Infrared photometry of the symbiotic novae V1016 Cyg and HM Sge in 1978–1999

The photometric JHKLM observations of the symbiotic novae V1016 Cyg and HM Sge in 1978–1999 are presented. Parameters of the cool stars themselves and the dust envelopes are estimated. The periods of 470±5 days (for V1016 Cyg) and 535±5 days (for HM Sge) are reliably determined from the entire set of our photometric J data for V1016 Cyg and HM Sge. In addition, monotonic light and color variations are observed on a time scale of several thousand days, with the increase in infrared brightness occurring with the simultaneous decrease in infrared color indices; i.e., the dust envelopes in which both components of the systems were embedded before the outburst of their hot sources in 1964 and 1975, respectively, had continued to disperse until late 1999. The amplitudes of these variations for HM Sge are almost twice those for V1016 Cyg. For HM Sge, the dust envelope reached a maximum density near JD 2447500 and then began to disperse. In the case of V1016 Cyg, a maximum density of the dust envelope was probably reached near JD 2444800, and its dispersal has been continuing for about 20 years. Thus, in both symbiotic novae, their dust envelopes reached a maximum density approximately eight years after the outburst of the hot component and then began to disperse. An analysis of the color-magnitude (J–K, J) diagram reveals that grains in the dust envelopes of V1016 Cyg and HM Sge are similar in their optical properties to impure silicates. The observed [J–K, K–L] color variations for the symbiotic novae under study can be explained in terms of the simple model we chose by variations in the Mira's photospheric temperature from 2400 to 3000 K and in the dust-envelope optical depth from 1 to 3 at a wavelength of 1.25 µm for a constant grain temperature. The observed J–K and K–L color indices for both symbiotic novae, while decreasing, tend to the values typical of Miras. The dust envelopes of both symbiotic novae are optically thick. The dust envelope around HM Sge is, on the average, twice as dense as that around V1016 Cyg; the Mira in V1016 Cyg is slightly cooler (~2800–2900 K) than that in HM Sge (~2600–2700 K). The dust-envelope density decreases as the Mira's temperature increases. The absolute bolometric magnitudes are $ - 5\mathop .\limits^m 1 \pm 0\mathop .\limits^m 15$ for V 1016 Cyg and $5\mathop .\limits^m 27 \pm 0\mathop .\limits^m 17$ for HM Sge. Their distances are 2.8±0.6 and 1.8±0.4 kpc, respectively; the luminosities and radii of their cool components (Miras) are 8.6×10³ L _⊙, 1×10⁴ L _⊙, 500R _⊙, and 540R _⊙. The radii of their dust envelopes are 1400R _⊙ and 1500R _⊙; the masses are (3?3.3) × 10^?5M_⊙ and (4?8) × 10^?5M_⊙ The dust envelope of V1016 Cyg disperses slower than that of HM Sge by almost a factor of 25.     

Infrared photometry of Sakurai’s object (V4334 Sgr) in 1996–1999

The infrared photometric observations of V4334 Sgr in 1996–1999 are presented. Together with optical data, they have allowed us to accurately estimate the bolometric flux from this star and to investigate the structure of its dust envelope over the above period. The star is shown to have passed through four well-defined stages in these four years as it moved backward along the post-AGB track, and it now appears to have started moving forward after a halt. At the first stage (1996), there was no dust in the star’s envelope. Its visual brightness slightly increased, and it reddened in the entire observed spectral range. The bolometric flux also gradually rose. At the second stage (1997), an optically thick dust envelope condensed around the star, which, however, essentially did not manifest itself at optical wavelengths. The bolometric flux continued to rise through an increase in the star’s infrared brightness alone; the rate of its rise also increased. At the third stage (1998–March 1999), V4334 Sgr entered the R CrB phase. First two shallow minima and then two deep minima were observed at optical wavelengths. The star appreciably reddened during the deep minima. The bolometric flux ceased to rise and began to gradually fall in the second half of 1998. At the fourth stage (since March 1999 up until now), V4334 Sgr has been at a protracted deep minimum, which is atypical of the R CrB stars. The bolometric flux between March and October underwent no significant variations. We describe the structure of the dust envelope around V4334 Sgr since its formation. From June 1997 until July 1998, the optical depth of the dust shell, its inner and outer radii, and its mass increased by factors of ～2.2, ～2.0, 2.3, and ～10, respectively. In July 1998, τ(V)≈2.3, R _{d, in}≈7.4×10¹⁴ cm, R _{d, in}/R _{d, out}≈0.7(R _{d, in}/R _*≈47), and M _dust≈1.6×10^?7 M _⊙.     

