A. Arai, H. Kawakita, A. Raj, Byeong-Cheol Lee, G. Anupama, S. Kondo, Y. Ikeda, N. Kobayashi, S. Hamano, H. Sameshima, K. Fukue, N. Matsunaga, C. Yasui, Natsuko Izumi, M. Mizumoto, S. Otsubo, K. Takenaka, A. Watase, Takafumi Kawanishi, Kenshi Nakanishi, Tetsuya Nakaoka
Two distinct absorption-line systems distinguished by radial velocities have often been observed in the optical high-resolution spectra of classical novae during their early decline phase. The origin of these absorption-line systems is under debates. We present optical high-resolution spectroscopic observations spectra of nova V2659 Cyg and discuss about the temporal evolution of those absorption-line systems observed in this nova during its early decline phase. The observed temporal evolution of absorption-line profiles with relatively higher velocities (the high-velocity component) can be explained qualitatively by the clumpy ejecta and movement of the ionization fronts in the ejecta with time. Conversely, the low-velocity component may originate in the cool region compressed by the shock caused by collision between the fast nova wind and the slow expanding, equatorially focused dense ejecta. We also present high-resolution spectra of V2659 Cyg during its nebular phase in optical and near-infrared wavelength regions. Emission lines detected during the nebular phase also showed two velocity components, suggesting that the velocity structure of the ejecta during the nebular phase is similar to that during the early decline phase. The double-horned profiles of emission lines with low velocities imply a ring-like distribution of materials with lower velocities. The observations during both the early-decline phase and the nebular phase support the multiple ejection of ejecta at a nova explosion, with different velocities.
{"title":"Optical and Near-infrared High-resolution Spectroscopic Observations of Nova V2659 Cyg: Structure of Nova Ejecta and Origin of Two-distinct Velocity Systems","authors":"A. Arai, H. Kawakita, A. Raj, Byeong-Cheol Lee, G. Anupama, S. Kondo, Y. Ikeda, N. Kobayashi, S. Hamano, H. Sameshima, K. Fukue, N. Matsunaga, C. Yasui, Natsuko Izumi, M. Mizumoto, S. Otsubo, K. Takenaka, A. Watase, Takafumi Kawanishi, Kenshi Nakanishi, Tetsuya Nakaoka","doi":"10.22323/1.315.0053","DOIUrl":"https://doi.org/10.22323/1.315.0053","url":null,"abstract":"Two distinct absorption-line systems distinguished by radial velocities have often been observed in the optical high-resolution spectra of classical novae during their early decline phase. The origin of these absorption-line systems is under debates. We present optical high-resolution spectroscopic observations spectra of nova V2659 Cyg and discuss about the temporal evolution of those absorption-line systems observed in this nova during its early decline phase. The observed temporal evolution of absorption-line profiles with relatively higher velocities (the high-velocity component) can be explained qualitatively by the clumpy ejecta and movement of the ionization fronts in the ejecta with time. Conversely, the low-velocity component may originate in the cool region compressed by the shock caused by collision between the fast nova wind and the slow expanding, equatorially focused dense ejecta. We also present high-resolution spectra of V2659 Cyg during its nebular phase in optical and near-infrared wavelength regions. Emission lines detected during the nebular phase also showed two velocity components, suggesting that the velocity structure of the ejecta during the nebular phase is similar to that during the early decline phase. The double-horned profiles of emission lines with low velocities imply a ring-like distribution of materials with lower velocities. The observations during both the early-decline phase and the nebular phase support the multiple ejection of ejecta at a nova explosion, with different velocities.","PeriodicalId":71342,"journal":{"name":"黄金时代","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87107665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nova V2676 Oph is the first classical nova in which C2 has been detected during its early phase near the visual-brightness maximum in addition to CN. The presence of C2 and CN in the nova indicates that its atmosphere was enriched in carbon with C/O > 1. Furthermore, molecule formation in the early phase is likely to be associated with the dust formation that started ∼90 days after the discovery. We have obtained isotopic ratios of carbon and nitrogen for this nova, and they are consistent with model predictions. Based on the lightcurves and optical spectra of the nova, the inferred mass of the white-dwarf component of V2676 Oph is relatively small (∼0.6M⊙). The absence of strong [Ne II] emission at 12.8 μm and the relatively small ejected mass from V2676 Oph support this hypothesis. However, the mass of the white-dwarf component should be higher (>∼1.0M⊙) according to the observed isotopic ratios and theoretical predictions based on thermonuclear runaways.
