Pole coordinates of the asteroids 9 metis, 22 kalliope,and 44 Nysa

By means of new photoelectric observations made in 1974 an attempt to determine the poles of asteroids 9 and 44 was made. Following a method based upon the magnitude-aspect and amplitude-aspect relations, the coordinates of the poles for 9 and 44 were found to be, respectively, λ₀ = 191° ± 5°, β₀ = 56° ± 6° and λ₀ = 100° ± 10°, β₀ = 50° ± 10°. The previously published pole for asteroid 22, λ₀ = 215° ± 10°, β₀ = 45° ± 15°, was confirmed. From its phase relation we determined the phase coefficient of 44 Nysa, a very high albedo object (p_v = 0.377). The very low phase coefficient obtained (β_v = 0.018 mag/deg) agrees very well with an inverse relation between geometrical albedo and phase coefficient. The results are summarized in a table.     

Astrometric and photometric studies of the asteroid 2008 TC3

Near real time astrometric and photometric observations of the asteroid 2008 TC3, discovered 19 hours before it fell to Earth in the area of northern Sudan, were conducted on the night of October 6–7, 2008, using an automated telescope ZA-320M of the Pulkovo Observatory. In the interval of 4 h, 270 observations in the integral band of the telescope were performed, which was about one-third of all global observations of the asteroid. Based on the analysis of all cases, physical parameters of the asteroid were assessed. The estimates of the absolute magnitude of the asteroid (M _V = 30.6 ± 0.4 μm), its size (4.8 ± 0.8 m), and weight (131 ± 5 t) were obtained. A frequency analysis of the observational series was conducted, which helped to detect the periodicity in the brightness variation of the asteroid. The elements of the heliocentric orbit of the asteroid were refined. The trajectory of the asteroid, taking into account the atmospheric drag and nonsphericity of the Earth, was simulated.     

Photometric observations and modelling of the asteroid 85 Io in conjunction with data from an occultation event during the 1995–96 apparition

The asteroid 85 Io has been observed using CCD and photoelectric photometry on 18 nights during its 1995–96 and 1997 apparitions. We present the observed lightcurves, determined colour indices and modelling of the asteroid spin vector and shape. The colour indices (U-B = 0.35±0.02, B-V = 0.66±0.02, V-R = 0.34±0.02, R-I = 0.36±0.02) are as expected for a C-type asteroid. The allowed spin vector solutions have the pole co-ordinates λ₀ = 285±4°, β₀ = −52±9° or λ₀ = 108±10°, β₀ = −46±10° and λ₀ = 290±10°, β₀ = −16±10° with a retrograde sense of rotation and a sidereal period P_sid = 0^d.286463±0^d.000001. During the 1995–96 apparition the International Occultation Time Association (IOTA) observed an occultation event by 85 Io. The observations and modelling presented here were analysed together with the occultation data to develop improved constraints on the size of the asteroid. The derived value of 164 km is about 5% larger than the IRAS diameter. © 1999 Elsevier Science Ltd. All rights reserved.     

Polarimetric and Photometric Phase Effects Observed on Transneptunian Object (29981) 1999 TD10

The Kuiper-Belt Object (29981) 1999 TD₁₀, classified as a Scattered-Disk Object, has been observed at three different phase angles with the ESO 8.2-m VLT and FORS 1 instrument in polarimetric mode in November and December 2003. These observations have been used to compute the Stokes parameter q, which represents the linear polarization degree. We have also used the previously published photometric observations to improve the R-band phase function. The main conclusions are as follows: (i) a negative linear polarization degree decreasing with phase angle α up to, at least, α=3°, (ii) for α=3°, (iii) a possible color effect between the R and V band, the polarization degree being more negative in R. The R-band polarimetric observations can be explained by the coherent-backscattering mechanism and fitted by a two-component Rayleigh-scatterer model for a spherical small body. The rotation period of 15.382±0.001 h published by Mueller et al. (2004, Icarus 171, 506–515) and Choi et al. (2003, Icarus 165, 101–111) is confirmed. The R-band phase curve provides H=8.35±0.02 and G=−0.25±0.022 parameters with the IAU H–G formalism.Based on observations obtained at the Cerro Paranal observatory of the European Southern Observatory (ESO) in Chile.     

