- ID:
- ivo://CDS.VizieR/J/MNRAS/430/3445
- Title:
- Covering factor of warm dust in quasars
- Short Name:
- J/MNRAS/430/3445
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By combining newly obtained infrared photometric data from the All-Sky Data Release of the Wide-field Infrared Survey Explorer with spectroscopic data from the Seventh Data Release of the Sloan Digital Sky Survey, we study the covering factor of warm dust (CFWD) for a large quasar sample, as well as the relations between CFWD and other physical parameters of quasars. We find a strong correlation between the flux ratio in the mid-infrared to near-ultraviolet and the slope of the near-ultraviolet spectra, which is interpreted as a dust extinction effect. After correcting for dust extinction utilizing the above correlation, we examine the relations between CFWD and active galactic nucleus properties: bolometric luminosity (L_bol_), black hole mass (M_BH_) and Eddington ratio (L/L_Edd_). We confirm the anticorrelation between CFWD and L_bol_. Further, we find that CFWD is anticorrelated with M_BH_ but is independent of L/L_Edd_. Radio-loud quasars are found to follow the same correlations as radio-quiet quasars. Monte Carlo simulations show that the anisotropy of the UV-optical continuum of the accretion disc can have a significant effect, but is not likely to dominate the CFWD-L_bol_ correlation.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/651/A74
- Title:
- 4C +29.45 OVRO and KNV fluxes curve
- Short Name:
- J/A+A/651/A74
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the results of multi-epoch, multifrequency monitoring of blazar 4C +29.45, which was regularly monitored as part of the Interferometric Monitoring of GAmma-ray Bright Active Galactic Nuclei (iMOGABA) program - a key science program of the Korean Very long baseline interferometry Network (KVN). Observations were conducted simultaneously at 22, 43, 86, and 129GHz over the 4 years from 5 December 2012 to 28 December 2016. We also used additional data from the 15GHz Owens Valley Radio Observatory (OVRO) monitoring program. From the 15GHz light curve, we estimated the variability timescales of the source during several radio flux enhancements. We found that the source experienced six radio flux enhancements with variability timescales of 9-187days during the observing period, yielding corresponding variability Doppler factors of 9-27. From the simultaneous multifrequency KVN observations, we were able to obtain accurate radio spectra of the source and hence to more precisely measure the turnover frequencies {nu}_r_, of synchrotron self-absorption (SSA) emission with a mean value of {nu}_r_=28.9GHz. Using jet geometry assumptions, we estimated the size of the emitting region at the turnover frequency. We found that the equipartition magnetic field strength is up to two orders of magnitude higher than the SSA magnetic field strength (0.001-0.1G). This is consistent with the source being particle dominated. We performed a careful analysis of the systematic errors related to the making of these estimations. From the results, we concluded that the equipartition region is located upstream from the SSA region.
- ID:
- ivo://CDS.VizieR/J/ApJ/725/2349
- Title:
- C/O vs Mg/Si of planetary systems
- Short Name:
- J/ApJ/725/2349
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Theoretical studies suggest that C/O and Mg/Si are the most important elemental ratios in determining the mineralogy of terrestrial planets. The C/O ratio controls the distribution of Si among carbide and oxide species, while Mg/Si gives information about the silicate mineralogy. We present a detailed and uniform study of C, O, Mg, and Si abundances for 61 stars with detected planets and 270 stars without detected planets from the homogeneous high-quality unbiased HARPS GTO sample, together with 39 more planet-host stars from other surveys. We determine these important mineralogical ratios and investigate the nature of the possible terrestrial planets that could have formed in those planetary systems. We find mineralogical ratios quite different from those of the Sun, showing that there is a wide variety of planetary systems which are not similar to our solar system. Many planetary host stars present an Mg/Si value lower than 1, so their planets will have a high Si content to form species such as MgSiO_3_. This type of composition can have important implications for planetary processes such as plate tectonics, atmospheric composition, or volcanism.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A84
- Title:
- C/O vs Mg/Si ratios in solar type stars
- Short Name:
- J/A+A/614/A84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to present a detailed study of the magnesium-to-silicon and carbon-to-oxygen ratios (Mg/Si and C/O) and their importance in determining the mineralogy of planetary companions. Using 499 solar-like stars from the HARPS sample, we determined C/O and Mg/Si elemental abundance ratios to study the nature of the possible planets formed. We separated the planetary population in low-mass planets (<30M_{sun}_) and high-mass planets (>30M_{sun}_) to test for a possible relation with the mass. We find a diversity of mineralogical ratios that reveal the different kinds of planetary systems that can be formed, most of them dissimilar to our solar system. The different values of the Mg/Si and C/O can determine different composition of planets formed. {We found that 100% of our planetary sample present C/O<0.8. 86% of stars with high-mass companions present 0.8>C/O>0.4, while 14% present C/O values lower than 0.4. Regarding Mg/Si, all stars with low-mass planetary companion showed values between one and two, while 85% of the high-mass companion sample does. The other 15% showed Mg/Si values below one. No stars with planets were found with Mg/Si>2. Planet hosts with low-mass companions present C/O and Mg/Si similar to those found in the Sun, whereas stars with high-mass companions have lower C/O.