{"title":"A Review of the Evolution of Classical Nova V2676 Oph: Formation of Molecules and Dust Grains","authors":"H. Kawakita, A. Arai","doi":"10.22323/1.315.0064","DOIUrl":"https://doi.org/10.22323/1.315.0064","url":null,"abstract":"Nova V2676 Oph is the first classical nova in which C2 has been detected during its early phase near the visual-brightness maximum in addition to CN. The presence of C2 and CN in the nova indicates that its atmosphere was enriched in carbon with C/O > 1. Furthermore, molecule formation in the early phase is likely to be associated with the dust formation that started ∼90 days after the discovery. We have obtained isotopic ratios of carbon and nitrogen for this nova, and they are consistent with model predictions. Based on the lightcurves and optical spectra of the nova, the inferred mass of the white-dwarf component of V2676 Oph is relatively small (∼0.6M⊙). The absence of strong [Ne II] emission at 12.8 μm and the relatively small ejected mass from V2676 Oph support this hypothesis. However, the mass of the white-dwarf component should be higher (>∼1.0M⊙) according to the observed isotopic ratios and theoretical predictions based on thermonuclear runaways.","PeriodicalId":71342,"journal":{"name":"黄金时代","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83331363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Pala, A. Ederoclite, N. G. Fusillo, H. V. Ramió, R. Raddi, J. Abril, B. Gänsicke, A. Rebassa-Mansergas
The study of Cataclysmic Variables (CVs) is crucial to test our understanding of binary evolution and its application to many astrophysical phenomena, such as short gamma-ray bursts, X-ray transients and, more important, Supernovae Ia, our yardsticks for measuring distances. Yet, the predicted major component of the present-day CV population, the so-called "period bouncers" (CVs containing a white dwarf and a degenerate donor), has not been detected, highlighting a major discrepancy between theory and observations. We present here CHiCaS, the Compact binary HIgh CAdence Survey, which will perform three hours of uninterrupted time series photometry over 136 square degrees of the sky with JAST/T80Cam. By the end of next year, this program will deliver one minute cadence lightcurves for $simeq 2.5$ million objects as faint as $g simeq 21.5$, along with full colour information. Via detection of their eclipses, CHiCaS will finally, and unambiguously identify the predicted large population of period bouncers. The identification of the missing population will provide an observational support for the current models for the mechanisms of angular momentum loss in compact binaries, which also describe the evolution of all kind of binaries. CHiCaS will also offer a complete and unbiased view into the short term variability of thousands of binaries, eclipsing systems, pulsating stars and CVs in the period gap, which will allow to improve our knowledge of these objects and to carry out additional tests on CV evolution.
{"title":"Testing the models of CV evolution","authors":"A. Pala, A. Ederoclite, N. G. Fusillo, H. V. Ramió, R. Raddi, J. Abril, B. Gänsicke, A. Rebassa-Mansergas","doi":"10.22323/1.315.0042","DOIUrl":"https://doi.org/10.22323/1.315.0042","url":null,"abstract":"The study of Cataclysmic Variables (CVs) is crucial to test our understanding of binary evolution and its application to many astrophysical phenomena, such as short gamma-ray bursts, X-ray transients and, more important, Supernovae Ia, our yardsticks for measuring distances. Yet, the predicted major component of the present-day CV population, the so-called \"period bouncers\" (CVs containing a white dwarf and a degenerate donor), has not been detected, highlighting a major discrepancy between theory and observations. \u0000We present here CHiCaS, the Compact binary HIgh CAdence Survey, which will perform three hours of uninterrupted time series photometry over 136 square degrees of the sky with JAST/T80Cam. By the end of next year, this program will deliver one minute cadence lightcurves for $simeq 2.5$ million objects as faint as $g simeq 21.5$, along with full colour information. Via detection of their eclipses, CHiCaS will finally, and unambiguously identify the predicted large population of period bouncers. The identification of the missing population will provide an observational support for the current models for the mechanisms of angular momentum loss in compact binaries, which also describe the evolution of all kind of binaries. \u0000CHiCaS will also offer a complete and unbiased view into the short term variability of thousands of binaries, eclipsing systems, pulsating stars and CVs in the period gap, which will allow to improve our knowledge of these objects and to carry out additional tests on CV evolution.","PeriodicalId":71342,"journal":{"name":"黄金时代","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86529492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the last two years we assisted to a substantial improvement on the number of CVs discovered, but only few exciting results have been obtained. Thus, in this paper I cannot give astonishing news with respect to those discussed in the review paper published by Giovannelli & Sabau-Graziati (2015a), but simply I will present a personal view about the route to be followed in the investigations on CVs. The exception has been the very exciting news about the discovery of a white dwarf pulsar in AR Sco (Buckley et al., 2017) presented by David Buckley in his talk (Bukley, 2017a, this workshop) and followed by a series of related talks by Beskrovnaya, Meintjes, Isakova, and Ikhsanov (2017, this workshop).