Galactic kinematics from OB3 stars with distances determined from interstellar Ca II lines

Based on data for 102 OB3 stars with known proper motions and radial velocities, we have tested the distances derived by Megier et al. from interstellar Ca II spectral lines. The internal reconciliation of the distance scales using the first derivative of the angular velocity of Galactic rotation Ω′₀ and the external reconciliation with Humphreys’s distance scale for OB associations refined by Mel’nik and Dambis show that the initial distances should be reduced by ≈20%. Given this correction, the heliocentric distances of these stars lie within the range 0.6–2.6 kpc. A kinematic analysis of these stars at a fixed Galactocentric distance of the Sun, R ₀ = 8 kpc, has allowed the following parameters to be determined: (1) the solar peculiar velocity components (u _⊙, v _⊙, ω _⊙) = (8.9, 10.3, 6.8) ± (0.6, 1.0, 0.4) km s⁻¹; (2) the Galactic rotation parameters Ω₀ = −31.5 ± 0.9 km s⁻¹ kpc⁻¹, Ω′₀ = +4.49 ± 0.12 km s⁻¹ kpc⁻², Ω″₀ = −1.05 ± 0.38 km s⁻¹ kpc⁻³ (the corresponding Oort constants are A = 17.9 ± 0.5 km s⁻¹ kpc⁻¹, B = −13.6 ± 1.0 km s⁻¹ kpc⁻¹ and the circular rotation velocity of the solar neighborhood is |V ₀| = 252 ± 14 km s⁻¹); (3) the spiral density wave parameters, namely: the perturbation amplitudes for the radial and azimuthal velocity components, respectively, f _R = −12.5±1.1 km s⁻¹ and f _ϑ = 2.0 ± 1.6 km s⁻¹; the pitch angle for the two-armed spiral pattern i = −5.3° ± 0.3°, with the wavelength of the spiral density wave at the solar distance being λ = 2.3 ± 0.2 kpc; the Sun’s phase in the spiral wave x _⊙ = −91° ± 4°.     

Photometric study of the W UMa eclipsing binaries VW LMi and BX Dra

New ephemeris and the absolute parameters—masses, radii and luminosities—of the contact systems VW LMi and BX Dra have been obtained, by means of the analysis of the minima data available in the literature (for the determination of the ephemeris) and combining the previously published spectroscopic information and the results of the Wilson-Devinney method using photometric data (for the determination of the absolute parameters). The VW LMi O−C analysis confirms the multiplicity of the system detected previously from the spectroscopic data. Masses of the VW LMi contact system primary and secondary components are 1.67 ± 0.02M _⊙ and 0.70 ± 0.02M _⊙, respectively. The corresponding radii are 1.709 ± 0.007R _⊙ and 1.208 ± 0.006R _⊙, respectively. For the BX Dra contact system the masses are 2.19 ± 0.13M _⊙ and 0.63 ± 0.06M _⊙, and the radii, 2.13 ± 0.04R _⊙ and 1.26 ± 0.03R _⊙, for the primary and secondary, respectively. In both cases, the estimated luminosities seem to be slightly greater that the values derived from the Hipparcos distances.     

The kinematics of Trapezium-type systems

Summary In this paper the results of the research of the stars proper motions Trapezium components are reported. They are: the galactic coordinates of the solar aprx and the Sun velocity (L _⊙=43±18°,B _⊙=+28±13°,V _⊙=13±4 km s⁻¹), the dispersion of peculiar velocities in the direction of the galactic coordinates for the above mentioned stars (σ _l =±11 km s⁻¹, σ _b =±7 km s⁻¹).The attained accuracy of the proper motions (±0.005″ yr⁻¹) is shown to be insufficient to the study of internal space motions in these systems. At present the work to increase the relative proper motions accuracy for multiple system components and to improve reductions from the relative to absolute proper motions, is being carried out in the Main Astronomical Observatory (Academy of Sciences of the Ukrainian SSR). The new catalogue of the AGK3 stars is composed now in the vicinity of the galactic equator in order to improve reductions from the relative to absolute proper motions. The r.m.s. errors of the proper motions, obtained in the AGK3 system, are ±0.005″ yr⁻¹.     