4025. COYOTES II
- ID:
- ivo://CDS.VizieR/J/A+A/299/89
- Title:
- COYOTES II
- Short Name:
- J/A+A/299/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
4026. CPASJ2 catalogue
- ID:
- ivo://CDS.VizieR/J/A+AS/136/1
- Title:
- CPASJ2 catalogue
- Short Name:
- J/A+AS/136/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- According to the cooperation between Beijing, San Juan and La Plata Astronomical Observatories, the photoelectric astrolabe Mark II(PAII) of the Beijing Astronomical Observatory was moved and installed at the San Juan Observatory, Argentina in January, 1992 for observations of the catalogue of stars in the southern hemisphere. The first observing period was from Feb. 23, 1992 to Mar. 31, 1997. Using the data observed in San Juan with the instrument during this period, residuals for 11002 stars are reduced from about 405700 observations of stars over 1532 days. The mean precision of the residuals is +/-0.043". The Second Catalogue of Stars (CPASJ2) has been compiled from double transits at both the eastern and western passages. There are 5241 stars in this catalogue, including 1225 FK5/FK4Supp stars, 794 FK5Ext stars, 1084 SRS stars, 937 CAMC4 stars, 310 GC stars and 891 IMF stars. The mean precisions are +/-3.2ms and +/-0.057" in right ascension and declination, respectively. The magnitudes of stars are from 2.0 to 11.5. The declinations are from -3{deg} to -60{deg}. The mean epoch is 1994.9. Finally, systematic corrections of(CPASJ2-FK5) are given.
4027. CPASJ1 catalogue
- ID:
- ivo://CDS.VizieR/J/A+AS/118/1
- Title:
- CPASJ1 catalogue
- Short Name:
- J/A+AS/118/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On the basis of the data observed with the photoelectric astrolabe Mark II(PA II) of Beijing Astronomical Observatory in San Juan of Argentina from Feb. 23, 1992 to Feb. 28, 1995, residuals of 7200 stars are reduced according to about 230000 observations of stars. The mean precision of the residuals is +/-0.046". Using the data, the first catalogue of stars (CPASJ1) have been compiled. There are 2980 stars in this catalogue included 989 FK5/FK4Supp stars, 658 FK5Ext stars, 387 SRS stars, 687 CAMC4 stars, 192 GC stars, and 72 Hipparcos stars. The mean precisions are +/-3.2ms and +/-0.061" in right ascensions and declinations, respectively. The magnitudes of stars are from 2mag to 11.3mag. The declinations are from -3deg to -60deg. The mean epoch is 1993.6. Finally, systematic corrections of(CPASJ1-FK5) are given.
4028. CPASJ3 catalogue
- ID:
- ivo://CDS.VizieR/J/A+A/430/327
- Title:
- CPASJ3 catalogue
- Short Name:
- J/A+A/430/327
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Resulting from the cooperation between Beijing, San Juan and La Plata Astronomical Observatories, the photoelectric astrolabe Mark II(PAII) of the Beijing Astronomical Observatory was moved and installed at the San Juan Observatory, Argentina in January, 1992 for observations of stars in the southern hemisphere. Using the data observed with the instrument from Feb. 23 1992 to Mar. 11, 2000 over 2382 days, the Third San Juan photoelectric astrolabe catalogue has been compiled from double transits at both the eastern and western passages. There are 6762 stars in this catalogue, including 6156 Hipparcos stars (in which there are 69 radio stars), 8 FK5 stars, 47 SRS stars, 551 CAMC4 stars. The mean precisions are +/-3.0ms and +/-0.053"' in right ascension and declination, respectively. The magnitudes of stars are from 1.0 to 11.5. The declinations are from -3{deg} to -60{deg}. The mean epoch is 1996.3. Systematic corrections of (CPASJ3-Hipp) are given.
- ID:
- ivo://CDS.VizieR/J/other/PBeiO/24.71
- Title:
- CPASJ1 position corrections
- Short Name:
- J/other/PBeiO/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the data observed with the Photoelectric Astrolabe Mark II (PA II) of the Beijing Astronomical Observatory during the period from Feb. 1992 to Oct. 1993 in San Juan of Argentina, the first catalogue of stars (PASJ1, Cat. <J/A+AS/118/1>) have been compiled. It consists of 1400 stars included 682 FK5/FK4 Supp stars. 433 FK5 Ext stars and 285 CAMC stars (1, 1989). The mean precisions of delta alpha's and delta delta's are +/-3.2ms and 0.055", respectively. The mean epoch is 1992.9. Finally, systematic corrections of (PASJ1-FK5) are given.
- ID:
- ivo://CDS.VizieR/J/A+A/310/893
- Title:
- C_2_ Phillips and CN Red bands in HD 56126
- Short Name:
- J/A+A/310/893
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the detection of molecular absorption lines in the optical spectrum of the post-AGB star HD 56126. The C_2_ Phillips A^1^{PI}_u_-X^1^{SIGMA}^+^_g_(1,0), (2,0), and (3,0); Swan d^3^{PI}_g_-a^3^{PI}_u_(0,0) and (1,0); and CN Red system A^2^{PI}-X^2^{SIGMA}^+^ (1,0), (2,0), (3,0), and (4,0) bands have been identified. From the identification of the molecular bands we find an expansion velocity of 8.5+/-0.6km/s independent of excitation condition or molecular specie. On the basis of the expansion velocity, rotational temperatures, and molecular column densities we argue that the line-forming region is the AGB remnant. This is in agreement with the expansion velocity derived from the CO lines. We find column densities of logN_C_2__=15.3+/-0.3cm^-2^ and logN_CN_=15.5+/-0.3cm^-2^, and rotational temperatures of T_rot_=242+/-20K and T_rot_=24+/-5K respectively for C_2_ and CN. By studying molecular line absorption in optical spectra of post-AGB stars we have found a new tracer of the AGB remnant. From comparison with the results of CO and IR observations it is possible to obtain information on non-spherical behavior of the AGB remnant. Using different molecules with different excitation conditions it should be possible to study the AGB remnant as a function of the distance to the star, and thus as a function of the evolutionary status of the star on the AGB.