Infrared photometry of Sakurai’s object (V4334 Sgr) in 2000

The infrared photometric observations of V4334 Sgr in 2000 are presented. They show that a gradual, but nonmonotonic increase in the optical depth of its dust envelope, which was formed early in 1997, had continued until the mid-summer. In July 1999 and July 2000, τ(1.25 µm)≈7.7 and 11.3, respectively. From July through October 2000, the optical depth decreased appreciably. From October 1998 (the first deep minimum of visual brightness) until now, the amplitude of the bolometric-magnitude variations in V4334 Sgr is $ \sim 0^m .5$ . The relation between the bolometric and L magnitudes (m _bol, L) can be fitted by a linear function, m _bol = 1.25L + 4.04. In the dust-envelope model chosen, the percentage of large (a _gr=0.2–0.3 µm) dust grains by particle number increased by a factor of ～4. In the summer of 2000, their fraction by mass was ～78%, and they mainly contributed to the optical depth of the dust envelope. No appreciable correlation between optical depth and bolometric flux was observed.     

Nova Cygni 1975 (V1500 Cyg) in 2000–2009 and the nature of its synodic period

Multicolor photometric data are presented for the asynchronous polar V1500 Cyg during 2000–2009, i.e., 23–35 years after its outburst. Some examples of individual light curves of the system are shown. An analysis of these reveals large variations in its brightness and color with the phase of the orbital period owing to a “reflection effect” caused by reradiation from the side of the red dwarf facing the hot white dwarf and heated by its hard ultraviolet radiation. The variations in the O-C residuals and in the maximum intensity with the phase of the synodic period are illustrated. It is found that the amplitude A of the orbital fluctuations increases in proportion to the intensity I at a rate dA/dI=0.64. This behavior of V1500 Cyg is most likely caused by periodic shading of the illuminated part of the red dwarf, where the degree of shading depends on the phase of the synodic cycle.     

OBITUARY: Mukul Kundu (1930 – 2010)

Obituary

OBITUARY: Mukul Kundu (1930 – 2010)     

The European Planetary Congress 2010 (Rome,September 19–25, 2010)

Almost 900 reports were presented at the planetary congress EPSC 2010 in Rome. The congress took place in the building of the Pontifical University of Saint Thomas Aquinas. The report by A. Morbidelli et al. “The Origin of the Small Mass of Mars” was among the reports that drew the greatest attention of the participants.     

Far infrared photometry of planets: Saturn and Venus: Volume 38, Number 3 (1979), in the article,by R. Courtin,P. Léna,M. De Muizon,D. Rouan,C. Nicollier,and J. Wijnbergen,pp. 411–419

The global distribution of existing lunar topography suffers from a lack of measurements of far-side radii because of the sparsity of data types in the nonequatorial regions. This paper presents determinations of far-side lunar radii based on the reduction of photogrammetric measurements derived from selected Apollo 16 trans-Earth phase photographs. The regions covered in this analysis lie west of Mare Moscoviense between longitudes 90 and 130°E and latitudes 10 and 60°N. The determinations are made using control points appearing on both NASA topographic orthophoto maps and the Apollo 16 photographs. The estimated lunar radii are referred to these control points and determined with a relative accuracy of 500 m. The new lunar radii are used to generate a topographic map covering the area investigated. The map shows that, with the given spatial density of surface festures measured, basin-sized features can be resolved. In particular, the far-side craters Fabry, Riemann, and Szilard comprise a topographically depressed region about 500 km in diameter centered at 120°E and 38.5°N. The floor of this basin is 2.4 to 3.4 km below the reference sphere of 1738.0 km and 4.8 to 5.8 km below the northern rim of the basin. A comparison of the depth of the unfilled basin with the depths of maria-filled front-side basins leads to the conclusion that basalt fill of the near-side maria may be 2 km deep. The topographic map shows good correlation with geologic provinces of young plains and cratered terra in the far-side highland region investigated. Lack of correlation between sampled values of the state-of-the-art 16th-order and 16th-degree harmonic gravity field model and corresponding topographical values leads to the conclusion that the far-side region investigated is isostatically compensated.     

Comment on “Radiation History of Fossil Meteorites from Sweden” by V.A. Alexeev (2010), solar system research, 44, 311–319

We dispute the claim by Alexeev (2010) that the numerous fossil meteorites found in mid-Ordovician sediments in southern Sweden can be explained by a single large meteorite shower some 470 million years ago, and—in particular—that the reported variable cosmic ray exposure ages derived from cosmogenic ²¹Ne in chromite grains extracted from the fossil meteorites actually reflect variable contributions of nucleogenic ²¹Ne instead.     

The Greenwich Photo-heliographic Results (1874 – 1976): Summary of the Observations, Applications, Datasets, Definitions and Errors

The measurements of sunspot positions and areas that were published initially by the Royal Observatory, Greenwich, and subsequently by the Royal Greenwich Observatory (RGO), as the Greenwich Photo-heliographic Results (GPR), 1874?–?1976, exist in both printed and digital forms. These printed and digital sunspot datasets have been archived in various libraries and data centres. Unfortunately, however, typographic, systematic and isolated errors can be found in the various datasets. The purpose of the present paper is to begin the task of identifying and correcting these errors. In particular, the intention is to provide in one foundational paper all the necessary background information on the original solar observations, their various applications in scientific research, the format of the different digital datasets, the necessary definitions of the quantities measured, and the initial identification of errors in both the printed publications and the digital datasets. Two companion papers address the question of specific identifiable errors; namely, typographic errors in the printed publications, and both isolated and systematic errors in the digital datasets. The existence of two independently prepared digital datasets, which both contain information on sunspot positions and areas, makes it possible to outline a preliminary strategy for the development of an even more accurate digital dataset. Further work is in progress to generate an extremely reliable sunspot digital dataset, based on the programme of solar observations supported for more than a century by the Royal Observatory, Greenwich, and the Royal Greenwich Observatory. This improved dataset should be of value in many future scientific investigations.     