Pole coordinates of the asteroid 511 Davida as determined via the Amplitude-Magnitude method

The Amplitude-Magnitude (AM) method is used for the pole determination of the asteroid 511 Davida, using observations from six oppositions. The possible North poles are found to be λ₁ = 92° ± 7°; β₁ = 33° ± 6°, and λ₂ = 303° ± 4°; β₂ = 34° ± 5°, when scattering effect is not taken into account. When scattering is accounted for, solutions not significantly different from (λ₁, β₁) and (λ₂, β₂) are obtained. The moderately eccentric and inclined orbit of 511 Davida does not allow us to distinguish between the two pole solutions. A comparison with other methods is necessary in order to make a definitive choice.     

Solar Cycle Predictions based on Solar Activity at Different Solar Latitudes

Many methods of predictions of sunspot maximum number use data before or at the preceding sunspot minimum to correlate with the following sunspot maximum of the same cycle, which occurs a few years later. Kane and Trivedi (Solar Phys. 68, 135, 1980) found that correlations of R _z(max) (the maximum in the 12-month running means of sunspot number R _z) with R _z(min) (the minimum in the 12-month running means of sunspot number R _z) in the solar latitude belt 20° – 40°, particularly in the southern hemisphere, exceeded 0.6 and was still higher (0.86) for the narrower belt > 30° S. Recently, Javaraiah (Mon. Not. Roy. Astron. Soc. 377, L34, 2007) studied the relationship of sunspot areas at different solar latitudes and reported correlations 0.95 – 0.97 between minima and maxima of sunspot areas at low latitudes and sunspot maxima of the next cycle, and predictions could be made with an antecedence of more than 11 years. For the present study, we selected another parameter, namely, SGN, the sunspot group number (irrespective of their areas) and found that SGN(min) during a sunspot minimum year at latitudes > 30° S had a correlation +0.78±0.11 with the sunspot number R _z(max) of the same cycle. Also, the SGN during a sunspot minimum year in the latitude belt (10° – 30° N) had a correlation +0.87±0.07 with the sunspot number R _z(max) of the next cycle. We obtain an appropriate regression equation, from which our prediction for the coming cycle 24 is R _z(max )=129.7±16.3.     

Astrometric and photometric studies of the 2009 WZ104 asteroid as it approached the earth

The astrometric and photometric observations of the potentially hazardous 2009 WZ104 asteroid were carried out at the MTM-500M and ZA-320M automatic telescopes of the Pulkovo Observatory in December 2009. A total of 686 observations were performed in the integral band and 146 observations with B, V, R, and I filters on an arc of the orbit of 17°; these accounted for about 77% of all worldwide observations (). On the basis of the obtained data, the orbit was improved and an estimation of the physical parameters of the asteroid was made. Estimates of the absolute stellar magnitude of the asteroid, H = (20.52 ± 0.04) ^m , as well as its size and mass, were obtained. The taxonomic class of the 2009 WZ104 asteroid (R or Q) was determined. A frequency analysis of the series of observations was carried out; periodicities in the asteroid’s light variation were revealed using this method.     

