The Faint Optical Counterparts Catalog at 19.4 < r < 22 mag from Herschel-ATLAS SDP FieldZhao, Pin-Song; Zhu, Yi-Nan; Lam, Man I; Wu, Hong; Zhou, Zhi-Min
doi: 10.1088/1538-3873/abb766pmid: N/A
We carry out a spectroscopic survey with Hectospec mounted on the 6.5 m Multiple Mirror Telescope to obtain redshifts of optical counterparts of the Herschel-ATLAS sources in the science demonstration phase field. Our work concerns counterparts with a magnitude range at mag. The observation covers two pointings. In total, we newly obtain redshifts of 158 potential counterparts. Among these counterparts, there are 59 high reliability counterparts. For these high reliability counterparts, we do a SED fitting using MAGPHYS with our spectroscopic redshifts and five Herschel band fluxes, and discover 46 new luminous infra-red galaxies and 10 new ultra luminous infra-red galaxies, including two infra-red QSOs.
Beamed and Unbeamed Emission of γ-Ray BlazarsPei, Zhiyuan; Fan, Junhui; Yang, Jianghe; Bastieri, Denis
doi: 10.1088/1538-3873/abb78fpmid: N/A
A two-component model of radio emission has been used to explain some radio observational properties of Active Galactic Nuclei (AGNs) and, in particular, of blazars. In this work, we extend the two-component idea to the γ-ray emission and assume that the total γ-ray output of blazars consists of relativistically beamed and unbeamed components. The basic idea leverages the correlation between the radio core-dominance parameter and the γ-ray beaming factor. To do so, we evaluate this correlation for a large sample of 584 blazars taken from the fourth source catalog of the Fermi Large Area Telescope (Fermi-LAT) and correlated their γ-ray core-dominance parameters with radio core-dominance parameters. The γ-ray beaming factor is then used to estimate the beamed and unbeamed components. Our analysis confirms that the γ-ray emission in blazars is mainly from the beamed component.
Evidence for Radio Loud to Radio Quiet Evolution from Red and Blue QuasarsGarofalo, David; Bishop, Katie
doi: 10.1088/1538-3873/abb999pmid: N/A
Recent work on red and blue quasi-stellar objects (QSOs) has identified peculiar number distributions as a function of radio-loudness that we explore and attempt to explain from the perspective of a picture in which a subset of the population of active galaxies evolves from the radio-loud to the radio-quiet state. Because the time evolution is slowed down by an order of magnitude or more for the radio-quiet phase, the numbers of red and blue QSOs approach each other at the extreme end of the radio-quiet range of radio-loudness with larger numbers. The rapid time evolution of most radio-loud phases, instead, makes the numbers similar but lower at the far radio-loud end. At the midpoint of radio-loudness, instead, the differences between red and blue QSOs experience their largest values which results from accretion rapidly spinning black holes down but subsequently spinning them up more slowly. Recovering these basic features of the observations is evidence for rapid evolution away from radio-loudness and slow evolution in radio-quiet states.
Extremely Low Mass-ratio Semi-detached Binaries: KIC 2719436 and KIC 4245897Zhang, Jia; Qian, Sheng-Bang; Lyu, Bing
doi: 10.1088/1538-3873/abacd4pmid: N/A
We present two semi-detached binaries with extremely low mass-ratio (<0.1). The total eclipse feature on the light curves greatly improves the reliability of the binary light analysis results. Combining the photometric and spectral data, both the relative and the absolute parameters were obtained based on two methods. The masses and radii are M1 = 1.21 ± 0.45M⊙, M2 = 0.116 ± 0.044M⊙, R1 = 1.89 ± 0.25R⊙, and R2 = 0.76 ± 0.1R⊙ for KIC 2719436, and M1 = 1.58 ± 0.49M⊙, M2 = 0.153 ± 0.051M⊙, R1 = 1.9 ± 0.28R⊙, and R2 = 5.14 ± 0.79R⊙ for KIC 4245897. The binaries with extremely low mass-ratios provide a laboratory to study the binary outcomes as well as the extremely low-mass stars with complete physical properties. KIC 2719436 is an abnormal semi-detached binary system for its primary radius is much larger than that of the evolved secondary star who fills its own Roche Lobe. Excessive mass transfer leads to this situation on account of the effective angular momentum loss probably by the magnetic braking. KIC 2719436 is possible the closest target to the end as a single star that predicted by the TRO theory.
