- ID:
- ivo://CDS.VizieR/J/A+AS/103/83
- Title:
- Line identifications in a fireball spectrum
- Short Name:
- J/A+AS/103/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 305 emission lines were found in a spectrum of a fireball of -9th magnitude. The identification of most of the lines is given. Also a detailed tracing of the spectrum in the range 3600-6600{AA} is presented. The tracing contains also computed synthetic spectrum and both spectra can be easily compared. The following species were found in the spectrum: Fe I, Na I, Mg I, Al I, Ca I, Ti I, Cr I, Mn I, Ni I, Mg II, Si II, Ca II, Fe II, FeO, probably also Si I, Ba II, C_2_, and possibly V I, Co I, Cu I, Ti II. The presence of other chemical elements in meteor spectra is discussed.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/603/A87
- Title:
- Local production rates of 67P/CG from MIRO
- Short Name:
- J/A+A/603/A87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using spectroscopic and continuum data measured by the MIRO instrument on board Rosetta of comet 67P/Churyumov-Gerasimenko, it is possible to derive and track the change in the water production rate, to learn how the outgassing evolves with heliocentric distance. The MIRO data are well suited to investigate the evolution of 67P, in unprecedented spatial and temporal detail. To obtain estimates of the local effective Haser production rates we developed an efficient and reliable retrieval approach with precalculated lookup tables. We employed line area ratios (H_2_^16^O/H_2_^18^O) from pure nadir observations as the key variable, along with the Doppler shift velocity, and continuum temperature. This method was applied to the MIRO data from August 2014 until April 2016. Perihelion occurred on August 13, 2015 when the comet was 1.24AU from the Sun. During the perihelion approach, the water production rates increased by an order of magnitude, and from the observations, the derived maximum for a single observation on August 29, 2015 is (1.42+/-0.51)x10^28^. Modelling the data indicates that there is an offset in the peak outgassing, occurring 34+/-10 days after perihelion. During the pre-perihelion phase, the production rate changes with heliocentric distance as r_h_^-3.8+/-0.2^; during post- perihelion, the dependence is r_h_^-4.3+/-0.2^. The comet is calculated to have lost 0.12+/-0.06% of its mass during the perihelion passage, considering only water ice sublimation. Additionally, this method provides well- sampled data to determine the spatial distribution of outgassing versus heliocentric distance. The time evolution is definitely not uniform across the surface. Pre- and post-perihelion, the surface temperature on the southern hemisphere changes rapidly, as does the sublimation rate with an exponent of ~-6. There is a strong latitudinal dependence on the r_h_ exponent with significant variation between northern and southern hemispheres, and so the average over the comet surface may only be of limited importance. We present more detailed regional variation in the outgassing, thereby demonstrating that the highest derived production rates originate from the Wosret, Neith, and Bes regions during perihelion.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A80
- Title:
- 122 long-period comets non-gravitational param.
- Short Name:
- J/A+A/633/A80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The original 1/a-distribution is the only observational basis for the origin of long-period comets (LPCs) and the dynamical properties of the Oort Cloud. Although they are very subtle in the motion of these comets, non-gravitational effects can cause major changes in the original semimajor axis, 1/a_ori_ We obtained reliable non-gravitational orbits for as many LPCs with small perihelion distances of q<3.1au as possible, and determined the corresponding shape of the Oort spike. We determined the osculating orbits of each comet using several data-processing methods, and selected the preferred orbit using a few specific criteria. The distribution of 1/a_ori_ for the whole comet sample was constructed using the individual Gaussian distribution we obtained for the preferred solution of each comet. The derived distribution of 1/a_ori_ for almost all known small-perihelion Oort spike comets was based on 64% of the non-gravitational orbits. This was compared with the distribution based on purely gravitational orbits, as well as with 1/a_ori_ constructed earlier for LPCs with q>3.1 au. We present a statistical analysis of the magnitudes of the non-gravitational acceleration for about 100~LPCs. The 1/a_ori_-distribution, which is based mainly on the non-gravitational orbits of small-perihelion Oort spike comets, is shifted by about 10x10^-6^au^-1^ to higher values of 1/a_ori_ compared with the distribution that is obtained when the non-gravitational effects on comet motion are ignored. We show the differences in the 1/a_ori_-distributions between LPCs with q<3.1au and those with q>3.1au. These findings indicate the important role of non-gravitational~acceleration in the motion and origin of LPCs and in the formation of the Oort Cloud.
- ID:
- ivo://CDS.VizieR/J/A+A/287/990
- Title:
- Meteor stream activity.
- Short Name:
- J/A+A/287/990
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/629/A71
- Title:
- mm-dm-sized meteoroids spectral & orbital survey
- Short Name:
- J/A+A/629/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the spectra, material properties and orbital distribution of mid-sized meteoroids. Our study aims to distinguish characteristics of different size populations of meteoroids and reveal the heterogeneity of identified meteoroid streams. The emission spectra and multi-station meteor trajectories were collected within the AMOS network observations. The sample is based on 202 meteors of -1 to -14 magnitude, corresponding to meteoroids of mm-dm in size. Overall increase of Na content compared to the population of mm-sized meteoroids was detected, reflecting weaker effects of space weathering processes on larger meteoroids. We report on very low ratio of pure iron meteoroids and the discovery of a new spectral group of Fe-rich meteors. The majority of meteoroids on asteroidal orbits were found to be chondritic. Thermal processes causing Na depletion and physical processes resulting in Na-rich spectra are described and linked to characteristically increased material strengths. Numerous major and minor shower meteors were identified in our sample, revealing various degrees of heterogeneity within Halley-type, ecliptical and sungrazing meteoroid streams.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A48
- Title:
- Mm-spectra of comets C/2001 Q2 and C/2002 T7
- Short Name:
- J/A+A/559/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The chemical composition of comets can be inferred using spectroscopic observations in submillimeter and radio wavelengths. We aim to compare the production rates ratio of several volatiles in two comets, C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR), which are generally regarded as dynamically new comets likely to originate in the Oort cloud. This type of comets is considered to be composed of primitive material that has not undergone considerable thermal processing. The line emission in the coma was measured in the comets, C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR), that were observed on five consecutive nights, 7-11 May 2004, at heliocentric distances of 1.0 and 0.7AU, respectively, by means of high resolution spectroscopic observations using the 10-m Submillimeter Telescope (SMT) at the Arizona Radio Observatory (ARO). Both objects became very bright and reached naked-eye visibility during their perihelion passage in the spring of 2004.
