- ID:
- ivo://CDS.VizieR/J/A+A/656/A160
- Title:
- Comet C/2020 F3 (NEOWISE) emission lines
- Short Name:
- J/A+A/656/A160
- Date:
- 21 Mar 2022 09:16:33
- Publisher:
- CDS
- Description:
- Comet C/2020 F3 (NEOWISE) is considered to be the brightest comet observed in the northern hemisphere since the passage of comet C/1995 O1 (Hale-Bopp) in 1997. Since the study of comets offers a unique opportunity to investigate the early stages of the formation and evolution of our Sun and the Solar System, we obtained high-resolution optical spectra (R={lambda}/{Delta}{lambda}=115000) of comet NEOWISE. The unique passage and its brightness yielded spectra with a large number of emission lines, providing information on the coma composition and the physical and chemical processes occurring in the nucleus. The spectra have been used to generate a catalog of emission lines to be used for future studies of comets since there are no catalogs in the literature with such a high spectral resolution. Two high-resolution spectra of comet NEOWISE were obtained, on 26 July 2020 (geocentric distance of 0.7au) and 5 August 2020 (geocentric distance of 0.89au), with the High Accuracy Radial velocity Planet Searcher for the Northern hemisphere (HARPS-N) echelle spectrograph installed on the 360cm Telescopio Nazionale Galileo (TNG). The spectra cover the range between 383 and 693nm, and have been extracted using the HARPS-N Data Reduction Pipeline. To analyze the spectra and compile the high-resolution catalog, we collected several laboratory molecular line lists that cover the same wavelength range as that of our spectra. To validate the final identification, we compared our catalog with other atlases that resulted from the spectral analysis of other comets. We generate a high-spectral-resolution catalog of emission lines observed in comet NEOWISE, providing the identification for 4488 lines. We found cometary lines due to CN, CH, C_2_, C_3_, and NH_2_ and atomic lines due to NaI and [OI].
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/367/1049
- Title:
- Comet C/1995 O1 (Hale-Bopp) emission lines
- Short Name:
- J/A+A/367/1049
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution and high signal-to-noise ratio spectra of Comet C/1995 O1 (Hale-Bopp), which provided continuous wavelength coverage from 5500{AA} to 8500{AA} and partial coverage from 4000{AA} to 5500{AA}, were obtained with the Coude Echelle Spectrograph at Beijing Astronomical Observatory on March 26, 28 and April 22, 1997. In the spectra we found 532 emission features, among which 459 lines from H, O, Na, C_2_, C_3_, CN, CH, NH_2_ and H_2_O^+^ were identified. The intensity of sodium emission lines at 5890 {AA} and 5896 {AA} on April 22 increased about 5 fold compared to that recorded on March 26 and 28. The intensity ratio I_{lambda}5577_/(I_{lambda}6300_+I_{lambda}6364_) of [O I] is consistent with the formation of excited O atoms from the photodissociation of H_2_O.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A127
- Title:
- Comet C/2016 R2 (PanSTARRS) IRAM spectra
- Short Name:
- J/A+A/619/A127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-wavelength study of comet C/2016 R2 (PanSTARRS). This comet was observed on 23-24 January 2018 with the IRAM 30m telescope, and in January to March 2018 with the Nancay radio telescope. Visible spectroscopy was performed in December 2017 and February 2018 with small amateur telescopes. We report on measurements of CO, CH_3_OH, H_2_CO and HCN production rates, and on the determination of the N2/CO abundance ratio. Several other species, especially OH, were searched for but not detected. The inferred relative abundances, including upper limits for sulfur species, are compared to those measured in other comets at about the same heliocentric distance of ~2.8AU. The coma composition of comet C/2016 R2 is very different from all other comets observed so far, being rich in N2 and CO and dust poor. This suggests that this comet might belong to a very rare group of comets formed beyond the N_2_ ice line. Alternatively, comet C/2016 R2 (PanSTARRS) could be the fragment of a large and differentiated transneptunian object, with properties characteristic of volatile-enriched layers.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A119
- Title:
- Comet 67P/Churyumov-Gerasimenko FUV aurora
- Short Name:
- J/A+A/647/A119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to determine whether dissociative excitation of cometary neutralsby electron impact is the major source of far-ultraviolet (FUV) emissions at comet 67P/Churyumov-Gerasimenkoin the southern hemisphere at large heliocentric distances, both during quiet conditions and impacts of corotating interaction regions observed in the summer of 2016. We combined multiple datasets from the Rosetta mission through a multi-instrument analysis to complete the first forward modelling of FUV emissions in the southern hemisphere of comet 67P and compared modelled brightnesses to observations with the Alice FUV imaging spectrograph. We modelled the brightness of OI1356, OI1304, Lyman-beta, CI1657, and CII1335 emissions, which are associated with the dissociation products of the four major neutral species in the coma: CO2, H2O, CO, and O2. The suprathermal electron population was probed by the Ion and Electron Sensor of theRosetta Plasma Consortium (RPC/IES) and the neutral column density was constrained by several instruments: the RosettaOrbiter Spectrometer for Ion and Neutral Analysis (ROSINA), the Microwave Instrument for the Rosetta Orbiter (MIRO)and the Visual InfraRed Thermal Imaging Spectrometer (VIRTIS). The modelled and observed brightnesses of the FUV emission lines agree closely when viewing nadir and dissociative excitation by electron impact is shown to be the dominant source of emissions away from perihelion. The CII1335 emissions are shown to be consistent with the volume mixing ratio of CO derived from ROSINA. When viewing the limb during the impacts of corotating interaction regions, the model reproduces brightnesses of OI1356 and CI1657 well, but resonance scattering in the extended coma may contribute significantly to the observed Lyman-beta and OI1304 emissions. The correlation between variations in the suprathermal electron flux and the observed FUV line brightnesses when viewing the comet's limb suggests electrons are accelerated on large scales and that they originate in the solar wind. This means that the FUV emissions are auroral in nature.
- ID:
- ivo://CDS.VizieR/J/A+A/461/789
- Title:
- Comet 153P/Ikeya-Zhang emission lines catalog
- Short Name:
- J/A+A/461/789
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A program of high resolution spectroscopy of comets is being conducted at TNG (Canary Islands) using the echelle spectrograph SARG. The aim of the program is to catalogue emission lines in the visible range of various comets, compare them and possibly identify the many existing unknown lines. As a first step, we catalogued the lines in the spectrum of the comet 153P/Ikeya-Zhang and compared them with the lines already listed in existing catalogues. The comet was observed with SARG on the night 19-20 of April, 2002, with a short slit covering the spectral range of 4620-7920{AA} and with a resolving power R=57000, finding 8468 emission lines.
- ID:
- ivo://CDS.VizieR/J/ApJS/225/23
- Title:
- Compact groups of galaxies from SDSS-DR12 (MLCG)
- Short Name:
- J/ApJS/225/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We apply a friends-of-friends algorithm to an enhanced SDSS DR12 spectroscopic catalog, including redshift from the literature to construct a catalog of 1588 N>=3 compact groups of galaxies containing 5178 member galaxies and covering the redshift range 0.01<z<0.19. This catalog contains 18 times as many systems and reaches 3 times the depth of the similar catalog of Barton et al. (1996AJ....112..871B). We construct catalogs from both magnitude-limited and volume-limited galaxy samples. Like Barton et al. we omit the frequently applied isolation criterion in the compact group selection algorithm. Thus the groups selected by fixed projected spatial and rest-frame line-of-sight velocity separation produce a catalog of groups with a redshift-independent median size. In contrast to previous catalogs, the enhanced SDSS DR12 catalog (including galaxies with r<14.5) includes many systems with z<~0.05. The volume-limited samples are unique to this study. The compact group candidates in these samples have a median stellar mass independent of redshift. Groups with velocity dispersion <~100km/s show abundant evidence for ongoing dynamical interactions among the members. The number density of the volume-limited catalogs agrees with previous catalogs at the lowest redshifts but decreases as the redshift increases. The SDSS fiber placement constraints limit the catalog's completeness. In spite of this issue, the volume-limited catalogs provide a promising basis for detailed spatially resolved probes of the impact of galaxy-galaxy interactions within similar dense systems over a broad redshift range.
- ID:
- ivo://CDS.VizieR/J/ApJS/246/12
- Title:
- Compact groups of galaxies in SDSS & LAMOST. I.
