- ID:
- ivo://CDS.VizieR/J/A+A/417/745
- Title:
- V(RI)C differential photometry of V861 Her
- Short Name:
- J/A+A/417/745
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- First Cousins V(RI)_C_ light curves of the W UMa-type eclipsing variable star V861 Herculis are presented. The system was observed in 2000 and 2003. The light curves obtained at different epochs showed significant deviation from each other. The O'Connell effect (usually explained by spots on the surface which are responsible for variations in the intensity of the system) was about {Delta}V=0.05mag in 2000 but it vanished in 2003 (except the night of February 22/23, 2003 when we observed a small O'Connell effect ({Delta}V=0.020)). Further peculiarities of the light curves are also discussed.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/132/960
- Title:
- V(RI)c light-curves of EQ Tauri
- Short Name:
- J/AJ/132/960
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New V, R_C_, and I_C_ light curves of EQ Tau have been obtained in 2002 and 2003. These show the secondary minimum to be a total eclipse. These new light curves have been analyzed, together with the published radial velocity observations, using the Wilson-Devinney code. The binary has an overcontact configuration, with an orbital inclination of 85{deg}, a difference in component temperature of 80K, and an overcontact fill-out factor of 16%. Absolute parameters of the component stars have been determined: M1=1.28M_{sun}_, R1=1.17R_{sun}_, L1=1.39 L_{sun}_, and M2=0.47M_{sun}_, R2=0.81R_{sun}_, L2=0.63L_{sun}_. The calculated distance is 180+/-20pc. A critical review of our new timings of minimum light together with previously published ones suggests a change from one constant period to another one around 1974 rather than a cyclical variation. When corrected for energy transfer in the common envelope, the physical parameters of the two components are in good agreement with those of unevolved single stars of similar masses.
- ID:
- ivo://CDS.VizieR/J/A+A/343/446
- Title:
- VRI Cousins photometry of Am stars
- Short Name:
- J/A+A/343/446
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tablea1 contains photoelectric VRI Cousins photometry for 63 Am stars observed on the 17th June, 1996 with the 1.52m telescope of the Observatorio Astronomico Nacional (O.A.N.) at Calar Alto (Almeria, Spain), and on the 25th and 26th of the same month using the 1m Jakobus Kapteyn telescope at the Observatorio del Roque de los Muchachos (O.R.M., Canary Islands, Spain). The reduction procedure followed is explained in Rossello et al. (1985A&AS...59..399R) and Landolt (1983, Cat. <II/118>; 1983AJ.....88..853L) standard stars were used. We provide the V magnitude, the (V-R) and (V-I) colour indices, their associated standard errors and the number of observations performed for each star.
- ID:
- ivo://CDS.VizieR/J/AJ/147/9
- Title:
- VRIJHK light curves of V582 Mon
- Short Name:
- J/AJ/147/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multi-wavelength (VRIJHK) observations of KH 15D obtained in 2012/2013, as well as a master table of standard photometry spanning the years 1967 to 2013. The system is a close, eccentric T Tauri binary embedded in an inclined precessing circumbinary (CB) ring. The most recent data show the continued rise of star B with respect to the trailing edge of the occulting horizon as the system's maximum brightness steadily increases. The wealth of data in time and wavelength domains allows us to track the long-term CCD color evolution of KH 15D. We find that the V-I behavior is consistent with direct and scattered light from the composite color of two stars with slightly different temperatures. There is no evidence for any reddening or bluing associated with extinction or scattering by interstellar-medium-size dust grains. Furthermore, we probe the system's faint phase behavior at near-infrared wavelengths in order to investigate extinction properties of the ring and signatures of a possible shepherding planet sometimes invoked to confine the CB ring at ~5AU. The wavelength independence of eclipse depth at second contact is consistent with the ring material being fully opaque to 2.2{mu}m. The color-magnitude diagrams demonstrate excess flux in J and H at low light levels, which may be due to the presence of a hot, young Jupiter-mass planet.