- ID:
- ivo://CDS.VizieR/J/ApJ/792/30
- Title:
- NEOWISE magnitudes for near-Earth objects
- Short Name:
- J/ApJ/792/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NASA's Wide-field Infrared Survey Explorer (WISE) spacecraft has been brought out of hibernation and has resumed surveying the sky at 3.4 and 4.6 {mu}m. The scientific objectives of the NEOWISE reactivation mission are to detect, track, and characterize near-Earth asteroids and comets. The search for minor planets resumed on 2013 December 23, and the first new near-Earth object (NEO) was discovered 6 days later. As an infrared survey, NEOWISE detects asteroids based on their thermal emission and is equally sensitive to high and low albedo objects; consequently, NEOWISE-discovered NEOs tend to be large and dark. Over the course of its three-year mission, NEOWISE will determine radiometrically derived diameters and albedos for ~2000 NEOs and tens of thousands of Main Belt asteroids. The 32 months of hibernation have had no significant effect on the mission's performance. Image quality, sensitivity, photometric and astrometric accuracy, completeness, and the rate of minor planet detections are all essentially unchanged from the prime mission's post-cryogenic phase.
- ID:
- ivo://CDS.VizieR/J/A+A/571/A63
- Title:
- New catalogue of one-apparition comets
- Short Name:
- J/A+A/571/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The orbits of one-apparition comets discovered in the early part of the last century have formerly been determined with very different numerical methods and assumptions on the model of the solar system, including the number of planets taken into account. Moreover, observations of the comet-minus-star-type sometimes led to determination of the comet position that are less precise than what we can derive today by using a more modern star catalogue. We aim to provide a new catalogue of cometary orbits that are derived using a completely homogeneous data treatment, accurate numerical integration, and a modern model of the solar system. We collected the complete sets of observations for investigated comets from the original publications. Then we recalculated the cometary positions for the comet-minus-star-type of observations using the Positions and Proper Motions Star Catalogue, and applied a uniform method for the data selection and weighting. As a final result, new osculating orbits were determined. Secondly, dynamical calculations were performed to the distance of 250AU from the Sun to derive original and future barycentric orbits for evolution backward and forward in time. These numerical calculations for a given object start from a swarm of virtual comets constructed using our osculating (nominal) orbit. In this way, we obtained the orbital element uncertainties of original and future barycentric orbits.
- ID:
- ivo://CDS.VizieR/J/A+A/634/L6
- Title:
- NIR spectrum of interstellar object 2I/Borisov
- Short Name:
- J/A+A/634/L6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interstellar objects (ISOs) passing through our Solar System offer a rare opportunity to probe the physical and chemical processes involved in solid body and planet formation in extrasolar systems. The main objective of our study is to search for diagnostic absorption features of water ice in the near-infrared (NIR) spectrum of the second interstellar object 2I/2019 Q4 (Borisov) and compare its ice features to those of the Solar System icy objects. We observed 2I in the NIR on three separate occasions. The first observation was made on 2019 September 19 UT using the SpeX spectrograph at the 3m IRTF and again on September 24 UT with the GNIRS spectrograph at the 8m GEMINI telescope; the last observation was made on October 09 UT with IRTF. The spectra obtained from all three nights appear featureless. No absorption features associated with water ice are detected. Spectral modeling suggests that water grains, if present, comprise no more than 10% of the coma cross section. The comet consistently exhibits a red D-type like spectrum with a spectral slope of about 6% per 1000~\AA, which is similar to that of 1I/'Oumuamua and is comparable to Solar System comets.
- ID:
- ivo://CDS.VizieR/J/A+AS/146/73
- Title:
- Nuclear magnitudes of Jupiter family comets
- Short Name:
- J/A+AS/146/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of a sample of 105 Jupiter family (JF) comets (defined as those with Tisserand constants T>2 and orbital periods P<20yr) is presented with our ``best estimates'' of their absolute nuclear magnitudes H_N_=V(1,0,0). The catalog includes all the nuclear magnitudes reported after 1950 until August 1998 that appear in the International Comet Quarterly Archive of Cometary Photometric Data, the Minor Planet Center (MPC) data base, IAU Circulars, International Comet Quarterly, and a few papers devoted to some particular comets, together with our own observations. Photometric data previous to 1990 have mainly been taken from the Comet Light Curve Catalogue (CLICC) compiled by Kamel (1991, The comet light curve catalogue/atlas. I. The compiled observations. Uppsala Univ. Reprocentralen HSC). Most absolute nuclear magnitudes are found in the range 15-18, with no magnitudes fainter than H_N_~19.5.
