- ID:
- ivo://CDS.VizieR/J/AJ/152/111
- Title:
- A 2011-2013 survey of trans-Neptunian objects
- Short Name:
- J/AJ/152/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The trans-Neptunian objects (TNOs) preserve evidence of planet building processes in their orbital and size distributions. While all populations show steep size distributions for large objects, a relative deficit of Neptunian trojans and scattering objects with diameters of D<100km has been detected. We investigated this deficit with a 32 square degree survey, in which we detected 77 TNOs that are brighter than a limiting r-band magnitude of 24.6. Our plutino sample (18 objects in 3:2 mean-motion resonance with Neptune) shows a deficit of D<100km objects, rejecting a single power-law size distribution at >99% confidence. Combining our survey with the Canada-France Ecliptic Plane Survey, we perform a detailed analysis of the allowable parameters for the plutino size distribution, including knees and divots. We surmise the existence of 9000+/-3000 plutinos with an absolute magnitude of H_r_{<=}8.66 and 37000_-10000_^+12000^ with H_r_{<=}10.0 (95% confidence). Our survey also discovered one temporary Uranian trojan, one temporary Neptunian trojan, and one stable Neptunian trojan, for which we estimate populations of 110_-100_^+500^, 210_-200_^+900^, and 150_-140_^+600^ with H_r_{<=}10.0, respectively. All three populations are thus less numerous than the main belt asteroids (592 asteroids with H_r_{<=}10.0). With such population sizes, the temporary Neptunian trojans cannot be previously stable trojans diffusing out of the resonance now; they must be recently captured Centaurs or scattering objects. As the bias against the detection of objects grows with larger semimajor axes, our discovery of three 3:1 resonators and one 4:1 resonator adds to the growing evidence that the high-order resonances are far more populated than is typically predicted.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/127/1567
- Title:
- Asymmetric thick disk. II. Kinematics
- Short Name:
- J/AJ/127/1567
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a kinematic signature associated with the observed asymmetry in the distribution of thick-disk/inner halo stars interior to the solar circle described in Paper I (Parker et al., 2003AJ....126.1346P). In that paper, we found a statistically significant excess (20%-25%) of stars in quadrant I (l~20{deg}-55{deg}) both above and below the plane (b~+/-25{deg} to b~+/-45{deg}) compared with the complementary region in quadrant IV. We have measured Doppler velocities for 741 stars, selected according to the same magnitude and color criteria, in the direction of the asymmetry and in the corresponding fields in quadrant IV. We have also determined spectral types and metallicities measured from the same spectra.
- ID:
- ivo://CDS.VizieR/J/A+A/281/15
- Title:
- Asymmetries in radio source structures
- Short Name:
- J/A+A/281/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/274/555
- Title:
- Asymmetry of FeI lines in solar spectrum
- Short Name:
- J/A+A/274/555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 75 FeI lines were studied from wide slit FTS spectra obtained at Kitt Peak at the center of the disk, near the limb ({mu}=0.2)
- ID:
- ivo://CDS.VizieR/J/ApJ/857/119
- Title:
- Asymmetry of oscillations in 43 Kepler stars
- Short Name:
- J/ApJ/857/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Oscillation properties are usually measured by fitting symmetric Lorentzian profiles to the power spectra of Sun-like stars. However, the line profiles of solar oscillations have been observed to be asymmetrical for the Sun. The physical origin of this line asymmetry is not fully understood; though, it should depend on the depth dependence of the source of wave excitation (convective turbulence) and details of the observable (velocity or intensity). For oscillations of the Sun, it has been shown that neglecting the asymmetry leads to systematic errors in the frequency determination. This could subsequently affect the results of seismic inferences of the solar internal structure. Using light curves from the Kepler spacecraft, we have measured mode asymmetries in 43 stars. We confirm that neglecting the asymmetry leads to systematic errors that can exceed the 1{sigma} confidence intervals for seismic observations longer than one year. Therefore, the application of an asymmetric Lorentzian profile should be favored to improve the accuracy of the internal stellar structure and stellar fundamental parameters. We also show that the asymmetry changes sign between cool Sun-like stars and hotter stars. This provides the best constraints to date on the location of the excitation sources across the Hertzsprung-Russel diagram.