{"title":"The Golden Age of Cataclysmic Variables and Related Objects (A Very Personal Review)","authors":"F. Giovannelli","doi":"10.22323/1.315.0001","DOIUrl":"https://doi.org/10.22323/1.315.0001","url":null,"abstract":"In the last two years we assisted to a substantial improvement on the number of CVs discovered, but only few exciting results have been obtained. \u0000Thus, in this paper I cannot give astonishing news with respect to those discussed in the review paper published by Giovannelli & Sabau-Graziati (2015a), but simply I will present a personal view about the route to be followed in \u0000the investigations on CVs. The exception has been the very exciting news about the discovery of a white dwarf \u0000pulsar in AR Sco (Buckley et al., 2017) presented by David Buckley in his talk (Bukley, 2017a, this workshop) and followed by a series of related talks by Beskrovnaya, Meintjes, Isakova, and Ikhsanov (2017, this workshop).","PeriodicalId":71342,"journal":{"name":"黄金时代","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87284652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The coverage of the pre-maximum stage of novae is sparse, with the exception of a few slow novae where the pre-maximum duration is of the order of some weeks. This paper discusses the main features of novae during the pre-maximum and the maximum stages and reports the preliminary results of an investigation of ASASSN-17hx, a peculiar nova that showed a long pre-maximum and secondary brightenings.
{"title":"Pre-maximum and maximum of Novae: The spectroscopic observations of Nova ASASSN-17hx","authors":"R. Poggiani","doi":"10.22323/1.315.0049","DOIUrl":"https://doi.org/10.22323/1.315.0049","url":null,"abstract":"The coverage of the pre-maximum stage of novae is sparse, with the exception of a few slow novae where the pre-maximum duration is of the order of some weeks. This paper discusses the main features of novae during the pre-maximum and the maximum stages and reports the preliminary results of an investigation of ASASSN-17hx, a peculiar nova that showed a long pre-maximum and secondary brightenings.","PeriodicalId":71342,"journal":{"name":"黄金时代","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82910613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I briefly discuss some personal views developed from the talks and topics covered at this meeting. Specifically, I address a process-oriented theme that focuses on relevant processes independent of scale or source type. For example, magnetism, accretion disk formation, and stellar evolution work in a wide variety of source types, independent of human-made classification schemes. I suggest a process-centered approach where lessons learned about phenomena that are well observed in one source class are sensibly applied elsewhere. Features of one class of accreting binary may appear in another class in a related but distinct way. Several examples that were highlighted in this meeting are discussed.
{"title":"Concluding Remarks; What CVs Can Teach Us About Other Astrophysical Sources","authors":"P. Mason","doi":"10.22323/1.315.0073","DOIUrl":"https://doi.org/10.22323/1.315.0073","url":null,"abstract":"I briefly discuss some personal views developed from the talks and topics covered at this meeting. Specifically, I address a process-oriented theme that focuses on relevant processes independent of scale or source type. For example, magnetism, accretion disk formation, and stellar evolution work in a wide variety of source types, independent of human-made classification schemes. I suggest a process-centered approach where lessons learned about phenomena that are well observed in one source class are sensibly applied elsewhere. Features of one class of accreting binary may appear in another class in a related but distinct way. Several examples that were highlighted in this meeting are discussed.","PeriodicalId":71342,"journal":{"name":"黄金时代","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89569498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yasuyuki Wakamatsu, K. Isogai, T. Morita, Taichi Kato, D. Nogami, M. Uemura, Shiro Ikeda
We have developed a new eclipse mapping method with Total Variation Minimization (TVM). TVM uses a concept of sparse modeling, which recovers information from sparse data. TVM sets a summation of difference in the brightness of adjacent elements in a map to be sparse. We included this concept to the eclipse mapping method and evaluated consistency of the reconstruction of the model disk. The reconstruction of the model light curve seems to be fine but that of the model disk seems to be failed, smearing the brightness distribution along the ingress/egress arcs produced by the shadow of the secondary. We applied our method to the 2017 superoutburst of HT Cas. The artifacts smearing along the ingress/egress arcs of the secondary also exist. Unaccounted noise and the short phase coverage of the input light curves seem to affect the results, leading to small artificial bright spots in the reconstructed disk.
