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Photometric Data (photometric + data)
Selected AbstractsAn analysis of the composite stellar population in M32,MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2009P. Coelho ABSTRACT We obtained long-slit spectra of high signal-to-noise ratio of the galaxy M32 with the Gemini Multi-Object Spectrograph at the Gemini-North telescope. We analysed the integrated spectra by means of full spectral fitting in order to extract the mixture of stellar populations that best represents its composite nature. Three different galactic radii were analysed, from the nuclear region out to 2 arcmin from the centre. This allows us to compare, for the first time, the results of integrated light spectroscopy with those of resolved colour,magnitude diagrams from the literature. As a main result we propose that an ancient and an intermediate-age population co-exist in M32, and that the balance between these two populations change between the nucleus and outside one effective radius (1reff) in the sense that the contribution from the intermediate population is larger at the nuclear region. We retrieve a smaller signal of a young population at all radii whose origin is unclear and may be a contamination from horizontal branch stars, such as the ones identified by Brown et al. in the nuclear region. We compare our metallicity distribution function for a region 1 to 2 arcmin from the centre to the one obtained with photometric data by Grillmair et al. Both distributions are broad, but our spectroscopically derived distribution has a significant component with [Z/Z,],,1, which is not found by Grillmair et al. [source] Massive stars exploding in a He-rich circumstellar medium , I. Type Ibn (SN 2006jc-like) eventsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008A. Pastorello ABSTRACT We present new spectroscopic and photometric data of the Type Ibn supernovae 2006jc, 2000er and 2002ao. We discuss the general properties of this recently proposed supernova family, which also includes SN 1999cq. The early-time monitoring of SN 2000er traces the evolution of this class of objects during the first few days after the shock breakout. An overall similarity in the photometric and spectroscopic evolution is found among the members of this group, which would be unexpected if the energy in these core-collapse events was dominated by the interaction between supernova ejecta and circumstellar medium. Type Ibn supernovae appear to be rather normal Type Ib/c supernova explosions which occur within a He-rich circumstellar environment. SNe Ibn are therefore likely produced by the explosion of Wolf,Rayet progenitors still embedded in the He-rich material lost by the star in recent mass-loss episodes, which resemble known luminous blue variable eruptions. The evolved Wolf,Rayet star could either result from the evolution of a very massive star or be the more evolved member of a massive binary system. We also suggest that there are a number of arguments in favour of a Type Ibn classification for the historical SN 1885A (S-Andromedae), previously considered as an anomalous Type Ia event with some resemblance to SN 1991bg. [source] The incidence of mid-infrared excesses in G and K giantsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2008Mark H. Jones ABSTRACT Using photometric data from the Two-Micron All-Sky Survey (2MASS) and GLIMPSE catalogues, I investigate the incidence of mid-infrared (mid-IR) excesses (,10 ,m) in G and K stars of luminosity class III. In order to obtain a large sample size, stars are selected using a near-IR colour,magnitude diagram. Sources which are candidates for showing mid-IR excess are carefully examined and modelled to determined whether they are likely to be G/K giants. It is found that mid-IR excesses are present at a level of (1.8 ± 0.4) × 10,3. While the origin of these excesses remains uncertain, it is plausible that they arise from debris discs around these stars. I note that the measured incidence is consistent with a scenario in which dust lifetimes in debris discs are determined by Poynting,Robertson drag rather than by collisions. [source] Spectroscopic and photometric observations of the selected Algol-type binaries , II.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008V2080 Cygni, V2365 Ophiuchi ABSTRACT This paper is the second in the planned series of investigations. We present new radial velocities and photometric observations of V2080 Cyg and V2365 Oph. New UBV photometric data and radial velocities were analysed for the systems' parameters. While V2080 Cyg consists of two nearly equal F-type main-sequence stars, V2365 Oph has two different components, namely an early A-type primary and a G-type secondary star. New ephemerides are calculated for both systems. The masses of the component stars have been derived as 1.19 ± 0.02 and 1.16 ± 0.02 M, for V2080 Cyg and 1.97 ± 0.02 and 1.06 ± 0.01 M, for V2365 Oph. The effective temperatures and reddening of the systems have been estimated from Johnson wide-band UBV photometric calibrations. The radii have been measured by simultaneous fitting the UBV light curves using Wilson,Devinney code and are 1.60 ± 0.01 R, for both components of V2080 Cyg and 2.19 ± 0.01 and 0.934 ± 0.004 R, for V2365 Oph. The absolute parameters of the stars in both systems lie within the same ranges in the