- ID:
- ivo://CDS.VizieR/J/A+A/637/A20
- Title:
- AT 2019abn: multi-wavelength observations
- Short Name:
- J/A+A/637/A20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AT 2019abn was discovered in the nearby M51 galaxy by the Zwicky Transient Facility at more than two magnitudes and around three weeks prior to its optical peak. We aim to conduct a detailed photometric and spectroscopic follow-up campaign for AT 2019abn, with early discovery allowing for significant pre-maximum observations of an intermediate luminosity red transient (ILRT) for the first time. This work is based on the analysis of u'BVr'i'z'H photometry and low-resolution spectroscopy using the Liverpool Telescope, medium-resolution spectroscopy with the Gran Telescopio Canarias (GTC), and near-infrared imaging with the GTC and the Nordic Optical Telescope. We present the most detailed optical light curve of an ILRT to date, with multi-band photometry starting around three weeks before peak brightness. The transient peaked at an observed absolute magnitude of M_r_=-13.1, although it is subject to significant reddening from dust in M51, implying an intrinsic M_r_~-15.2. The initial light curve showed a linear, achromatic rise in magnitude before becoming bluer at peak. After peak brightness, the transient gradually cooled. This is reflected in our spectra, which at later times show absorption from such species as FeI, NiI and LiI. A spectrum taken around peak brightness shows narrow, low-velocity absorption lines, which we interpret as likely to originate from pre-existing circumstellar material. We conclude that while there are some peculiarities, such as the radius evolution, AT 2019abn fits in well overall with the ILRT class of objects and is the most luminous member of the class seen to date.
1307. AT 2018bwo light curves
- ID:
- ivo://CDS.VizieR/J/A+A/653/A134
- Title:
- AT 2018bwo light curves
- Short Name:
- J/A+A/653/A134
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Luminous red novae (LRNe) are astrophysical transients associated with the partial ejection of a binary system's common envelope (CE) shortly before its merger. Here we present the results of our photometric and spectroscopic follow-up campaign of AT 2018bwo (DLT 18x), a LRN discovered in NGC 45, and investigate its progenitor system using binary stellar-evolution models. The transient reached a peak magnitude of M_r_=-10.97+/-0.11 and maintained this brightness during its optical plateau of t_p_=41+/-5d ays. During this phase, it showed a rather stable photospheric temperature of ~3300K and a luminosity of ~10^40^erg/s. Although the luminosity and duration of AT 2018bwo is comparable to the LRNe V838 Mon and M31-2015LRN, its photosphere at early times appears larger and cooler, likely due to an extended mass-loss episode before the merger. Toward the end of the plateau, optical spectra showed a reddened continuum with strong molecular absorption bands. The IR spectrum at +103 days after discovery was comparable to that of an M8.5 II type star, analogous to an extended AGB star. The reprocessed emission by the cooling dust was also detected in the mid-infrared bands ~1.5 years after the outburst. Archival Spitzer and Hubble Space Telescope data taken 10-14yrs before the transient event suggest a progenitor star with T_prog_~6500K, R_prog_~100R_{sun}_, and L_prog_=2x10^4^L_{sun}_, and an upper limit for optically thin warm (1000K) dust mass of M_d_<10^-6^M_{sun}_. Using stellar binary-evolution models, we determined the properties of binary systems consistent with the progenitor parameter space. For AT 2018bwo, we infer a primary mass of 12-16M_{sun}_, which is 9-45% larger than the ~11M_{sun}_ obtained using single-star evolution models. The system, consistent with a yellow-supergiant primary, was likely in a stable mass-transfer regime with -2.4 <= log (M_dot/Msun /yr) <= -1.2 a decade before the main instability occurred. During the dynamical merger, the system would have ejected 0.15-0.5M_{sun}_ with a velocity of ~500km/s.
