- ID:
- ivo://CDS.VizieR/J/PAZh/25/893
- Title:
- Optical outbursts of the blazar 3C 345
- Short Name:
- J/PAZh/25/893
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photographic UBV photometry of the blazar 3C 345 that were made during 79 nights in 1971-1974 and 1983-1984 as a part of the Petersburg Quasar Monitoring Program (PQMP) carried out at the Astronomical Institute of the St.-Petersburg University. These data were previously published by piecemeal (references are presented in Section 4). Now after partial revision these data are united in Table 1 that presents nightly averaged UBV magnitudes together with its rms errors (see Section 4 of the paper for the details). These data were used for the comparison of the spectral indices of the emission in the "fast" (time scales of nearly 10-20 days) and "slow" (time scales of nearly 1 yeas) outbursts in 3C 345.
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- ID:
- ivo://CDS.VizieR/J/AJ/155/90
- Title:
- 1996-2009 optical photometric monitoring for 3C 66A
- Short Name:
- J/AJ/155/90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 3C 66A is one of the most interesting blazars and one of our monitoring objects carried out with the 1.56 m telescope at Sheshan station, Shanghai Astronomical Observatory (ShAO). It has been monitored since 1996 December 11. In the present work, we show its optical light curves during the period of 1996 December 11-2009 December 28. From our observations, we found that the largest variations in the V, R, and I bands are {Delta}V=1.840+/-0.065, {Delta}R=1.898+/-0.069 mag, and {Delta}I=1.659+/-0.047 mag, respectively. Intra-day variabilities are found in the three bands: in the V band, an A=17.7% brightness increase over {Delta}T=47.5 minutes on JD 2455119, and an A=46.27% brightness increase over {Delta}T=271.4 minutes on JD 2454816; in the R band, an A=47.09% brightness increase over {Delta}T=23.18 minutes on JD 2454004, and an A=38.11% brightness increase over {Delta}T=87.98 minutes on JD 2453995; and in the I band, an A=13.2% brightness decrease over {Delta}T=38.44 minutes on JD 2453995, and an A=92.8% brightness decrease over {Delta}T=344.02 minutes on JD 2454818. For micro-variability, we found that R variability leads I variability by 25.92+/-1.09 minutes. When the periodicity analysis methods, with the red noise being considered, are adopted to the V, R, and I observations, we can find that the periodogram to the V data is consistent with red noise, except for 1 CLEANest peak corresponding to the timescale of 696.0+/-182.0 days, those to the R data are 653.0+/-171.0 and 156.0+/-17.0 days; and those to the I data are 801.0+/-207.0 and 156.0+/-15.0 days, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/769/108
- Title:
- Optical photometry of 4 millisecond pulsars
- Short Name:
- J/ApJ/769/108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the last few years, over 43 millisecond radio pulsars have been discovered by targeted searches of unidentified {gamma}-ray sources found by the Fermi Gamma-Ray Space Telescope. A large fraction of these millisecond pulsars are in compact binaries with low-mass companions. These systems often show eclipses of the pulsar signal and are commonly known as black widows and redbacks because the pulsar is gradually destroying its companion. In this paper, we report on the optical discovery of four strongly irradiated millisecond pulsar companions. All four sources show modulations of their color and luminosity at the known orbital periods from radio timing. Light curve modeling of our exploratory data shows that the equilibrium temperature reached on the companion's dayside with respect to their nightside is consistent with about 10%-30% of the available spin-down energy from the pulsar being reprocessed to increase the companion's dayside temperature. This value compares well with the range observed in other irradiated pulsar binaries and offers insights about the energetics of the pulsar wind and the production of {gamma}-ray emission. In addition, this provides a simple way of estimating the brightness of irradiated pulsar companions given the pulsar spin-down luminosity. Our analysis also suggests that two of the four new irradiated pulsar companions are only partially filling their Roche lobe. Some of these sources are relatively bright and represent good targets for spectroscopic follow-up.