mass,radius, mass,effective temperature, mass,luminosity and luminosity,effective temperature planes as in detached Algol systems. A comparison between the properties of the systems of interest and the predictions of theoretical evolutionary models is undertaken in the log g,logTeff, log R, log M and radius,log age diagrams. The model predictions match the measured properties of V2080 Cyg for an age of about 5.6 Gyr and a ,solar' metal abundance (Z= 0.019), indicating the components near the end of their core hydrogen-burning phases. However, the position of the components of V2365 Oph on the Hertzsprung,Russell (HR) diagram is best reproduced with evolutionary models for somewhat metal-deficient (Z= 0.004) stars. We found an age of about 700 Myr, with the primary component slightly evolved off the zero-age main-sequence and the secondary one still very close to it. From the basic stellar parameters we have also redetermined the distances to V2080 Cyg and V2365 Oph as 78 ± 1 and 251 ± 8 pc, which are in agreement with, and more accurate than, Hipparcos values. The observations show that at least one of the components of V2365 Oph is an intrinsic variable with a period and peak-to-peak amplitude of 0.07 d and 0.05 mag, respectively. In accordance with its position in the HR diagram, the primary component should be considered as a , Scuti star and it is believed to be the variable star in the system. [source] The remarkable properties of the symbiotic star AE CircinusMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2008R. Mennickent ABSTRACT We present new optical spectroscopy and photometry, Two-Micron All-Sky Survey (2MASS) infrared observations and 24 yr of combined American Association of Variable Star Observers (AAVSO) and Association Francaise des Observateurs d'Etoiles Variables (AFOEV) photometry of the symbiotic star candidate AE Cir. The long-term light curve is characterized by outbursts lasting several years and having a slow decline of ,2 × 10,4 mag d,1. The whole range of variability of the star in the V band is about 4 mag. The periodogram of the photometric data reveals strong signals at ,342 and 171 d. The presence of the emission feature at ,6830 Å at minimum and the detection of absorption lines of a ,K5 type star confirm the symbiotic classification and suggest that AE Cir is a new member of the small group of s-type yellow symbiotic stars. We estimate a distance of 9.4 kpc. Our spectrum taken at the high state shows a much flatter spectral energy distribution, the disappearance of the ,6830 Å emission feature and the weakness of the He ii 4686 emission relative to the Balmer emission lines. Our observations indicate the presence of emission-line flickering in time-scales of minutes in 2001. The peculiar character of AE Cir is revealed in the visibility of the secondary star at the high and low state, the light curve resembling a dwarf nova superoutburst and the relatively short low states. The data are hard to reconciliate with standard models for symbiotic star outbursts. [source] GHASP: an H, kinematic survey of spiral and irregular galaxies , V. Dark matter distribution in 36 nearby spiral galaxiesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008M. Spano ABSTRACT The results obtained from a study of the mass distribution of 36 spiral galaxies are presented. The galaxies were observed using Fabry,Perot interferometry as part of the GHASP survey. The main aim of obtaining high-resolution H, 2D velocity fields is to define more accurately the rising part of the rotation curves which should allow to better constrain the parameters of the mass distribution. The H, velocities were combined with low resolution H i data from the literature, when available. Combining the kinematical data with photometric data, mass models were derived from these rotation curves using two different functional forms for the halo: an isothermal sphere (ISO) and a Navarro,Frenk,White (NFW) profile. For the galaxies already modelled by other authors, the results tend to agree. Our results point at the existence of a constant density core in the centre of the dark matter haloes rather than a cuspy core, whatever the type of the galaxy from Sab to Im. This extends to all types the result already obtained by other authors studying dwarf and low surface brightness galaxies but would necessitate a larger sample of galaxies to conclude more strongly. Whatever model is used (ISO or NFW), small core radius haloes have higher central densities, again for all morphological types. We confirm different halo scaling laws, such as the correlations between the core radius and the central density of the halo with the absolute magnitude of a galaxy: low-luminosity galaxies have small core radius and high central density. We find that the product of the central density with the core radius of the dark matter halo is nearly constant, whatever the model and whatever the absolute magnitude of the galaxy. This suggests that the halo surface density is independent from the galaxy type. [source] Structural parameters of Mayall II = G1 in M31MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007J. Ma ABSTRACT Mayall II = G1 is one of the most luminous globular clusters (GCs) known in M31. New deep, high-resolution observations with the Advanced Camera for Surveys on the Hubble Space Telescope are used to provide