Photometric observations of Earth‐impacting asteroid 2008 TC3

Abstract– A calibrated lightcurve is presented of the near‐Earth asteroid 2008 TC₃, obtained before it impacted Earth on October 7, 2008. The asteroid was observed in unfiltered images from the end of astronomical twilight until the object entered Earth’s shadow about 2 h later. The observations covered a wide range of phase angles from 14.79° to 2.93°, during which the asteroid ranged from 82,000 km to 29,000 km distance from the observer. A method is presented for obtaining photometrically filtered brightness values for the asteroid using unfiltered imaging techniques. Over 1,700 images of the asteroid produce a lightcurve with a peak‐to‐peak variation in V of 0.76 magnitude. Analysis of the lightcurve yields values for H = 30.86 ± 0.01 and G = 0.33 ± 0.03. Combined with other constraints on the kinetic energy and diameter of the asteroid, which suggest a low 1.8 g cm^?3 density and albedo 0.05 ± 0.01, the value of H implies an asteroid of about 4.1 m in diameter, 28 m³ in volume, and 51,000 kg in mass. The determined value of G is out of range for normal, larger asteroids of albedo 0.05–0.15.     

554 Peraga—an asteroid with unusual polarization properties?

This paper presents the results of polarization observations of asteroid 554 Peraga obtained with the UBVRI polarimeter using the 1.25 m telescope of the Crimean Astrophysical Observatory down to phase angles of 3.1°–16.6° from October to November 2006. The asteroid’s polarization phase curve is shown to have a negative branch with the parameters P _min = −1.7% and α_min = 8.4°, which is typical of C-type asteroids. However, these data contradict the results of Zellner and Gradie (1976) obtained in March 1975 that the reflected light from the asteroid’s surface is positively polarized, ≈1% at phase angles of 8°–10°. Since the asteroid’s ecliptic longitudes differ by 160°-145° for the two observation periods, we discuss the possibility that the two sets of observations refer to the asteroid’s two hemispheres with different polarimetric properties.     

Does the proton-to-electron mass ratio μ = m p /m e vary in the course of cosmological evolution?

The possible cosmological variation of the proton-to-electron mass ratio μ = m _p /m _e was estimated by measuring the H₂ wavelengths in the high-resolution spectrum of the quasar Q 0347-382. Our analysis yielded an estimate for the possible deviation ofμ value in the past, 10 Gyr ago: for the unweighted valueΔ μ / μ = (3.0±2.4)×10^-5; for the weightedvalueΔ μ / μ = (5.02±1.82)×10^-5.Since the significance of the both results does not exceed3σ, further observations are needed to increase the statistical significance. In any case, this result may be considered as the most stringent estimate on an upper limit of a possible variation of μ (95% C.L.):|Δ μ / μ| < 8× 10^-5 .This value serves as an effective tool for selection of models determining a relation between possible cosmological deviations of the fine-structure constant α and the elementary particle masses (m_p, m_e, etc.). This revised version was published online in July 2006 with corrections to the Cover Date.     

Bidirectional reflectance distribution function measurements of the Winchcombe meteorite using the Visible Oxford Space Environment Goniometer

A laboratory study was performed using the Visible Oxford Space Environment Goniometer in which the broadband (350–1250 nm) bidirectional reflectance distribution function (BRDF) of the Winchcombe meteorite was measured, across a range of viewing angles—reflectance: 0°–70°, in steps of 5°; incidence: 15°, 30°, 45°, and 60°; and azimuthal: 0°, 90°, and 180°. The BRDF dataset was fitted using the Hapke BRDF model to (1) provide a method of comparison to other meteorites and asteroids, and (2) to produce Hapke parameter values that can be used to extrapolate the BRDF to all angles. The study deduced the following Hapke parameters for Winchcombe: w = 0.152 ± 0.030, b = 0.633 ± 0.064, and h_S = 0.016 ± 0.008, demonstrating that it has a similar w value to Tagish Lake (0.157 ± 0.020) and a similar b value to Orgueil (0.671 ± 0.090). Importantly, the surface profile of the sample was characterized using an Alicona 3D® instrument, allowing two of the free parameters within the Hapke model φ and $\overline{\theta }$, which represent porosity and surface roughness, respectively, to be constrained as φ = 0.649 ± 0.023 and $\overline{\theta }$ = 16.113° (at 500 μm size scale). This work serves as part of the characterization process for Winchcombe and provides a reference photometry dataset for current and future asteroid missions.     

