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Jia-Jia He Sheng-Bang Qian Boonrucksar Soonthornthum Amornrat Aungwerojwit Niang-Ping Liu Thawicharat Sarotsakulchai 《天文和天体物理学研究(英文版)》2019,(4)
Four-color charge-coupled device(CCD) light curves in the B, V, Rc and I c bands of the totaleclipsing binary system V1853 Orionis(V1853 Ori) are presented. By comparing our light curves with those published by previous investigators, it is determined that the O'Connell effect on the light curves has disappeared. By analyzing those multi-color light curves with the Wilson-Devinney code(W-D code),it is discovered that V1853 Ori is an A-type intermediate-contact binary with a degree of contact factor of f = 33.3%(3.7%) and a mass ratio of q = 0.1896(0.0013). Combining our 10 newly determined times of light minima together with others published in the literature, the period changes of the system are investigated. We found that the general trend of the observed minus calculated(O-C) curve shows a downward parabolic variation that corresponds to a long-term decrease in the orbital period with a rate of d P/dt =-1.96(0.46)×10~(-7) d yr~(-1). The long-term period decrease could be explained by mass transfer from the more-massive component to the less-massive one. By combining our photometric solutions with data from Gaia DR_2, absolute parameters were derived as M_1 = 1.20 M⊙, M_2 = 0.23 M⊙, R_1 = 1.36 R⊙and R_2 = 0.66 R⊙. The long-term period decrease and intermediate-contact configuration suggest that V1853 Ori will evolve into a high fill-out overcontact binary. 相似文献
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P. Rodríguez-Gil B. T. Gänsicke H.-J. Hagen S. Araujo-Betancor A. Aungwerojwit C. Allende Prieto D. Boyd J. Casares D. Engels O. Giannakis E. T. Harlaftis J. Kube H. Lehto I. G. Martínez-Pais R. Schwarz W. Skidmore A. Staude M. A. P. Torres 《Monthly notices of the Royal Astronomical Society》2007,377(4):1747-1762
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N. R. Deacon P. J. Groot J. E. Drew R. Greimel N. C. Hambly M. J. Irwin A. Aungwerojwit J. Drake D. Steeghs 《Monthly notices of the Royal Astronomical Society》2009,397(3):1685-1694
We present millimetre observations of a sample of 12 high-redshift ultraluminous infrared galaxies (ULIRGs) in the extended growth strip (EGS). These objects were initially selected on the basis of their observed mid-IR colours ( 0.0 < [3.6]−[4.5] < 0.4 and −0.7 < [3.6]−[8.0] < 0.5 ) to lie at high redshift 1.5 ≲ z ≲ 3 , and subsequent 20–38 μm mid-IR spectroscopy confirms that they lie in a narrow redshift window centred on z ≈ 2 . We detect 9/12 of the objects in our sample at high significance (>3σ) with a mean 1200 μm flux of 〈 F 1200 μm 〉= 1.6 ± 0.1 mJy. Our millimetre photometry, combined with existing far-IR photometry from the Far-IR Deep Extragalactic Legacy Survey (FIDELS) and accurate spectroscopic redshifts, places constraints both sides of the thermal dust peak. This allows us to estimate the dust properties, including the far-IR luminosity, dust temperature and dust mass. We find that our sample is similar to other high- z and intermediate- z ULIRGs, and local systems, but has a different dust selection function than submillimeter-selected galaxies. Finally, we use existing 20-cm radio continuum imaging to test the far-IR/radio correlation at high redshift. We find that our sample is consistent with the local relation, implying little evolution. Furthermore, this suggests that our sample selection method is efficient at identifying ultraluminous, starburst-dominated systems within a very narrow redshift range centred at z ∼ 2 . 相似文献
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Amornrat Luangthip Naphaphat Wilalak Thanittha Thongprapha Kittitep Fuenkajorn 《Arabian Journal of Geosciences》2017,10(6):149
Mechanical characterization tests are performed to determine the effects of carnallite contents on the strength, elasticity, and time-dependent parameters of rock salt specimens obtained from the Lower Member of the Maha Sarakham formation. The specimens are prepared with carnallite content (C %) varying from 0% (pure halite) to 100% (pure carnallite). The compressive and tensile strengths and elastic moduli of the specimens exponentially decrease with increasing C %. Specimens with higher C % tend to dilate more than those with lower C %, as evidenced by the increasing of the Poisson’s ratio. The strength reduction due to the carnallite content decreases as the confining pressures increase. The elastic, visco-elastic, and visco-plastic parameters of the creep test specimens are defined as a function of C %. They rapidly decrease with increasing C %. Pure halite tends to behave as the Burgers material while pure carnallite behaves as the Maxwell material. The different creep rates and deformation mechanisms between halite and carnallite explain the occurrences and structures of potash ore deposit at the shelves and flanks of the salt domes and anticlines in the salt basin. 相似文献
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A. R. Witham C. Knigge B. T. Gänsicke A. Aungwerojwit R. L. M. Corradi J. E. Drew R. Greimel P. J. Groot L. Morales-Rueda E. R. Rodriguez-Flores P. Rodriguez-Gil D. Steeghs 《Monthly notices of the Royal Astronomical Society》2006,369(2):581-597
We report on the properties of 71 known cataclysmic variables (CVs) in photometric Hα emission-line surveys. Our study is motivated by the fact that the Isaac Newton Telescope (INT) Photometric Hα Survey of the northern galactic plane (IPHAS) will soon provide r ', i ' and narrow-band Hα measurements down to r '≃ 20 for all northern objects between − 5° < b < +5° . IPHAS thus provides a unique resource, both for studying the emission-line properties of known CVs and for constructing a new CV sample selected solely on the basis of Hα excess. Our goal here is to carry out the first task and prepare the way for the second. In order to achieve this, we analyse data on 19 CVs already contained in the IPHAS data base and supplement this with identical observations of 52 CVs outside the galactic plane.