accurate photometric data to the smallest radii yet. In particular, we present the precise variation of ellipticity and position angle, and of surface brightness for the core of the object. Based on these accurate photometric data, we redetermine the structural parameters of G1 by fitting a single-mass isotropic King model. We derive a core radius, rc= 0.21 ± 0.01 arcsec (= 0.78 ± 0.04 pc), a tidal radius, rt= 21.8 ± 1.1 arcsec (= 80.7 ± 3.9 pc), and a concentration index c= log (rt/rc) = 2.01 ± 0.02. The central surface brightness is 13.510 mag arcsec,2. We also calculate the half-light radius, at rh= 1.73 ± 0.07 arcsec (= 6.5 ± 0.3 pc). The results show that, within 10 core radii, a King model fits the surface brightness distribution well. We find that this object falls in the same region of the MV versus log Rh diagram as , Centauri, M54 and NGC 2419 in the Milky Way. All three of these objects have been claimed to be the stripped cores of now defunct dwarf galaxies. We discuss in detail whether GCs, stripped cores of dwarf spheroidals and normal dwarf galaxies form a continuous distribution in the MV versus log Rh plane, or if GCs and dwarf spheroidals constitute distinct classes of objects; we present arguments in favour of this latter view. [source] Narrow-band CCD photometry of giant H ii regionsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2002Guillermo Bosch We have obtained accurate CCD narrow-band H, and H, photometry of giant H ii regions (GEHRs) in M33, NGC 6822 and M101. Comparison with previous determinations of emission-line fluxes shows large discrepancies; their probable origins are discussed. Combining our new photometric data with global velocity dispersion (,) derived from emission linewidths, we review the relation. A re-analysis of the properties of the GEHRs included in our sample shows that age spread and the superposition of components in multiple regions introduce a considerable spread in the regression. Combining the information available in the literature regarding ages of the associated clusters, evolutionary footprints on the interstellar medium, and kinematical properties of the knots that build up the multiple GEHRs, we find that a subsample , which we refer to as young and single GEHRs , do follow a tight relation in the plane. [source] OGLE observations of four X-ray binary pulsars in the Small Magellanic CloudMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2000M. J. Coe This paper presents analysis and interpretation of OGLE photometric data of four X-ray binary pulsar systems in the Small Magellanic Cloud (SMC): 1WGA J0054.9-7226, RX J0050.7-7316, RX J0049.1-7250 and 1SAX J0103.2-7209. In each case, the probable optical counterpart is identified on the basis of its optical colours. In the case of RX J0050.7-7316 the regular modulation of its optical light curve appears to reveal an ellipsoidal modulation with a period of 1.416 d. Using reasonable masses for the neutron star and the B star, we show that the amplitude and relative depths of the minima of the I -band light curve of RX J0050.7-7316 can be matched with an ellipsoidal model where the B star nearly fills its Roche lobe. For mass ratios in the range of 0.12 to 0.20, the corresponding best-fitting inclinations are about 55° or larger. The neutron star would be eclipsed by the B star at inclinations larger than ,60° for this particular mass ratio range. Thus RX J0050.7-7316 is a good candidate system for further study. In particular, we would need additional photometry in several colours, and most importantly, radial velocity data for the B star before we could draw more quantitative conclusions about the component masses. [source] Transformations between the 2MASS, SDSS, and BVI photometric systems for late-type giantsASTRONOMISCHE NACHRICHTEN, Issue 8 2010E. Yaz Abstract We present colour transformations from Two Micron All Sky Survey (2MASS) photometric system to Johnson-Cousins system and to Sloan Digital Sky Survey (SDSS) system for late-type giants and vice versa. The giant star sample was formed using surface gravity constraints (2 < log g , 3) to Cayrel de Strobel et al.'s (2001) spectroscopic catalogue. 2MASS, SDSS and Johnson-Cousins photometric data was taken from Cutri et al. (2003), Ofek (2008), and van Leeuwen (2007), respectively. The final sample was refined applying the following steps: (1) the data were dereddened, (2) the sample stars selected are of the highest photometric quality. We give two-colour dependent transformations as a function of metallicity as well as independent of metallicity. The transformations provide absolute magnitudes and distance determinations which can be used in space density evaluations at relatively short distances where some or all of the SDSS magnitudes of late-type giants are saturated (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] New photometry and astrometry of the isolated neutron star RX J0720.4,3125 using recent VLT/FORS observations,ASTRONOMISCHE NACHRICHTEN, Issue 3 2010T. Eisenbeiss Abstract Since the first optical detection of RX J0720.4,3125 various observations have been performed to determine astrometric and photometric data. We present the first detection of the isolated neutron star in the V Bessel filter to study the spectral energy distribution and derive a new astrometric position. At ESO Paranal we obtained very deep