- ID:
- ivo://CDS.VizieR/J/A+A/469/503
- Title:
- VRIJHK observations of PKS 2155-304
- Short Name:
- J/A+A/469/503
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectral variability is the main tool for constraining emission models of BL Lac objects. By means of systematic observations of the BL Lac prototype PKS 2155-304 in the infrared-optical band, we explore variability on the scales of months, days and hours. We made our observations with the robotic 60cm telescope REM located at La Silla, Chile. VRIJHK filters were used. PKS 2155-304 was observed from May to December 2005. The wavelength interval explored, the total number of photometric points and the short integration time render our photometry substantially superior to previous ones for this source. On the basis of the intensity and colour we distinguish three different states of the source, each of duration of months, which include all those described in the literature. In particular, we report the highest state ever detected in the H band. The source varied by a factor of 4 in this band, much more than in the V band (a factor of about 2). The source softened with increasing intensity, contrary to the general pattern observed in the UV-X-ray bands. On five nights of November we had nearly continuous monitoring for 2-3 hours. A variability episode with a time scale of tau approx 24h is well documented, a much more rapid flare with tau=1-2h, is also apparent, but is supported by relatively few points. The overall spectral energy distribution of PKS 2155-304 is commonly described by a synchrotron-self-Compton model. The optical infrared emission is however in excess of the expectation of the model, in its original formulation. This can be explained by a variation of the frequency of the synchrotron peak, which is not unprecedented in BL Lacs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/384/107
- Title:
- VRIJHK photometry of SN 2002cv
- Short Name:
- J/MNRAS/384/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present VRIJHK photometry, and optical and near-infrared spectroscopy, of the heavily extinguished Type Ia supernova (SN Ia) 2002cv, located in NGC 3190, which is also the parent galaxy of the SN Ia 2002bo. SN 2002cv, not visible in the blue, has a total visual extinction of 8.74+/-0.21mag. In spite of this, we were able to obtain the light curves between 10 and +207d from the maximum in the I band, and also to follow the spectral evolution, deriving its key parameters. We found the peak I-band brightness to be I_max_=16.57+/-0.10mag, the maximum absolute I magnitude to be M_max_I=18.79+/-0.20, and the parameter {delta}m15(B) specifying the width of the B-band light curve to be 1.46+/-0.17mag. The latter was derived using the relations between this parameter and {delta}m40(I) and the time-interval {delta}t_max_(I) between the two maxima in the I-band light curve. As has been found for previously observed, highly extinguished SNe Ia, a small value of 1.59+/-0.07 was obtained here for the ratio RV of the total-to-selective extinction ratio for SN 2002cv, which implies a small mean size for the grains along the line of sight towards us. Since it was found for SN 2002bo a canonical value of 3.1, here we present a clear evidence of different dust properties inside NGC 3190.
- ID:
- ivo://CDS.VizieR/J/AJ/155/47
- Title:
- VRIJHK photometry of the T Tauri binary KH 15D
- Short Name:
- J/AJ/155/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present VRIJHK photometry of the KH 15D T Tauri binary system for the 2015/2016 and 2016/2017 observing seasons. For the first time in the modern (CCD) era, we are seeing Star B fully emerge from behind the trailing edge of the precessing circumbinary ring during each apastron passage. We are, therefore, able to measure its luminosity and color. Decades of photometry on the system now allow us to infer the effective temperature, radius, mass, and age of each binary component. We find our values to be in good agreement with previous studies, including archival photographic photometry from the era when both stars were fully visible, and they set the stage for a full model of the system that can be constructed once radial velocity measurements are available. We also present the first high-sensitivity radio observations of the system, taken with the Atacama Large Millimeter/submillimeter Array and the Submillimeter Array. The respective 2.0 and 0.88 mm observations provide an upper limit on the circumbinary (gas and dust) disk mass of 1.7 M_Jup_ and reveal an extended CO outflow, which overlaps with the position, systemic velocity, and orientation of the KH 15D system and is certainly associated with it. The low velocity, tight collimation, and extended nature of the emission suggest that the outflow is inclined nearly orthogonal to the line of sight, implying it is also orthogonal to the circumbinary ring. The position angle of the radio outflow also agrees precisely with the direction of polarization of the optical emission during the faint phase. A small offset between the optical image of the binary and the central line of the CO outflow remains a puzzle and possible clue to the jet launching mechanism.