Evryscope-South Survey of Upper- and Pre-main Sequence Solar Neighborhood StarsGalliher, Nathan W.; Ratzloff, Jeffrey K.; Corbett, Hank; Law, Nicholas M.; Howard, Ward S.; Glazier, Amy L.; Soto, Alan Vasquez; Gonzalez, Ramses
doi: 10.1088/1538-3873/abb010pmid: N/A
Using photometric data collected by Evryscope-South, we search for nearby young variable systems on the upper main sequence (UMS) and pre-main sequence (PMS). The Evryscopes are all-sky high-cadence telescope arrays operating in the Northern and Southern hemispheres. We base our search on a Gaia-selected catalog of young neighborhood upper- and pre-main sequence stars which were chosen through both astrometric and photometric criteria. We analyze 44,971 Evryscope-South light curves in search of variability. We recover 615 variables, with 378 previously known, and 237 new discoveries including 84 young eclipsing binaries (EB) candidates. We discover a new highly eccentric binary system and recover a further four previously known systems, with periods ranging from 299 to 674 hr. We find 158 long-period (>50 hr) candidate EB systems, 9 from the PMS and 149 from the UMS, which will allow constraints on the mass/radius/age relation. These long-period EBs include a 179.3 hr PMS system and a 867.8 hr system from the UMS. For PMS variable candidates we estimate system ages, which range from 1 to 23 Myr for non-EBs and from 2 to 17 Myr for EBs. Other non-EB discoveries that show intrinsic variability will allow relationships between stellar rotation rates, ages, activity, and mass to be characterized.
Anomalies and Fluctuations of Near-surface Air Temperature at Tianhuangping (Zhejiang), China, Produced by the Longest Total Solar Eclipse of the 21st Century Under Cloudy SkiesPeñaloza-Murillo, Marcos A.; Roman, Michael T.; Pasachoff, Jay M.
doi: 10.1088/1538-3873/abb2f9pmid: N/A
During a total eclipse of the Sun, the solar disk blocked by the lunar disk produces an instant and strong decline of energy at the surface. This loss of energy leads to a decreasing air temperatures near the surface. Anyone under a completely clear sky, with a total solar eclipse (TSE) in progress, feels a cooling, whose minimum is reached a few minutes after totality. This drop in temperature is known as an anomaly and this delay is called thermal lag. During a TSE air temperature changes appreciably not only in magnitude but also in timing, depending on weather and geographical conditions. If the eclipse is partially or totally obscured by clouds, some effects are produced on the thermal lag. Under clear skies, the temperature response lags behind the change in solar flux as one expects in TSE; however, under cloudy skies, the lag can reverse in early and/or late stages of partial phases. The normal heating of the surface by the Sun, which drives turbulent motion in the air layer near the surface, is disrupted during the eclipse. The 2009 TSE in China provided an opportunity to have a look at these kinds of perturbations caused by this eclipse. In this paper, the second of a series of three, we analyze the near-surface air temperature response, at three different heights over the ground, recorded by the Williams College expedition under meteorological conditions characterized by cloudy skies during the longest total solar eclipse of the 21st century on 2009 July 22, at Tianhuangping (Zhejiang), China. An analysis of the relationship between solar radiation and air temperature was made by applying a study previously published in the first paper of this series in which we evaluated the cloudiness contribution in estimating the impact on global solar radiation throughout this phenomenon at that site. The analysis of this response includes linear and absolute negative anomalies as well as fluctuations, which was undertaken through a statistical study to get information on the convection activity produced by the latter. The fluctuations generated by turbulence were studied by analyzing variance and residuals. The results, indicating a steady decrease and recovery of both perturbations, were consistent with those published by other studies for this total solar eclipse.
Least-squares Spectral and Wavelet Analyses of V455 Andromedae Time Series: The Life After the Super-outburstGhaderpour, Ebrahim; Ghaderpour, Shahnaz
doi: 10.1088/1538-3873/abaf04pmid: N/A
An extensive spectral analysis is performed on the light curve of dwarf nova V455 Andromedae (V455 And = HS 2331+3905) using the Least-squares WAVElet software (LSWAVE) to highlight its robustness for analyzing astronomical time series. The V455 And properties are briefly reviewed, and the recent results are compared with the results obtained herein. It is shown that the new analytical tools are superior to the traditional ones in that they consider observational uncertainties, do not require any interpolation and/or gap-filling, and can estimate the spectral peaks at a higher time–frequency resolution. First, the Anti-leakage Least-squares Spectral Analysis (ALLSSA) is applied to analyze a V455 And unequally spaced time series since 2008. ALLSSA has estimated spectral peaks at 80.40, 40.54, 1.12, and 0.56 minutes that correspond to the orbital period, its first harmonic, the white dwarf spin period, and its harmonic, respectively, confirming the earlier results. ALLSSA is then applied to all sufficiently large-size segments of the light curve to estimate the periodic components and demonstrate the double-humped orbital variations. Next, the Least-squares Wavelet Analysis (LSWA) is applied to four light curve segments each with a sufficient number of observations to study the periodic and aperiodic components. LSWA also detects the spectral peaks corresponding to the orbital period and non-radial white dwarf pulsations at a period of 4–5 minutes in 2010 October which gradually shifts toward 5–6 minutes in 2015 and 2018.