- Short Name:
- J/ApJS/246/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A compact group (CG) is a kind of special galaxy system where the galaxy members are separated at distances of the order of galaxy size. The strong interaction between the galaxy members makes CGs ideal labs for studying the environmental effects on galaxy evolution. The traditional photometric selection algorithm biases against the CG candidates at low redshifts, while the spectroscopic identification technique is affected by the spectroscopic incompleteness of sample galaxies and typically biases against the high redshift candidates. In this study, we combine these two methods and select CGs in the main galaxy sample of the Sloan Digital Sky Survey, where we also have taken the advantages of the complementary redshift measurements from the LAMOST spectral and GAMA surveys. We have obtained the largest and most complete CG samples to date. Our samples include 6144 CGs and 8022 CG candidates, which are unique in the studies of the nature of the CGs and the evolution of the galaxies inside.
- ID:
- ivo://CDS.VizieR/J/ApJ/792/119
- Title:
- Companions to nearby stars from Pan-STARRS 1
- Short Name:
- J/ApJ/792/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of 57 wide (>5'') separation, low-mass (stellar and substellar) companions to stars in the solar neighborhood identified from Pan-STARRS 1 (PS1) data and the spectral classification of 31 previously known companions. Our companions represent a selective subsample of promising candidates and span a range in spectral type of K7-L9 with the addition of one DA white dwarf. These were identified primarily from a dedicated common proper motion search around nearby stars, along with a few as serendipitous discoveries from our Pan-STARRS 1 brown dwarf search. Our discoveries include 23 new L dwarf companions and one known L dwarf not previously identified as a companion. The primary stars around which we searched for companions come from a list of bright stars with well-measured parallaxes and large proper motions from the Hipparcos catalog (8583 stars, mostly A-K dwarfs) and fainter stars from other proper motion catalogs (79170 stars, mostly M dwarfs). We examine the likelihood that our companions are chance alignments between unrelated stars and conclude that this is unlikely for the majority of the objects that we have followed-up spectroscopically. We also examine the entire population of ultracool (>M7) dwarf companions and conclude that while some are loosely bound, most are unlikely to be disrupted over the course of ~10 Gyr. Our search increases the number of ultracool M dwarf companions wider than 300 AU by 88% and increases the number of L dwarf companions in the same separation range by 82%. Finally, we resolve our new L dwarf companion to HIP 6407 into a tight (0.13'', 7.4 AU) L1+T3 binary, making the system a hierarchical triple. Our search for these key benchmarks against which brown dwarf and exoplanet atmosphere models are tested has yielded the largest number of discoveries to date.
- ID:
- ivo://CDS.VizieR/J/A+A/547/A108
- Title:
- Comparative modelling of cool giants spectra
- Short Name:
- J/A+A/547/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our ability to extract information from the spectra of stars depends on reliable models of stellar atmospheres and appropriate techniques for spectral synthesis. The corresponding paper aims to compare a wide variety of model codes and strategies for the analysis of stellar spectra that are available today. The online tables list spectral lines used during the analysis together with the basic line parameters.
- ID:
- ivo://CDS.VizieR/J/AJ/155/162
- Title:
- Comparison of IUE and CALSPEC SEDs for 6 WDs
- Short Name:
- J/AJ/155/162
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A collection of spectral energy distributions (SEDs) is available in the Hubble Space Telescope (HST) CALSPEC database that is based on calculated model atmospheres for pure hydrogen white dwarfs (WDs). A much larger set (~100000) of UV SEDs covering the range (1150-3350 {AA}) with somewhat lower quality are available in the IUE database. IUE low-dispersion flux distributions are compared with CALSPEC to provide a correction that places IUE fluxes on the CALSPEC scale. While IUE observations are repeatable to only 4%-10% in regions of good sensitivity, the average flux corrections have a precision of 2%-3%. Our re-calibration places the IUE flux scale on the current UV reference standard and is relevant for any project based on IUE archival data, including our planned comparison of GALEX to the corrected IUE fluxes. IUE SEDs may be used to plan observations and cross-calibrate data from future missions, so the IUE flux calibration must be consistent with HST instrumental calibrations to the best possible precision.