- ID:
- ivo://CDS.VizieR/J/A+A/468/1039
- Title:
- VRIJK photometry of GQ Lup
- Short Name:
- J/A+A/468/1039
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We wanted to determine the rotation parameters of GQ Lup A, thereby constraining the evolutionary history of the GQ Lup system. We have undertaken a photometric monitoring campaign on GQ Lup A consisting of two epochs spaced one year apart. We also searched the photometric archives to enlarge the data set.
- ID:
- ivo://CDS.VizieR/J/AJ/150/9
- Title:
- VRI light curves of GSC 1537-1557
- Short Name:
- J/AJ/150/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By analyzing R_c_ and I_c_light curves of the short-period solar-type eclipsing binary GSC 1537-1557 we discovered that it is a shallow contact binary with a degree of contact factor of f=(8.1+/-1.79)%. Photometric solutions reveal that GSC 1537-1557 is a W-type system with a mass ratio of q=M_2_/M_1_=2.645 where the less massive component (the primary star) is about 110K hotter than the more massive one (the secondary star). The asymmetry and variation of the light curves were explained as the activity of spots on the solar-type component stars. By investigating all of the available times of light minima, we found that the observed-calculated (O-C) curve shows a cyclic variation with a small amplitude of 0.00335days and a period of 8.1years. The small-amplitude cyclic change in the O -C curve was analyzed for the light-travel time effect via the presence of an extremely cool stellar companion. The mass of the third body was determined to be M_3_sini'=(0.19+/-0.01)M_{sun}_ when M_1_+M_2_=1.31M_{sun}_ is adopted for GSC 1537-1557. The semimajor axis of the outer obit is a'sini'=(4.58+/-0.33)AU.
- ID:
- ivo://CDS.VizieR/J/AJ/115/1801
- Title:
- VRI photometry of M87 globular clusters
- Short Name:
- J/AJ/115/1801
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the high-resolution camera at the Canada-France-Hawaii Telescope to obtain VRI photometry of the globular clusters in the innermost 140 of the M87 halo. The results are used to discuss several issues concerning the formation and evolution of globular cluster systems in supergiant elliptical galaxies like M87. Our principal results are as follows: (1) From our deep R-band photometry of the cluster population, we find no significant change in the globular cluster luminosity function (GCLF) with galactocentric radius, for cluster masses M>=10^5^M_{sun}_. This result places constraints on current theoretical predictions of the rate of cluster evolution by tidal shocking and evaporation, indicating that the main effects of dynamical evolution may be felt only on lower mass clusters (<~10^5^M_{sun}_) that are below the faint limit of most current observations. (2) Combining our V-I color indices with other data in the literature, we derive the metallicity gradient and mean metallicity of the clusters from r=9" out to r~500" (~0.7-35kpc). Within the core radius r_c_=1' of the globular cluster system, the metallicity distribution is uniform, but at larger radii the mean metallicity declines steadily as Z/Z_{sun}_~r^-0.9^. (3) The various options for explaining the existence of high specific frequency galaxies like M87 are evaluated. (4) We offer a new explanation for the large observed S_N_ range among the brightest cluster elliptical galaxies (BCGs). It is suggested that these central supergiant E galaxies formed in an exceptionally turbulent or high-density environment which favored a very rapid initial star formation burst. From a total sample of 30 BCGs, we derive empirical scaling relations that relate to this hypothesis. Our analysis favors the view that BCGs began forming at redshifts z>~5, distinctly earlier than most other galaxies.