images with FORS 1 (three hours exposure time) of RX J0720.4,3125 in the V Bessel filter in January 2008. We derive the visual magnitude by standard star aperture photometry. Using sophisticated resampling software we correct the images for field distortions. Then we derive an updated position and proper motion value by comparing its position with FORS 1 observations of December 2000. We calculate a visual magnitude of V = 26.81 ± 0.09 mag, which is seven times in excess of what is expected from X-ray data, but consistent with the extant U, B, and R data. Over about a seven year epoch difference we measured a proper motion of , = 105.1 ± 7.4 mas yr,1 towards , = 296.951° ± 0.0063° (NW), consistent with previous data (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Luminosity function of galaxies in rich and poor galaxy clustersASTRONOMISCHE NACHRICHTEN, Issue 9-10 2009J. Krywult Abstract Using photometric data from SDSS survey we study the galaxy luminosity function in the 75 rich and poor Abell clusters. The integrated Schechter functions were fitted to unbinned data in the four g, r, i, and z photometric passbands. We find that the luminosity function differs with Abell richness class (R). In all bands the faint-end slope , is steeper in poor clusters than in rich clusters. Moreover, the value of characteristic magnitude M * decreasing with richness class R (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Ultraviolet color-magnitude relation of early-type dwarf galaxies in the Virgo clusterASTRONOMISCHE NACHRICHTEN, Issue 9-10 2009S. Kim Abstract We present ultraviolet (UV) color-magnitude relations (CMRs) for dwarf ellipticals (dEs) and dwarf lenticulars (dS0s) in the Virgo cluster. We used the Galaxy Evolution Explorer (GALEX) GR3 photometric data in far-ultraviolet (FUV) and near-ultraviolet (NUV) passbands combined with SDSS DR5 data. We found that dS0s as well as peculiar dEs (dEs with blue center and disk) found by Lisker et al. (2006a, b) show distinct locus from that of ordinary dEs in UV CMRs. The dS0s and peculiar dEs have bluer UV colors than ordinary dEs at a fixed optical luminosity. Furthermore, UV colors of dEs in outer region of the cluster are systematically bluer than those in inner region. Since UV flux is sensitive to the presence of young stellar population from recent star formation activity, our results suggest that there are different star formation histories among different subsample of early-type dwarf galaxies in Virgo cluster concerning their morphology and environmental effect (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Complexity in small-scale dwarf spheroidal galaxies , Ludwig Biermann Award Lecture 2008ASTRONOMISCHE NACHRICHTEN, Issue 7 2009A. KochArticle first published online: 17 JUL 200 Abstract Our knowledge about the dynamics, the chemical abundances and the evolutionary histories of the more luminous dwarf spheroidal (dSph) galaxies is constantly growing. However, very little is known about the enrichment of the ultra-faint systems recently discovered in large numbers in large sky surveys. Current low-resolution spectroscopy and photometric data indicate that these galaxies are highly dark matter dominated and predominantly metal poor. On the other hand, recent high-resolution abundance analyses indicate that some dwarf galaxies experienced highly inhomogeneous chemical enrichment, where star formation proceeds locally on small scales. In this article, I will review the kinematic and chemical abundance information of the Milky Way satellite dSphs that is presently available from low- and high resolution spectroscopy. Moreover, some of the most peculiar element and inhomogeneous enrichment patterns will be discussed and related to the question of to what extent the faintest dSph candidates could have contributed to the Galactic halo, compared to more luminous systems (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photometric monitoring of the young star Par 1724 in Orion,ASTRONOMISCHE NACHRICHTEN, Issue 5 2009R. Neuhäuser Abstract We report new photometric observations of the ,200 000 year old naked weak-line run-away T Tauri star Par 1724, located north of the Trapezium cluster in Orion. We observed in the broad band filters B, V, R, and I using the 90 cm Dutch telescope on La Silla, the 80 cm Wendelstein telescope, and a 25 cm telescope of the University Observatory Jena in Großschwabhausen near Jena. The photometric data in V and R are consistent with a ,5.7 day rotation period due to spots, as observed before between 1960ies and 2000. Also, for the first time, we present evidence for a long-term 9 or 17.5 year cycle in photometric data (V band) of such a young star, a cycle similar to that to of the Sun and other active stars (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Pulsation and orbit of AU PegasiASTRONOMISCHE NACHRICHTEN, Issue 8 2007M. Jurkovic Abstract AU Pegasi is a pulsating star in a spectroscopic binary system with an orbital period of 53.26 days. Between 1960 and 1990 an extremely rapid period increase was observed in the value of the pulsation period, but in the last 15 years the observation show that the period set in 2.411 days. Fourier analysis of photometric data obtained during the ASAS project and those taken at the Piszkéstet, Mountain Station of the Konkoly Observatory during 1994,2005 indicate that AU Pegasi is pulsating in two modes simultaneously, and the ratio of the frequencies of the two modes is 0.706, a value common for double-mode classical Cepheids. A careful analysis of other photometric observations obtained during the era of the strong period increase also revealed existence of a second mode. This may suggest that this star is not a Type II Cepheid, despite its galactic position. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Identifications of FIRST radio sources in the NOAO Deep Wide-Field SurveyASTRONOMISCHE NACHRICHTEN, Issue 6 2007K. El Bouchefry Abstract In this paper we present the results of an optical and near infrared identification of 514 radio sources from the FIRST survey (Faint Images of the Radio Sky Survey at Twenty centimetres) with a flux-density limit of 1 mJy in the NOAO Deep Wide-Field Survey (NDWFS) Boötes field. Using optical (Bw, R, I) and K band data with approximate limits of Bw , 25.5 mag, R , 25.8 mag, I , 25.5 mag and K , 19.4 mag, optical counterparts have been identified for 378 of 514 FIRST radio sources. This corresponds to an identification rate of 34% in four bands (BwRIK), 60% in optical bands (BwRI) and 74% in the I band. Photometric redshifts for these sources have been computed using the hyperz code. The inclusion of quasar template spectra in hyperz is investigated. We note that the photometric data are, in many cases, best matched to templates with very short star-formation timescales and the inferred ages of identified galaxies depend strongly on the assumptions about the star-formation timescale. The redshifts obtained are fairly consistent with those expected from the K - z relation for brighter radio sources but there is more scatter in the K - z diagram at z < 1. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] On-line database of photometric observations of magnetic chemically peculiar starsASTRONOMISCHE NACHRICHTEN, Issue 1 2007Z. Mikulá Abstract We present our extensive project of the On-line database of photometric observations of magnetic chemically peculiar stars to collect published data of photometric observations of magnetic chemically peculiar (mCP) stars in the optical and near IR regions. Now the nascent database contains more than 107 000 photometric measurements of 102 mCP stars and will be continually supplemented with published or new photometric data on these and about 150 additional mCP stars. This report describes the structure and organization of the database. Moreover, for the all included data we estimated the error of measurements and the effective amplitudes of the light curves. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Radial velocity and light curves analysis of the eclipsing binary NN VirASTRONOMISCHE NACHRICHTEN, Issue 9 2004R. Pazhouhesh Abstract The eclipsing binary NN Vir is a short period system showing an EW-type light curve. Photometric observations of NN Vir were done by Gomez-Ferrellad & Garcia-Melendo (1997) at Esteve Duran Observatory. We used photometric data of NN Vir for light curve analysis. The available spectroscopic data of NN Vir is new and we also used the first radial velocity data of this system obtained by Rusinski & Lu (1999) for analysis. The radial velocity and light curves analysis was made with the latest version ofWilson program(1998) and the geometric and physical elements of the system are derived. By searching the simultaneous solutions of the system, we have determined the masses and radii of the components : 1.89(M,) and 1.65(R,) for the primary component; 0.93(M,) and 1.23(R,) for the secondary component. We estimated effective temperatures of 7030(K) for the primary and 6977(K) for the secondary component. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Time-series photometric spot modelling , VI.ASTRONOMISCHE NACHRICHTEN, Issue 3 2003A new computer code, its application to 23 years of photometry of the active giant IM Pegasi Abstract We present and apply a new computer program named SpotModeL to analyze single and multiple bandpass photometric data of spotted stars. It is based on the standard analytical formulae from Budding and Dorren. The program determines the position, size, and temperature of up to three spots by minimizing the fit residuals with the help of the Marquardt-Levenberg non-linear least-squares algorithm. We also expand this procedure to full time-series analysis of differential data, just as real observations would deliver. If multi-bandpass data are available, all bandpasses can be treated simultaneously and thus the spot temperature is solved for implicitly. The program may be downloaded and used by anyone. In this paper, we apply our code to an ,23 year long photometric dataset of the spotted RS CVn giant IM Peg. We extracted and modelled 33 individual light curves, additionally, we fitted the entire V dataset in one run. The resulting spot parameters reflect the long term light variability and reveal two active longitudes on the substellar point and on the antipode. The radius and longitude of the dominant spot show variations with 29.8 and 10.4 years period, respectively. Our multicolour data suggests that the spot temperature is increasing with the brightening of the star. The average spot temperature from V, IC is 3550 ± 150 K or approximately 900 K below the effective temperature of the star. [source] | ||||||||||