{"title":"New method of eclipse mapping and an application to HT Cas in the 2017 superoutburst","authors":"Yasuyuki Wakamatsu, K. Isogai, T. Morita, Taichi Kato, D. Nogami, M. Uemura, Shiro Ikeda","doi":"10.22323/1.315.0025","DOIUrl":"https://doi.org/10.22323/1.315.0025","url":null,"abstract":"We have developed a new eclipse mapping method with Total Variation Minimization (TVM). \u0000TVM uses a concept of sparse modeling, which recovers information from sparse data. \u0000TVM sets a summation of difference in the brightness of adjacent elements in a map to be sparse. \u0000We included this concept to the eclipse mapping method and evaluated consistency of the reconstruction of the model disk. \u0000The reconstruction of the model light curve seems to be fine but that of the model disk seems to be failed, smearing the brightness distribution along the ingress/egress arcs produced by the shadow of the secondary. \u0000 \u0000We applied our method to the 2017 superoutburst of HT Cas. \u0000The artifacts smearing along the ingress/egress arcs of the secondary also exist. \u0000Unaccounted noise and the short phase coverage of the input light curves seem to affect the results, leading to small artificial bright spots in the reconstructed disk.","PeriodicalId":71342,"journal":{"name":"黄金时代","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84435397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Szegedi, A. Odendaal, P. Meintjes, B. V. Soelen, J. P. Marais, A. Rajoelimanana, M. M. Nyamai, R. Britto, L. Hanlon, D. Murphy, A. Martin-Carrillo, M. Motsoaledi, J. Thorstensen
We present optical photometric and spectroscopic observations of three SU UMa-type dwarf novae, i.e. AR Pic, QW Ser and V521 Peg, conducted in 2016 and 2017. These sources were selected from the Catalina Real-Time Transient Survey and observed during quiescence, outburst (AR Pic and QW Ser) and superoutburst (V521 Peg). For AR Pic, strong flickering in the light curves and an asymmetric double-peaked H$beta$ emission line in the spectra, confirmed the presence of a very active hot spot. During outburst, detected on 18 February 2017, it exhibited a $sim 3.3$ magnitude brightening. The projected velocity of the inner edge of the accretion disc is $sim 2000 rm~km~s^{-1}$. An outburst of QW Ser was detected on 8 August 2016. Absorption lines, characteristic of an optically thick disc during outburst, were detected and an outflow velocity of $sim 1000 rm ~km~s^{-1}$ was determined. Optical spectra during the superoutburst of V521 Peg were obtained for the first time, confirming the superoutburst nature of the outburst, as also observed in other SU UMa-type dwarf novae. The superoutburst was detected on 1 September 2017. Well-defined superhumps were observed, with an average superhump period of $P_{rm sh} sim 1.48$ hr. A mass ratio of $q sim 0.14$ was determined from the period excess of $varepsilon sim 3 %$.
{"title":"Transient emission of selected CRTS Cataclysmic Variables","authors":"H. Szegedi, A. Odendaal, P. Meintjes, B. V. Soelen, J. P. Marais, A. Rajoelimanana, M. M. Nyamai, R. Britto, L. Hanlon, D. Murphy, A. Martin-Carrillo, M. Motsoaledi, J. Thorstensen","doi":"10.22323/1.315.0021","DOIUrl":"https://doi.org/10.22323/1.315.0021","url":null,"abstract":"We present optical photometric and spectroscopic observations of three SU UMa-type dwarf novae, i.e. AR Pic, QW Ser and V521 Peg, conducted in 2016 and 2017. These sources were selected from the Catalina Real-Time Transient Survey and observed during quiescence, outburst (AR Pic and QW Ser) and superoutburst (V521 Peg). For AR Pic, strong flickering in the light curves and an asymmetric double-peaked H$beta$ emission line in the spectra, confirmed the presence of a very active hot spot. During outburst, detected on 18 February 2017, it exhibited a $sim 3.3$ magnitude brightening. The projected velocity of the inner edge of the accretion disc is $sim 2000 rm~km~s^{-1}$. An outburst of QW Ser was detected on 8 August 2016. Absorption lines, characteristic of an optically thick disc during outburst, were detected and an outflow velocity of $sim 1000 rm ~km~s^{-1}$ was determined. Optical spectra during the superoutburst of V521 Peg were obtained for the first time, confirming the superoutburst nature of the outburst, as also observed in other SU UMa-type dwarf novae. The superoutburst was detected on 1 September 2017. Well-defined superhumps were observed, with an average superhump period of $P_{rm sh} sim 1.48$ hr. A mass ratio of $q sim 0.14$ was determined from the period excess of $varepsilon sim 3 %$.","PeriodicalId":71342,"journal":{"name":"黄金时代","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83640495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Schmidtobreick, C. Tappert, M. Shara, S. Scaringi, A. Bayo, N. Vogt, A. Ederoclite
A nova eruption in a cataclysmic variable (CV) is a thermonuclear explosion on the surface of the white-dwarf primary once it has accreted a critical mass from its late-type companion. Between these eruptions, the binary is supposed to appear as a ’normal’ CV, although for the first tens or hundreds of years, the white dwarf is still heated up which might influence the mass-transfer rate of the binary. To compare the nova-populations with the general CV-one, a large number of old novae are needed. We have conducted a program to recover old novae and study the binary within. We here present the results of this program as well as a new deep wide-field Hα + [NII] survey of cataclysmic variables to search for remnant nova shells around these objects. Such shells have been found around some cataclysmic variables that were hitherto not known as novae. They provide the unambiguous evidence that the system has experienced a nova eruption in the past and thus point to the oldest novae observable.
