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Photometric Observations (photometric + observation)
Selected AbstractsPhotometric observations of the Type Ia SN 2002er in UGC 10743MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2004G. Pignata ABSTRACT Extensive light and colour curves for the Type Ia supernova (SN Ia) SN 2002er are presented as part of the European Supernova Collaboration. We have collected UBVRI photometry from 11 different telescopes covering the phases from 7 d before until 619 d after maximum light. Corrections for the different instrumental systems and the non-thermal spectrum of the supernova (S -corrections) have been applied. With the densely sampled light curves we can make detailed comparisons to other well-observed objects. SN 2002er most closely resembles SN 1996X after maximum, but clearly shows a different colour evolution before peak light and a stronger shoulder in V and R bands compared to other well-observed SNe Ia. In particular, the rise time appears to be longer than what is expected from the rise time versus decline rate relation. We use several methods to determine the reddening towards SN 2002er based on the colour evolution at near peak and at late phases. The uvoir (bolometric) light curve shows great similarity with SN 1996X, but also indications of a higher luminosity, longer rise time and a more pronounced shoulder 25 d past maximum. The interpretation of the light curves was carried out with two independent light curve codes. Both find that given the luminosity of SN 2002er the 56Ni mass exceeds 0.6 M, with preferred values near 0.7 M,. Uncertainties in the exact distance to SN 2002er are the most serious limitation of this measurement. The light-curve modelling also indicates a high level of mixing of the nickel in the explosion of SN 2002er. [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] 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] Physical parameters of the O6.5V+B1V eclipsing binary system LS 1135MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006E. Fernández Lajús ABSTRACT The ,All Sky Automated Survey' (ASAS) photometric observations of LS 1135, an O-type single-lined binary (SB1) system with an orbital period of 2.7 d, show that the system is also eclipsing performing a numerical model of this binary based on the Wilson,Devinney method. We obtained an orbital inclination . With this value of the inclination, we deduced masses M1, 30 ± 1 M, and M2, 9 ± 1 M,, and radii R1, 12 ± 1 R, and R2, 5 ± 1 R, for primary and secondary components, respectively. Both the components are well inside their respective Roche lobes. Fixing the Teff of the primary to the value corresponding to its spectral type (O6.5V), the Teff obtained for the secondary component corresponds approximately to a spectral type of B1V. The mass ratio M2/M1, 0.3 is among the lowest known values for spectroscopic binaries with O-type components. [source] A non-main-sequence secondary in SY CancriMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2005Robert Connon Smith ABSTRACT Simultaneous spectroscopic and photometric observations of the Z Cam type dwarf nova SY Cancri were used to obtain absolute flux calibrations. A comparison of the photometric calibration with a wide-slit spectrophotometric calibration showed that either method is equally satisfactory. A radial velocity study of the secondary star, made using the far-red Na i doublet, yielded a semi-amplitude of K2= 127 ± 23 km s,1. Taking the published value of 86 ± 9 km s,1 for K1 gives a mass ratio of q=M2/M1= 0.68 ± 0.14; this is very different from the value of 1.13 ± 0.35 quoted in the literature. Using the new lower mass ratio, and constraining the mass of the white dwarf to be within reasonable limits, then leads to a mass for the secondary star that is substantially less than would be expected for its orbital period if it satisfied a main-sequence mass,radius relationship. We find a spectral type of M0 that is consistent with that expected for a main-sequence star of the low mass we have found. However, in order to fill its Roche lobe, the secondary must be significantly larger than a main-sequence star of that mass and spectral type. The secondary is definitely not a normal main-sequence star. [source] New pulsating white dwarfs in cataclysmic variables,MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2006R. Nilsson ABSTRACT The number of discovered non-radially pulsating white dwarfs (WDs) in cataclysmic variables (CVs) is increasing rapidly by the aid of the Sloan Digital Sky Survey (SDSS). We performed photometric observations of two additional objects, SDSS J133941.11+484727.5 (SDSS 1339), independently discovered as a pulsator by Gänsicke et al., and SDSS J151413.72+454911.9, which we identified as a CV/ZZ Ceti hybrid. In this Letter we present the results of the remote observations of these targets performed with the Nordic Optical Telescope (NOT) during the Nordic,Baltic Research School at Mol,tai Observatory, and follow-up observations executed by NOT in service mode. We also present three candidates we found to be non-pulsating. The results of our observations show that the main pulsation frequencies agree with those found in previous CV/ZZ Ceti hybrids, but specifically for SDSS 1339 the principal period differs slightly between individual observations and also from the recent independent observation by Gänsicke et al. Analysis of SDSS colour data for the small sample of pulsating and non-pulsating CV/ZZ Ceti hybrids found so far seems to indicate that the r,i colour could be a good marker for the instability strip of this class of pulsating WDs. [source] Photometric and spectroscopic observations of three rapidly rotating late-type stars: EY Dra, V374 Peg, and GSC 02038-00293,ASTRONOMISCHE NACHRICHTEN, Issue 8 2010H. Korhonen Abstract Here, BV (RI)C broad band photometry and intermediate resolution spectroscopy in H, region are presented for two rapidly rotating late-type stars: EY Dra and V374 Peg. For a third rapid rotator, GSC 02038-00293, intermediate resolution H, spectroscopy and low resolution spectroscopy are used for spectral classification and stellar parameter investigation of this poorly known object. The low resolution spectrum of GSC 02038-00293 clearly indicates that it is a K-type star. Its intermediate