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- ID:
- ivo://CDS.VizieR/J/A+A/575/L6
- Title:
- Optical observations of LS I +61 303
- Short Name:
- J/A+A/575/L6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The gamma-ray binary LS I +61 303 is composed of a Be star and a compact companion orbiting in an eccentric orbit. Variable flux modulated with the orbital period of ~26.5d has been detected from radio to very high-energy gamma-rays. In addition, the system presents a superorbital variability of the phase and amplitude of the radio outbursts with a period of ~4.6yr. We present optical photometric observations of LS I +61 303 spanning ~1.5yr (table 1) and contemporaneous H-alpha equivalent width (EW) data (table 2). The optical photometry shows, for the first time, that the known orbital modulation suffers a positive orbital phase shift and an increase in flux for data obtained 1-yr apart. The orbital modulation of the EW presents, for the first time, a positive orbital phase shift. These orbital phase shifts of the thermal indicators are in line with the observed behavior for nonthermal indicators, such as X-ray or radio emission. This shows that there is a strong coupling between the thermal and nonthermal emission processes in the gamma-ray binary LS I +61 303.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/118
- Title:
- Optical obs. of GRB 180205A with COATLI
- Short Name:
- J/ApJ/872/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical photometry of the afterglow of the long GRB 180205A with the COATLI telescope from 217s to about 5d after the Swift/BAT trigger. We analyze this photometry in conjunction with the X-ray light curve from Swift/XRT. The late-time light curves and spectra are consistent with the standard forward-shock scenario. However, the early-time optical and X-ray light curves show atypical behavior; the optical light curve exhibits a flat plateau while the X-ray light curve shows a flare. We explore several scenarios and conclude that the most likely explanation for the early behavior is late activity of the central engine.
- 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.
- 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/AJ/160/235
- Title:
- Optical photometry and RVs of TOI-481b and TOI-892b
- Short Name:
- J/AJ/160/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of two new 10 day period giant planets from the Transiting Exoplanet Survey Satellite mission, whose masses were precisely determined using a wide diversity of ground-based facilities. TOI-481b and TOI-892b have similar radii (0.99{+/-}0.01R_Jup_ and 1.07{+/-}0.02R_Jup_, respectively), and orbital periods (10.3311days and 10.6266days, respectively), but significantly different masses (1.53{+/-}0.03M_Jup versus 0.95{+/-}0.07M_Jup_, respectively). Both planets orbit metal-rich stars ([Fe/H]=+0.26{+/-}0.05dex and [Fe/H]=+0.24{+/-}0.05 for TOI-481 and TOI-892, respectively) but at different evolutionary stages. TOI-481 is a M_*_=1.14{+/-}0.02M_{odot}_, R_*_=1.66{+/-}0.02R_{odot}_ G-type star (Teff=5735{+/-}72K), that with an age of 6.7Gyr, is in the turn-off point of the main sequence. TOI-892 on the other hand, is a F-type dwarf star (Teff=6261{+/-}80K), which has a mass of M_*_=1.28{+/-}0.03M_{odot}_ and a radius of R_*_=1.39{+/-}0.02R_{odot}_. TOI-481b and TOI-892b join the scarcely populated region of transiting gas giants with orbital periods longer than 10days, which is important to constrain theories of the formation and structure of hot Jupiters.
- ID:
- ivo://CDS.VizieR/J/AJ/150/67
- Title:
- Optical photometry for 1ES 1959+650
- Short Name:
- J/AJ/150/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the 1.56m telescope at Shanghai Observatory, China, we present the photometric results of 1ES 1959+650, which cover from 2006 June 11 to 2014 July 31. The maximum variabilities are {Delta}m_V|max_=1.74+/-0.02mag in the V band, {Delta}m_R|max_=0.97+/-0.02mag in the R band, and {Delta}m_I/max_=1.15+/-0.03mag in the I band. During the monitoring period, we obtain intraday variabilities on 2009 September 2 (JD2455077) and 2009 September 3 (JD2455078). On 2009 September 2, the intraday variabilities are {Delta}m_V_=0.36+/-0.08mag within 1.56hr, {Delta}m_R_=0.21+/-0.04mag within 23minutes, and {Delta}m_I_=0.53+/-0.03mag within 45minutes. On 2009 September 3, the intraday variabilities are {Delta}m_V_=0.40+/-0.10mag within 27minutes, {Delta}m_R_=0.48+/-0.04mag within 3.24hr, and {Delta}m_I_=0.68+/-0.06mag within 3.72hr. The two intraday variabilities occur in 24hr, which may occur in the same variable phase. Other results show that (1) no quasi-periodicity is found in the long-term light curve and (2) the correlations between the brightness and the spectrum show obvious anti-correlation, {alpha}=-(0.18+/-0.02)F_V_+(2.33+/-0.12), with the correlation coefficient r=-0.74 and the chance probability p<0.01%.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/79
- Title:
- Optical photometry in 3 Local Group dwarf galaxies
- Short Name:
- J/ApJ/756/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep wide-field photometry of three recently discovered faint Milky Way (MW) satellites: Leo V, Pisces II, and Canes Venatici II. Our main goals are to study the structure and star formation history of these dwarfs; we also search for signs of tidal disturbance. The three satellites have similar half-light radii (~60-90pc) but a wide range of ellipticities. Both Leo V and CVn II show hints of stream-like overdensities at large radii. An analysis of the satellite color-magnitude diagrams shows that all three objects are old (>10Gyr) and metal-poor ([Fe/H]~-2), though neither the models nor the data have sufficient precision to assess when the satellites formed with respect to cosmic reionization. The lack of an observed younger stellar population (<~10Gyr) possibly sets them apart from the other satellites at Galactocentric distances >~150kpc. We present a new compilation of structural data for all MW satellite galaxies and use it to compare the properties of classical dwarfs to the ultra-faints. The ellipticity distribution of the two groups is consistent at the ~2{sigma} level. However, the faintest satellites tend to be more aligned toward the Galactic Center, and those satellites with the highest ellipticity (>~0.4) have orientations ({Delta}{theta}_GC_) in the range 20{deg}<~{Delta}{theta}_GC_<~40{deg}. This latter observation is in rough agreement with predictions from simulations of dwarf galaxies that have lost a significant fraction of their dark matter halos and are being tidally stripped.
- 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.