{"title":"The hunt for ancient novae","authors":"L. Schmidtobreick, C. Tappert, M. Shara, S. Scaringi, A. Bayo, N. Vogt, A. Ederoclite","doi":"10.22323/1.315.0046","DOIUrl":"https://doi.org/10.22323/1.315.0046","url":null,"abstract":"A nova eruption in a cataclysmic variable (CV) is a thermonuclear explosion on the surface of the white-dwarf primary once it has accreted a critical mass from its late-type companion. Between these eruptions, the binary is supposed to appear as a ’normal’ CV, although for the first tens or hundreds of years, the white dwarf is still heated up which might influence the mass-transfer rate of the binary. To compare the nova-populations with the general CV-one, a large number of old novae are needed. \u0000We have conducted a program to recover old novae and study the binary within. We here present the results of this program as well as a new deep wide-field Hα + [NII] survey of cataclysmic variables to search for remnant nova shells around these objects. Such shells have been found around some cataclysmic variables that were hitherto not known as novae. They provide the unambiguous evidence that the system has experienced a nova eruption in the past and thus point to the oldest novae observable.","PeriodicalId":71342,"journal":{"name":"黄金时代","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81496458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report on the photometric observation of RZ LMi, which is a dwarf nova renowned for its extremely short ( 19 d) and regular supercycle, in 2013 and 2016. The supercycles observed in both years were longer than previously reported values of 19 d. Especially in 2016, we observed two exceptionally long superoutbursts with drations of 28 d and 48 d, which require very high mass transfer rate, 97 % and 99 % of the critical mass transfer rate, respectively. We consider thatthe object virtually experienced a transition to the nova-like state. We detected growing (stage A)superhumps with a mean period of 0.0602(1) d in 2013 and 2016, and possible negative super-humps with a period of 0.05710(1) d. By using the two periods, we estimated an orbital period of 0.05792 d. The orbital period suggests a mass ratio of 0.10, which is larger than mass ratios in WZ Sge-type dwarf novae with orbital periods similar to RZ LMi, and even above that of some ordinary SU UMa-type dwarf novae with similar orbital periods. The exceptionally high mass-transfer rate in this object may possibly be ecplained by a stripped secondary with an evolved core in a system evolving toward an AM CVn-type object.
{"title":"The bridge between ER Ursae Majoris-type dwarf nova and nova-like system","authors":"R. Ishioka, Taichi Kato","doi":"10.22323/1.315.0063","DOIUrl":"https://doi.org/10.22323/1.315.0063","url":null,"abstract":"We report on the photometric observation of RZ LMi, which is a dwarf nova renowned for its extremely short ( 19 d) and regular supercycle, in 2013 and 2016. The supercycles observed in both years were longer than previously reported values of 19 d. Especially in 2016, we observed two exceptionally long superoutbursts with drations of 28 d and 48 d, which require very high mass transfer rate, 97 % and 99 % of the critical mass transfer rate, respectively. We consider thatthe object virtually experienced a transition to the nova-like state. We detected growing (stage A)superhumps with a mean period of 0.0602(1) d in 2013 and 2016, and possible negative super-humps with a period of 0.05710(1) d. By using the two periods, we estimated an orbital period of 0.05792 d. The orbital period suggests a mass ratio of 0.10, which is larger than mass ratios in WZ Sge-type dwarf novae with orbital periods similar to RZ LMi, and even above that of some ordinary SU UMa-type dwarf novae with similar orbital periods. The exceptionally high mass-transfer rate in this object may possibly be ecplained by a stripped secondary with an evolved core in a system evolving toward an AM CVn-type object.","PeriodicalId":71342,"journal":{"name":"黄金时代","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83253607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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