resolution spectrum can be best fitted with a model with Teff = 4750 K and v sin i = 90 km s,1, indicating a very rapidly rotating mid-K star. The H, line strength is variable, indicating changing chromospheric emission on GSC 02038-00293. In the case of EY Dra and V374 Peg, the stellar activity in the photosphere is investigated from the photometric observations, and in the chromosphere from the H, line. The enhanced chromospheric emission in EY Dra correlates well with the location of the photospheric active regions, indicating that these features are spatially collocated. Hints of this behaviour are also seen in V374 Peg, but it cannot be confirmed from the current data. The photospheric activity patterns in EY Dra are stable during one observing run lasting several nights, whereas in V374 Peg large night-tonight variations are seen. Two large flares, one in the H, observations and one from the broadband photometry, and twelve smaller ones were detected in V374 Peg during the observations spanning nine nights. The energy of the photometrically detected largest flare is estimated to be 4.25 × 1031, 4.3 × 1032 erg, depending on the waveband. Comparing the activity patterns in these two stars, which are just below and above the mass limit of full convection, is crucial for understanding dynamo operation in stars with different internal structures (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] New classification and basic stellar parameters of SU EquuleiASTRONOMISCHE NACHRICHTEN, Issue 7 2009O. Behre Abstract The variable star SU Equulei was classified as a close binary with an eclipse light curve previously categorized as WUMa type. The aim of this paper is a review of this old classification on the basis of new observations and a new determination of variable star ephemeris as well as the determination of SU Equ spectral type and distance. New photometric observations in different colours allow a precise determination of the period of variability and yield more accurate light curves allowing a re-classification of the type of variability. We find the best period of variability to be half the old value. The shape of the light curve is inconsistent with an eclipse curve but consistent with an RR Lyrae type c classification. From the B, V, and R colours we deduce a new spectral classification. SU Equulei is an RRc Lyrae type variable of spectral class A8 at a distance of ,12.4 kpc instead of a late-type eclipsing binary (© 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] Recent observations of AB Dor and interpretationASTRONOMISCHE NACHRICHTEN, Issue 4 2009E. Budding Abstract We use minimal empirical modelling techniques to interpret recent (2006,2007) photometry and spectroscopy of AB Dor. We compare, in particular, broadband (B and V) maculation effects with emission features in high-resolution Ca II K-line spectroscopy. We also compare emission effects in the Ca II Kand H, lines observed at different rotational phases. We refer to a broader multiwavelength campaign, of which these optical data were a part, involving X-ray and microwave observations to be published later. The broadband light curves are characterized by one outstanding macula, whereas the emission lines suggest 4 possible main chromospheric activity sites (,faculae'). These appear at a similar latitude and with comparable size to the main umbra, but there are significant displacements in longitude. However, one strong facular concentration near phase zero may have a physical relationship to the main macula. The derived longitudes of these features would have been affected by differential rotation operating over the several months between the spectroscopic and photometric observations, but the difference of at least ,30° between facula and umbra appears too great to allow their coincidence. The possibility of a large bipolar surface structure is considered, keeping in mind the bipolar character of solar activity centres: the activity of rapidly rotating cool stars being generally compared with that of the Sun, scaled up by a few orders of magnitude. Observed microwave activity may link to this same main photospheric and chromospheric centre picked up by the optical analysis. Characterization of macular and facular contributions in stellar activity sites would be improved with a closer timing of observations and higher signal to noise ratios in emission line data (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photospheric and chromospheric activity on EY Dra,ASTRONOMISCHE NACHRICHTEN, Issue 9 2007H. Korhonen Abstract Magnetic activity in the photosphere and chromosphere of the M dwarf EY Dra is studied and possible correlations between the two are investigated using photometric observations in the V and R bands and optical and near infrared spectroscopy. The longitudinal spot configuration in the photosphere is obtained from the V band photometry, and the chromospheric structures are investigated using variations in the H, line profile and observations of the Paschen , line. The shape of the V band light-curve indicates two active regions on the stellar surface, about 0.4 in phase apart. The spectroscopic observations show enhanced H, emission observed close to the phases of the photometrically detected starspots. This could indicate chromospheric plages associated with the photospheric starspots. Some indications of prominence structures are also seen. The chromospheric pressure is limited to log mTR < ,4 based on the non-detection of emission in the Paschen , wavelength region. (© 2007 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] The Blazhko behavior of RV UMaASTRONOMISCHE NACHRICHTEN, Issue 8 2007Zs. Hurta Abstract RV UMa is one of the most extensively studied RR Lyrae stars showing Blazhko modulation. Its photometric observations cover more than 90 years. The published photoelectric observations of RV UMa obtained at the Konkoly Observatory (Kanyó 1976) were re-considered and completed with previously unpublished data. During the time interval of the observations the periods of both the pulsation and the modulation varied within the ranges of 0.000007 and 0.9 days, respectively. We have found a definite but not strict inverse relation between the pulsation and modulation periods of RV UMa. (© 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] | ||||||||||