CCD Polarimetry of Near-Earth Asteroid 2014 JO25 and Comet 41P/Tuttle–Giacobini–Kresák at the Prime Focus of the 2.6-m Shajn Telescope of the Crimean Astrophysical Observatory

The results of the first polarimetric measurements of near-Earth asteroid 2014 JO₂₅ and comet 41P/Tuttle-Giacobini-Kresák performed on April 19, 2017, with a CCD sensor at the prime focus (f/3.85) of the 2.6-m Shajn Telescope of the Crimean Astrophysical Observatory in the R filter are reported. The degree of linear polarization of the asteroid is P = 2.69 ± 0.44% at a phase angle of 55.6°, which is typical of an S-type asteroid. Its geometric albedo is ρ_v ≈ 0.2. A digital filter applied to the direct image of the comet reveals a jet and a tail directed toward the Sun (PA = 45.1°) and away from it (PA = 241.2°), respectively, in the coma. The maximum degree of linear polarization in the near-nucleus region of the comet is 18% at a phase angle of 69.8°. The polarization decreases to 16.2–10.7% in coma regions with a radius of 865–4856 km. Various factors affecting the maximum degree of polarization and the polarization-degree distribution over the coma are discussed.

     

A high galactic latitude HI 21 cm-line absorption survey using the GMRT: II. Results and interpretation

We have carried out a sensitive high-latitude (|b| > 15°) HI 21 cm-line absorption survey towards 102 sources using the GMRT. With a 3σ detection limit in optical depth of ∼ 0.01, this is the most sensitive HI absorption survey. We detected 126 absorption features most of which also have corresponding HI emission features in the Leiden Dwingeloo Survey of Galactic neutral Hydrogen. The histogram of random velocities of the absorption features is well-fit by two Gaussians centered at V_1sr ∼ 0 km s⁻¹ with velocity dispersions of 7.6 ± 0.3 km s⁻¹ and 21 ± 4 km s⁻¹ respectively. About 20% of the HI absorption features form the larger velocity dispersion component. The HI absorption features forming the narrow Gaussian have a mean optical depth of 0.20 ± 0.19, a mean HI column density of (1.46 ± 1.03) × 10²⁰ cm⁻², and a mean spin temperature of 121 ± 69 K. These HI concentrations can be identified with the standard HI clouds in the cold neutral medium of the Galaxy. The HI absorption features forming the wider Gaussian have a mean optical depth of 0.04 ± 0.02, a mean HI column density of (4.3 ± 3.4) × 10¹⁹ cm⁻², and a mean spin temperature of 125 ± 82 K. The HI column densities of these fast clouds decrease with their increasing random velocities. These fast clouds can be identified with a population of clouds detected so far only in optical absorption and in HI emission lines with a similar velocity dispersion. This population of fast clouds is likely to be in the lower Galactic Halo.     

Electron Temperatures and Flow Speeds of the Low Solar Corona: MACS Results from the Total Solar Eclipse of 29 March 2006 in Libya

An experiment was conducted in conjunction with the total solar eclipse on 29 March 2006 in Libya to measure both the electron temperature and its flow speed simultaneously at multiple locations in the low solar corona by measuring the visible K-coronal spectrum. Coronal model spectra incorporating the effects of electron temperature and its flow speed were matched with the measured K-coronal spectra to interpret the observations. Results show electron temperatures of (1.10±0.05) MK, (0.70±0.08) MK, and (0.98±0.12) MK, at 1.1 R _⊙ from Sun center in the solar north, east and west, respectively, and (0.93±0.12) MK, at 1.2 R _⊙ from Sun center in the solar west. The corresponding outflow speeds obtained from the spectral fit are (103±92) km s⁻¹, (0+10) km s⁻¹, (0+10) km s⁻¹, and (0+10) km s⁻¹. Since the observations were taken only at 1.1 R _⊙ and 1.2 R _⊙ from Sun center, these speeds, consistent with zero outflow, are in agreement with expectations and provide additional confirmation that the spectral fitting method is working. The electron temperature at 1.1 R _⊙ from Sun center is larger at the north (polar region) than the east and west (equatorial region).     