Preface: Frontiers in Astrophysics(Ⅱ)——A special issue dedicated to the 20th anniversary of RAA(2001–2020)

On the arrival of the 20 th anniversary of the journal, Research in Astronomy and Astrophysics(RAA), we see rapid progress in the frontiers of astronomy and astrophysics. To celebrate the birth and growth of RAA, a special issue consisting of 11 invited reviews from more than 30 authors, mainly from China, has been organized. This is the second volume of the special issues entitled Frontiers in Astrophysics published in RAA. The publication aims at evaluating the current status and key progress in some frontier areas of astronomy and astrophysics with a spirit of guiding future studies.     

The Interaction Between Coronal Mass Ejections and Streamers: A Statistical View over 15 Years (1996 – 2010)

We report on the statistical analysis of the interaction between coronal mass ejections (CMEs) and streamers based on 15 years (from 1996 to 2010 inclusive) of observation of the solar corona with the LASCO-C2 coronagraph. We used synoptic maps and improved the method of analysis of past investigations by implementing an automatic detection of both CMEs and streamers. We identified five categories of interaction based on photometric and geometric variations between the pre- and post-CME streamers: “brightening”, “dimming”, “emergence”, “disappearance”, and “deviation”. A sixth category, “no change”, included all cases where none of the above variations is observed. A “global set” of 21?242 CMEs was considered as well as a subset of the 10 % brightest CMEs (denoted “top-ten”) and three typical periods of solar activity: minimum, intermediate, and maximum. We found that about half of the global population of CMEs are not associated with streamers, whereas 93 % of the 10 % brightest CMEs are associated. When there is a CME-streamer association, approximately 95 % of the streamers experience a change, either geometric or radiometric. The “no change” category therefore amounts to approximately 5 %, but this percentage varies from 1?–?2 % during minimum to 7?–?8 % during intermediate periods of activity; values of 3?–?5 % are recorded during maximum. Emergences and disappearances of streamers are not dominant processes; they constitute 16?–?17 % of the global set and 23 % (emergence) and 28 % (disappearance) of the “top-ten” set. Streamer deviations are observed for 57 % and 70 % of, respectively, the global set and “top-ten” CMEs. The cases of dimming and brightening are roughly equally present and each case constitutes approximately 30?–?35 % of either set, global or “top-ten”.     

Spectrum analysis of Jupiters great red spot parameters: area,rotation, latitude and longitude (1963–67)

Spectrum analysis of Jupiters great red spot area, rotation, longitude, and latitude, for the period 1963–1967, has been performed. The methods of maximum entropy, power spectrum (Blackman–Tukey approach), Fourier, and autocorrelation have been employed to detect periodicities in the variation of these parameters. The method of successive approximations was applied to the area time-series, and periods of 25, 16, 5 and 3 months and a trend ∼32 months were identified and an analytical expression fit was given, with an accuracy of 78%. Only some periods (6–18 months) describe the main trends of the variation, the shorter (2–5 months) exhibit a stochastic variability, while the longer ones which approach the total record represent a trend. The obtained significant periods and long term trends, common in all methods, are: for latitude; 3.6±0.2, 6.2±0.5, 17.5±3.0 months, a sporadic one of 14.3 months and a trend of 30–35 months, for longitude; 3.9±0.14, 7.3±0.5, 15.6±2 and 19.8±2.5 months, a sporadic one of 5±1 months, and a trend of 30–40 months; for area; 16.6±4.0 and 26±4 months, and sporadic ones 15–17 months and a trend of 32±7 months, and for rotation; 4.8±0.5, 8.3±0.4, 15.2±2.3, 20±3 months, a sporadic one of 5–6 months and a trend of 30–35 months. These periodic terms form a network of periodicities overlapping one upon each other. Various tests of significance and stationarity were applied to examine the reliability and variability of the periodic components.The results of these periodic/quasi-periodic components are discussed in relation to the sunspot numbers, cometary impacts and Jovian atmospheric features.     

Erratum to “Juno,the angular momentum of Jupiter and the Lense–Thirring effect” [New Astronomy 15 (2010) 554–560]

I correct some errors, disclosed in the aforementioned paper, concerning the long-term precessions due to the multipolar expansion of the gravitational potential of Jupiter. The conclusions of the paper turn out to be even enforced since the systematic uncertainties on the Lense–Thirring signature due to the zonals are slightly reduced.