Our key results are as follows: (i) the recovery rate of known CVs as Hα emitters in a survey like IPHAS is ≃70 per cent; (ii) of the ≃30 per cent of CVs which were not recovered ≃75 per cent were clearly detected but did not exhibit a significant Hα excess at the time of our observations; (iii) the recovery rate depends only weakly on CV type; (iv) the recovery rate depends only weakly on orbital period; (v) short-period dwarf novae tend to have the strongest Hα lines. These results imply that photometric emission-line searches provide an efficient way of constructing CV samples that are not biased against detection of intrinsically faint, short-period systems. 相似文献
Our key results are as follows: (i) the recovery rate of known CVs as Hα emitters in a survey like IPHAS is ≃70 per cent; (ii) of the ≃30 per cent of CVs which were not recovered ≃75 per cent were clearly detected but did not exhibit a significant Hα excess at the time of our observations; (iii) the recovery rate depends only weakly on CV type; (iv) the recovery rate depends only weakly on orbital period; (v) short-period dwarf novae tend to have the strongest Hα lines. These results imply that photometric emission-line searches provide an efficient way of constructing CV samples that are not biased against detection of intrinsically faint, short-period systems. 相似文献
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John Southworth B. T. Gänsicke T. R. Marsh D. de Martino A. Aungwerojwit 《Monthly notices of the Royal Astronomical Society》2007,378(2):635-640
Intermediate polars (IPs) are cataclysmic variables which contain magnetic white dwarfs with a rotational period shorter than the binary orbital period. Evolutionary theory predicts that IPs with long orbital periods evolve through the 2–3 h period gap, but it is very uncertain what the properties of the resulting objects are. Whilst a relatively large number of long-period IPs are known, very few of these have short orbital periods. We present phase-resolved spectroscopy and photometry of SDSS J233325.92+152222.1 (SDSS J2333) and classify it as the IP with the shortest-known orbital period (83.12 ± 0.09 min), which contains a white dwarf with a relatively long spin period (41.66 ± 0.13 min). We estimate the white dwarf's magnetic moment to be μWD ≈ 2 × 1033 G cm3 , which is not only similar to three of the other four confirmed short-period IPs but also to those of many of the long-period IPs. We suggest that long-period IPs conserve their magnetic moment as they evolve towards shorter orbital periods. Therefore, the dominant population of long-period IPs, which have white dwarf spin periods roughly 10 times shorter than their orbital periods, will likely end up as short-period IPs like SDSS J2333, with spin periods a large fraction of their orbital periods. 相似文献
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SDSS unveils a population of intrinsically faint cataclysmic variables at the minimum orbital period
B. T. Gänsicke M. Dillon J. Southworth J. R. Thorstensen P. Rodríguez-Gil A. Aungwerojwit T. R. Marsh P. Szkody S. C. C. Barros J. Casares D. de Martino P. J. Groot P. Hakala U. Kolb S. P. Littlefair I. G. Martínez-Pais G. Nelemans M. R. Schreiber 《Monthly notices of the Royal Astronomical Society》2009,397(4):2170-2188
We discuss the properties of 137 cataclysmic variables (CVs) which are included in the Sloan Digital Sky Survey (SDSS) spectroscopic data base, and for which accurate orbital periods have been measured. 92 of these systems are new discoveries from SDSS and were followed-up in more detail over the past few years. 45 systems were previously identified as CVs because of the detection of optical outbursts and/or X-ray emission, and subsequently re-identified from the SDSS spectroscopy. The period distribution of the SDSS CVs differs dramatically from that of all the previously known CVs, in particular it contains a significant accumulation of systems in the orbital period range 80–86 min. We identify this feature as the elusive 'period minimum spike' predicted by CV population models, which resolves a long-standing discrepancy between compact binary evolution theory and observations. We show that this spike is almost entirely due to the large number of CVs with very low accretion activity identified by SDSS. The optical spectra of these systems are dominated by emission from the white dwarf photosphere, and display little or no spectroscopic signature from the donor stars, suggesting very low mass companion stars. We determine the average absolute magnitude of these low-luminosity CVs at the period minimum to be 〈 Mg 〉= 11.6 ± 0.7 . Comparison of the SDSS CV sample to the CVs found in the Hamburg Quasar Survey and the Palomar Green Survey suggests that the depth of SDSS is the key ingredient resulting in the discovery of a large number of intrinsically faint short-period systems. 相似文献