Spectroscopic Orbit of the Eclipsing Binary AI Draconis

New radial velocity measurements of the Algol-type eclipsing binary AI Dra, based on Reticon observations, are presented. The velocity measures themselves are based on fitting theoretical profiles, generated by a physical model of the binary, to the observed cross-correlation function (ccf). Such profiles match this function very well, much better in fact that Gaussian profiles which are generally used. Measuring the ccf's with Gaussian profiles yields following results: m_p sin³ i=2.55± 0.05m_⊙, m_s sin³ i = 1.14 ± 0.03m_⊙, (a_p + a_s) sin i=7.34 ±0.05R_⊙, and m_p/m_s =2.23± 0.05. Where as measuring the ccf's with theoretical profiles yields a mass ratio of 2.33 and following results: m_p sin³ i=2.84± 0.05m_⊙, m_s sin³ i=1.22 ± 0.03m_⊙, (a_p +a_s) sin i=7.56± 0.05R_⊙. The system comprising a semi-detached configuration. From the solution of a previously published light curved and combining it's results with the spectroscopic orbit, one can lead to the following physical parameters: m_p =2.99m_⊙, m_s =1.28m_⊙, > T_p < =9600 K, > T_s < =5400 K, > R_p < =2.35R_⊙, > R_s < =2.12R_⊙. The system comprising an AO primary and a secondary of G2 spectral type. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the Stability of High Inclined L4 and L5Trojans

The orbits of real asteroids around the Lagrangian points L₄ and L ₅of Jupiter with large inclinations (i > 20°) were integrated for 50 Myrs. We investigated the stability with the aid of the Lyapunov characteristic exponents (LCE) but tested also two other methods: on one hand we integrated four neighbouring orbits for each asteroid and computed the maximum distance in every group, on the other hand we checked the variation of the Delaunay element H of the asteroid. In a second simulation – for a grid of initial eccentricity versus initial inclination – we examined the stability of the orbits around both Lagrangian points for 20° < i < 55° and 0.0 < e < 0.20. For the initial semimajor axes we have chosen the one ofJupiter(a = 5.202 AU). We determined the stability with the aid of the LCEs and also the maximum eccentricity of the orbits during the whole integration time. The region around L₄ turned out to be unstable for large inclinations and eccentricities (i > 55° and e > 0.12). The stable region shrinks for orbits around L₅: we found that they become unstable already for i > 45° and e > 0.10. We interpret it as a first hint why we observe more Trojans around the leading Lagrangian point. The results confirm the stability behaviour of the real Trojans which we computed in the first part of the paper.     

CCD BV and 2MASS photometric study of the open cluster NGC 1513

We present CCD BV and JHK _s 2MASS photometric data for the open cluster NGC 1513. We observed 609 stars in the direction of the cluster up to a limiting magnitude of V∼19 mag. The star-count method showed that the centre of the cluster lies at α ₂₀₀₀=04 ^h 09 ^m 36 ^s , δ ₂₀₀₀=49°28^′43^″ and its angular size is r=10 arcmin. The optical and near-infrared two-colour diagrams revealed the colour excesses in the direction of the cluster as E(B−V)=0.68±0.06, E(J−H)=0.21±0.02 and E(J−K _s )=0.33±0.04 mag. These results are consistent with normal interstellar extinction values. Optical and near-infrared Zero Age Main-Sequences (ZAMS) provided an average distance modulus of (m−M)₀=10.80±0.13 mag, which can be translated into a distance of 1440±80 pc. Finally, using Padova isochrones we determined the metallicity and age of the cluster as Z=0.015±0.004 ([M/H]=−0.10±0.10 dex) and log (t/yr)=8.40±0.04, respectively.