- ID:
- ivo://CDS.VizieR/J/A+A/445/465
- Title:
- ATCA 18.5 and 22GHz fluxes of Kuehr 5GHz sample
- Short Name:
- J/A+A/445/465
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss our ATCA 18.5 and 22GHz flux density measurements of Southern extragalactic sources in the complete 5GHz sample of Kuehr et al. (1981, Cat. <VIII/5>). The high frequency (5-18.5GHz) spectral indices of steep-spectrum sources for which we have 18.5GHz data (66% of the complete sample) are systematically steeper than the low frequency (2.7-5GHz) ones, and there is evidence of an anti-correlation of high-frequency spectral index with luminosity. The completeness of 18.5GHz data is much higher (89%) for flat-spectrum sources (mostly quasars), which also exhibit a spectral steepening. Taking advantage of the almost complete redshift information on flat-spectrum quasars, we have estimated their 5GHz luminosity function in several redshift bins. The results confirm that their radio luminosity density peaks at z_peak about 2.5 but do not provide evidence for deviations from pure luminosity evolution as hinted at by other data sets. A comparison of our 22GHz flux densities with WMAP K-band data for flat-spectrum sources suggests that WMAP flux densities may be low by a median factor of about 1.2. The extrapolations of 5GHz counts and luminosity functions of flat-spectrum radio quasars using the observed distribution of the 5-18.5GHz spectral indices match those derived directly from WMAP data, indicating that the high frequency WMAP survey does not detect any large population of FSRQs with anomalous spectra.
- ID:
- ivo://CDS.VizieR/J/MNRAS/354/305
- Title:
- ATCA 18GHz pilot survey first results
- Short Name:
- J/MNRAS/354/305
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a pilot study for the first all-sky radio survey at short wavelengths, we have observed 1216deg^2^ of the southern sky at 18GHz (16mm) using a novel wide-band (3.4-GHz bandwidth) analogue correlator on one baseline of the Australia Telescope Compact Array. We scanned a region of sky between declination -71{deg} and -59{deg} with an rms noise level of 15mJy. Follow-up radio imaging of candidate sources above a 4{sigma} detection limit of 60mJy resulted in 221 confirmed detections, for which we have measured accurate positions and flux densities. For extragalactic sources, the survey is roughly 70 per cent complete at a flux density of 126mJy and 95 per cent complete above 300mJy. Almost half the detected sources lie within a few degrees of the Galactic plane, but there are 123 sources with |b|>5{deg}, which can be assumed to be extragalactic.
- ID:
- ivo://CDS.VizieR/J/ApJS/244/7
- Title:
- ATCA HI absorption survey in Magellanic clouds. I.
- Short Name:
- J/ApJS/244/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from the Small Magellanic Cloud portion of a new Australia Telescope Compact Array HI absorption survey of both of the Magellanic Clouds, comprising over 800hr of observations. Our new HI absorption line data allow us to measure the temperature and fraction of cold neutral gas in a low-metallicity environment. We observed 22 separate fields, targeting a total of 55 continuum sources, against 37 of which we detected HI absorption; from this we measure a column-density-weighted mean average spin temperature of <Ts>=150K. Splitting the spectra into individual absorption line features, we estimate the temperatures of different gas components and find an average cold gas temperature of ~30K for this sample, lower than the average of ~40K in the Milky Way. The HI appears to be evenly distributed throughout the SMC, and we detect absorption in 67% of the lines of sight in our sample, including some outside the main body of the galaxy (N_HI_>2x10^21^cm^-2^). The optical depth and temperature of the cold neutral atomic gas show no strong trend with location spatially or in velocity. Despite the low-metallicity environment, we find an average cold gas fraction of ~20%, not dissimilar from that of the Milky Way.
