Near-infrared broadband luminescence was observed in as-grown Bi2O3:BaF2 crystal. The emission band peaks at 961 nm in the range of 850—1250 nm，with FWHM about 202 nm. The luminescence of Bi2+ and Bi3+ ions in the visible region was observed in BiF3:BaF2 crystal, but there was no near-infrared emission. Then the BiF3: BaF2 crystal was exposed to γ-rays in order to reduce valence states of Bi ions. Near-infrared broadband luminescence was observed in γ-irradiated BiF3:BaF2 crystal. The emission band peaks at 1135 nm in the range of 850—1500 nm，with FWHM about 192 nm. The mechanisms of near-infrared luminescence in Bi2O3:BaF2 crystals and γ-irradiated BiF3:BaF2 crystals were discussed.

Near-infrared properties of 12 globular clusters towards the inner bulge of the Galaxy

We present near-IR Colour-Magnitude diagrams and physical parameters for a sample of 12 galactic globular clusters located toward the inner Bulge region. For each cluster we provide measurements of the reddening, distance, photometric metallicity, luminosity of the horizontal branch red clump, and of the red giant branch bump and tip. The sample discussed here together with that presented in Valenti, Ferraro & Origlia (2007) represent the largest homogeneous catalog of Bulge globular clusters (comprising ~ 80% of the entire Bulge cluster population) ever studied. The compilation is available in electronic form on the World Wide Web (http://www.bo.astro.it/~GC/ir_archive)

EX Lupi in quiescence

EX Lup is the prototype of EXors, a subclass of low-mass pre-main sequence stars whose episodic eruptions are attributed to temporarily increased accretion. In quiescence the optical and near-infrared properties of EX Lup cannot be distinguished from those of normal T Tau stars. Here we investigate whether it is the circumstellar disk structure which makes EX Lup an atypical Class II object. During outburst the disk might undergo structural changes. Our characterization of the quiescent disk is intended to serve as a reference to study the physical changes related to one of EX Lupi's strongest known eruptions in 2008 Jan-Sep. We searched the literature for photometric and spectroscopic observations including ground-based, IRAS, ISO and Spitzer data. After constructing the optical-infrared spectral energy distribution (SED), we compared it with the typical SEDs of other young stellar objects and modeled it using the Monte Carlo radiative transfer code RADMC. A mineralogical decomposition of the 10 micron silicate emission feature and also the description of the optical and near-infrared spectra were performed. The SED is in general similar to that of a typical T Tauri star, though above 7 micron EX Lup emits higher flux. The quiescent phase data suggest low level variability in the optical-mid-infrared domain. Integrating the optical and infrared fluxes we derived a bolometric luminosity of 0.7 L_Sun. The 10 micron silicate profile could be fitted by a mixture consisting of amorphous silicates, no crystalline silicates were found. A modestly flaring disk model with a total mass of 0.025 M_Sun and an outer radius of 150 AU was able to reproduce the observed SED. The derived inner radius of 0.2 AU is larger than the sublimation radius, and this inner gap sets EX Lup aside from typical T Tauri stars.

Near-infrared luminescent properties and natural lifetime calculation of a novel Er3+ complex

in this communication, a novel Er3+ complex Er(PT)(3)TPPO [PT = 1-phenyl-3-methyl-4-tert-butylbenzoyl-5-pyrazolone, TPPO = triphenyl phosphine oxide] is successfully synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. Its optical properties and the energy transfer process from the ligand PT to the Er3+ ion are investigated, the typical near-infrared (NIR) luminescence (centered at around 1530 nm) is attributed to the I-4(13/2) -> I-4(15/2) transition of Er3+ ion which results from the efficient energy transfer from PT to Er3+ ion (an antenna effect). The wider full width at half maximum (78 nm) peaked at 1530 nm in the emission spectrum and the Judd-Ofelt theory calculation on the radiative properties suggest that Er(PT)(3)TPPO should be a promising candidate for tunable lasers and planar optical amplifiers.

Mid-Infrared and Near-Infrared Spectral Properties of Mycorrhizal and Non-Mycorrhizal Root Cultures

We investigated the Fourier-transformed mid-infrared (MIR) and near-infrared (NIR) spectroscopic properties of mycorrhizal (M) and non-mycorrhizal (NM) carrot roots with the goal of finding infrared markers for colonization by arbuscular mycorrhizal (AM) fungi. The roots were cultured with or without the AM fungus Glomus intraradices under laboratory conditions. A total of 50 M and NM samples were produced after pooling subsamples. The roots were dried, ground, and scanned separately for the NIR and MIR analyses. The root samples were analyzed for fatty acid composition in order to confirm mycorrhizal infection and to determine the presence of fatty acid markers. Besides the roots, fatty acid standards, pure cultures of saprophytic fungi, and chitin were also scanned in order to identify spectral bands likely to be found in M samples. Principal components analysis (PCA) was used to illustrate spectral differences between the M and NM root samples. The NIR analysis achieved good resolution with the raw spectral data and no pretreatment was needed to obtain good resolution in the PCA analysis of the NIR data. Standard normal variate and detrending pretreatment improved the resolution between M and NM in the MIR range. The PCA loadings and/or the spectral subtraction of selected samples showed that M roots are characterized by absorbances at or close to 400 cm(-1), 1100-1170 cm(-1), 1690 cm(-1), 2928 cm(-1), and 5032 cm(-1). The NM samples had characteristic absorbances at or near 1734 cm(-1), 3500 cm(-1), 4000 cm(-1), 4389 cm(-1), and 4730 cm(-1). Some of the bands that differentiate M from NM roots are prominent in the spectra of pure fungal cultures, chitin, and fatty acids. Our results show that mycorrhizal and nonmycorrhizal root tissues can be differentiated via MIR and NIR spectra with the advantage that the same samples can then be used for other analyses.

ChandraandXMM-Newtonobservations of the low-luminosity X-ray pulsators SAX J1324.4−6200 and SAX J1452.8−5949

We present results from our Chandra and XMM–Newton observations of two low-luminosity X-ray pulsators SAX J1324.4−6200 and SAX J1452.8−5949 which have spin periods of 172 and 437 s, respectively. The XMM–Newton spectra for both sources can be fitted well with a simple power-law model of photon index, Γ∼ 1.0. A blackbody model can equally well fit the spectra with a temperature, kT∼ 2 keV, for both sources. During our XMM–Newton observations, SAX J1324.4−6200 is detected with coherent X-ray pulsations at a period of 172.86 ± 0.02 s while no pulsations with a pulse fraction greater than 18 per cent (at 95 per cent confidence level) in 0.2–12 keV energy band are detected in SAX J1452.8−5949. The spin period of SAX J1324.4−6200 is found to be increasing on a time-scale of which would suggest that the accretor is a neutron star and not a white dwarf. Using subarcsec spatial resolution of the Chandra telescope, possible counterparts are seen for both sources in the near-infrared images obtained with the son of infrared spectrometer and array camera (SOFI) instrument on the New Technology Telescope. The X-ray and near-infrared properties of SAX J1324.4−6200 suggest it to be a persistent high-mass accreting X-ray pulsar at a distance ≤8 kpc. We identify the near-infrared counterpart of SAX J1452.8−5949 to be a late-type main-sequence star at a distance ≤10 kpc, thus ruling out SAX J1452.8−5949 to be a high-mass X-ray binary. However, with the present X-ray and near-infrared observations, we cannot make any further conclusive conclusion about the nature of SAX J1452.8−5949.