- ID:
- ivo://CDS.VizieR/J/MNRAS/447/1661
- Title:
- Optical photometry of nova V5588 Sgr
- Short Name:
- J/MNRAS/447/1661
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The outburst of Nova Sgr 2011 N.2 (=V5588 Sgr) was followed with optical and near-IR photometric and spectroscopic observations for 3.5 yr, beginning shortly before the maximum. V5588 Sgr is located close to Galactic Centre, suffering from E(B-V)=1.56(+/-0.1) extinction. The primary maximum was reached at V=12.37 on UT 2011 April 2.5(+/-0.2), and the underlying smooth decline was moderately fast with t^V^_2_=38 and t^V^_3_=77 d. On top of an otherwise normal decline, six self-similar, fast evolving and bright secondary maxima (SdM) appeared in succession. Only very few other novae have presented so clear SdM. Both the primary maximum and all SdM occurred at later times with increasing wavelengths, by amounts in agreement with expectations from fireball expansions. The radiative energy released during SdM declined following an exponential pattern, while the breadth of individual SdM and the time interval between them widened. Emission lines remained sharp (FWHM~1000 km/s) throughout the whole nova evolution, with the exception of a broad pedestal with a trapezoidal shape ({Delta}vel=3600 km/s at the top and 4500 km/s at the bottom) which was only seen during the advanced decline from SdM maxima and was absent in between SdM. V5588 Sgr at maximum light displayed a typical FeII-class spectrum which did not evolve into a nebular stage. About 10 d into the decline from primary maximum, a typical high-ionization He/N-class spectrum appeared and remained visible simultaneously with the FeII-class spectrum, qualifying V5588 Sgr as a rare hybrid nova. While the FeII-class spectrum faded into oblivion, the He/N-class spectrum developed strong [FeX] coronal lines.
- ID:
- ivo://CDS.VizieR/J/ApJS/183/261
- Title:
- Optical photometry of the ONC
- Short Name:
- J/ApJS/183/261
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present U, B, V, I broadband, 6200{AA} TiO medium band, and H{alpha} narrow band photometry of the Orion Nebula Cluster (ONC) obtained with the WFI imager at the ESO/MPI 2.2 telescope at La Silla Observatory. The nearly simultaneous observations cover the entire ONC in a field of about 34x34arcmin^2^. They enable us to determine stellar colors avoiding the additional scatter in the photometry induced by stellar variability typical of pre-main-sequence stars. We identify 2612 point-like sources in the I band; 58%, 43%, and 17% of them are also detected in V, B, and U, respectively. 1040 sources are identified in the H{alpha} band. In this paper we present the observations, the calibration techniques adopted, and the resulting catalog. We show the derived color-magnitude diagram of the population and discuss the completeness of our photometry. We define a spectrophotometric TiO index that takes into account the fluxes in the V, I, and TiO bands. Comparing it with spectral types of ONC members in the literature, we find a correlation between the index and the spectral type valid for M-type stars, which is accurate to better than 1 spectral subclass for M3-M6 types and better than 2 spectral subclasses for M0-M2 types. This allows us to newly classify 217 stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/882/30
- Title:
- Optical photometry of type Ia SN 2014J
- Short Name:
- J/ApJ/882/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present extensive ground-based and Hubble Space Telescope (HST) photometry of the highly reddened, very nearby SN Ia 2014J in M82, covering the phases from 9 days before to about 900 days after the B-band maximum. SN 2014J is similar to other normal SNe Ia near the maximum light, but it shows flux excess in the B band in the early nebular phase. This excess flux emission can be due to light scattering by some structures of circumstellar materials located at a few 10^17^cm, consistent with a single-degenerate progenitor system or a double-degenerate progenitor system with mass outflows in the final evolution or magnetically driven winds around the binary system. At t~+300 to ~+500 days past the B-band maximum, the light curve of SN 2014J shows a faster decline relative to the 56Ni decay. That feature can be attributed to the significant weakening of the emission features around [FeIII]{lambda}4700 and [FeII]{lambda}5200 rather than the positron escape, as previously suggested. Analysis of the HST images taken at t>600 days confirms that the luminosity of SN 2014J maintains a flat evolution at the very late phase. Fitting the late-time pseudobolometric light curve with radioactive decay of ^56^Ni, ^57^Ni, and ^55^Fe isotopes, we obtain the mass ratio ^57^Ni/^56^Ni as 0.035+/-0.011, which is consistent with the corresponding value predicted from the 2D and 3D delayed-detonation models. Combined with early-time analysis, we propose that delayed-detonation through the single-degenerate scenario is most likely favored for SN 2014J.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/94
- Title:
- Optical polarimetric catalog of stars in the SMC
- Short Name:
- J/ApJ/806/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new optical polarimetric catalog for the Small Magellanic Cloud (SMC). It contains a total of 7207 stars, located in the northeast (NE) and Wing sections of the SMC and part of the Magellanic Bridge. This new catalog is a significant improvement compared to previous polarimetric catalogs for the SMC. We used it to study the sky-projected interstellar magnetic field structure of the SMC. Three trends were observed for the ordered magnetic field direction at position angles (PAs) of (65{deg}+/-10{deg}), (115{deg}+/-10{deg}), and (150{deg}+/-10{deg}). Our results suggest the existence of an ordered magnetic field aligned with the Magellanic Bridge direction and SMC's Bar in the NE region, which have PAs roughly at 115.4{deg} and 45{deg}, respectively. However, the overall magnetic field structure is fairly complex. The trends at 115{deg} and 150{deg} may be correlated with the SMC's bimodal structure, observed in Cepheids' distances and HI velocities. We derived a value of B_sky_=(0.497+/-0.079){mu}G for the ordered sky-projected magnetic field, and {delta}B=(1.465+/-0.069){mu}G for the turbulent magnetic field. This estimate of B_sky_ is significantly larger (by a factor of ~10) than the line of sight field derived from Faraday rotation observations, suggesting that most of the ordered field component is on the plane of the sky. A turbulent magnetic field stronger than the ordered field agrees with observed estimates for other irregular and spiral galaxies. For the SMC the B_sky_/{delta}B ratio is closer to what is observed for our Galaxy than other irregular dwarf galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/402/2087
- Title:
- Optical polarization of OJ 287 in 2005-2009
- Short Name:
- J/MNRAS/402/2087
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- OJ287 is a BL Lac object at redshift z=0.306 that has shown double-peaked bursts at regular intervals of ~12yr during the last ~40yr. We analyse optical photopolarimetric monitoring data from 2005-2009, during which the latest double-peaked outburst occurred. The aim of this study is twofold: firstly, we aim to analyse variability patterns and statistical properties of the optical polarization light-curve. We find a strong preferred position angle in optical polarization. The preferred position angle can be explained by separating the jet emission into two components: an optical polarization core and chaotic jet emission. The optical polarization core is stable on time scales of years and can be explained as emission from an underlying quiescent jet component. The chaotic jet emission sometimes exhibits a circular movement in the Stokes plane. We find six such events, all on the timescales of 10-20days. We interpret these events as a shock front moving forwards and backwards in the jet, swiping through a helical magnetic field. Secondly, we use our data to assess different binary black hole models proposed to explain the regularly appearing double-peaked bursts in OJ287. We compose a list of requirements a model has to fulfil to explain the mysterious behaviour observed in OJ287. The list includes not only characteristics of the light-curve but also other properties of OJ287, such as the black hole mass and restrictions on accretion flow properties. We rate all existing models using this list and conclude that none of the models is able to explain all observations. We discuss possible new explanations and propose a new approach to understanding OJ287. We suggest that both the double-peaked bursts and the evolution of the optical polarization position angle could be explained as a sign of resonant accretion of magnetic field lines, a 'magnetic breathing' of the disc.
- ID:
- ivo://CDS.VizieR/J/ApJS/230/3
- Title:
- Optical & Spitzer photometry in IC 1805
- Short Name:
- J/ApJS/230/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep wide-field optical CCD photometry and mid-infrared Spitzer/IRAC and MIPS 24{mu}m data for about 100000 stars in the young open cluster IC 1805. The members of IC 1805 were selected from their location in the various color-color and color-magnitude diagrams, and the presence of H{alpha} emission, mid-infrared excess emission, and X-ray emission. The reddening law toward IC 1805 is nearly normal (R_V_=3.05+/-0.06). However, the distance modulus of the cluster is estimated to be 11.9+/-0.2mag (d=2.4+/-0.2kpc) from the reddening-free color-magnitude diagrams, which is larger than the distance to the nearby massive star-forming region W3(OH) measured from the radio VLBA astrometry. We also determined the age of IC 1805 ({tau}_MSTO_=3.5Myr). In addition, we critically compared the age and mass scale from two pre-main-sequence evolution models. The initial mass function with a Salpeter-type slope of {Gamma}=-1.3+/-0.2 was obtained and the total mass of IC 1805 was estimated to be about 2700+/-200M_{sun}_. Finally, we found our distance determination to be statistically consistent with the Tycho-Gaia Astrometric Solution Data Release 1, within the errors. The proper motion of the B-type stars shows an elongated distribution along the Galactic plane, which could be explained by some of the B-type stars being formed in small clouds dispersed by previous episodes of star formation or supernova explosions.
- ID:
- ivo://CDS.VizieR/J/ApJ/537/101
- Title:
- Optical Study for blazars. I.
- Short Name:
- J/ApJ/537/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric observations of AGNs are important to construct light curves and to study variability behavior over different timescales. In this paper, the historical optical data compiled from the published literature are presented in tabular form as an optical database for 28 radio-selected BL Lacertae objects. Maximum optical variations are found and compared with the infrared ones. The faintest, brightest, and averaged magnitudes are presented for individual object. The variation is found correlated with polarization. The light curves are shown in figures along with the relation between color index and magnitude. For the color-magnitude relation, two objects, 0735+178 and 0537-441, show evidence that the color index increases with magnitude, indicating that the spectrum flattens when the source brightens, while three objects (0219+428, 1514-241, 2200+420) show the opposite behavior; an object, 0235+164, shows a brightness-dependent color index- magnitude correlation, while the rest of the objects do not show any clear tendency.
