- ID:
- ivo://CDS.VizieR/J/other/AstBu/71.302
- Title:
- CP stars magnetic fields catalog (2009)
- Short Name:
- J/other/AstBu/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of measuring longitudinal magnetic fields (B_e), rotation velocities (v_e_sini), and radial velocities (V_r_) of 44 stars observed with the Main Stellar Spectrograph (MSS) of the 6-m BTA telescope of the Special Astrophysical Observatory in 2009. Observations of standard stars without magnetic fields confirm the absence of systematic errors capable of introducing distortions into the longitudinal-field measurement results. In this work we comment on the results for each of the stars.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/other/AstBu/69.427
- Title:
- CP stars magnetic fields catalog (2007)
- Short Name:
- J/other/AstBu/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog presents the results of magnetic field measurements for 39 chemically peculiar and 3 normal main sequence stars used as standard stars. Observations were carried out with the Main Stellar Spectrograph of the Russian 6-m telescope during 2007. The accuracy analysis for the longitudinal magnetic field measurements of the stars confirms that the systematic errors do not exceed 10-20G and are within the quoted limits. The absence of significant instrumental deviations follows from the measurements of theBD CP stars with well-known B_e_ variation curves.
- ID:
- ivo://CDS.VizieR/J/other/AstBu/70.444
- Title:
- CP stars magnetic fields catalog (2008)
- Short Name:
- J/other/AstBu/70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the magnetic field measurements of 37 chemically peculiar and 4 normal main sequence stars using circularly polarized spectra obtained in 2008 with a Zeeman analyzer on the Main Stellar Spectrograph (MSS) of the Russian 6-m telescope (BTA). Four new magnetic stars have been discovered (HD25999, HD35100, HD96237, and HD279021), the presence of a field was suspected in two stars (HD2887 and BD-12 2366), 16 previously known CP stars were continued to be monitored to study their fields. The results of the longitudinal magnetic field B_e_ measurements show that in stars with narrow spectral lines, systematic errors in B_e_ determination do not exceed 10-20G, which is within the statistical error. Our study of stars with reliable phase curves of the longitudinal field B_e_ show that there are no instrumental effects which can distort the observations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/1763
- Title:
- Detectability of radio emission from exoplanets
- Short Name:
- J/MNRAS/478/1763
- Date:
- 19 Jan 2022 00:23:37
- Publisher:
- CDS
- Description:
- Like the magnetized planets in our Solar system, magnetized exoplanets should emit strongly at radio wavelengths. Radio emission directly traces the planetary magnetic fields and radio detections can place constraints on the physical parameters of these features. Large comparative studies of predicted radio emission characteristics for the known population of exoplanets help to identify what physical parameters could be the key for producing bright, observable radio emission. Since the last comparative study, many thousands of exoplanets have been discovered. We report new estimates for the radio flux densities and maximum emission frequencies for the current population of known exoplanets orbiting pre-main-sequence and main-sequence stars with spectral types F-M. The set of exoplanets predicted to produce observable radio emission are Hot Jupiters orbiting young stars. The youth of these systems predicts strong stellar magnetic fields and/or dense winds, which are the key for producing bright, observable radio emission. We use a new all-sky circular polarization Murchison Widefield Array survey to place sensitive limits on 200MHz emission from exoplanets, with 3{sigma} values ranging from 4.0 to 45.0mJy. Using a targeted Giant Metrewave Radio Telescope observing campaign, we also report a 3{sigma} upper limit of 4.5mJy on the radio emission from V830 Tau b, the first Hot Jupiter to be discovered orbiting a pre-main-sequence star. Our limit is the first to be reported for the low-frequency radio emission from this source.
- ID:
- ivo://CDS.VizieR/J/A+A/450/763
- Title:
- Evolutionary state of magnetic CP stars
- Short Name:
- J/A+A/450/763
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The photospheres of about 5-10% of the upper main sequence stars exhibit remarkable chemical anomalies. Many of these chemically peculiar (CP) stars have a global magnetic field, the origin of which is still a matter of debate. We present a comprehensive statistical investigation of the evolution of magnetic CP stars, aimed at providing constraints to the theories that deal with the origin of the magnetic field in these stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/74
- Title:
- Excited-state hydroxyl maser polarimetry
- Short Name:
- J/MNRAS/451/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present polarimetric maser observations with the Australia Telescope Compact Array of excited-state hydroxyl (OH) masers. We observed 30 fields of OH masers in full Stokes polarization with the Compact Array Broadband Backend at both the 6030 and 6035 MHz excited-state OH transitions, and the 6668 MHz methanol maser transition, detecting 70 sites of maser emission. Amongst the OH we found 112 Zeeman pairs, of which 18 exhibited candidate {pi} components. This is the largest single full polarimetric study of multiple sites of star formation for these frequencies, and the rate of 16 percent {pi} components clearly indicates that the {pi} component exists, and is comparable to the percentage recently found for ground-state transitions. This significant percentage of {pi} components, with consistent proportions at both ground- and excited-state transitions, argues against Faraday rotation suppressing the {pi} component emission. Our simultaneous observations of methanol found the expected low level of polarization, with no circular detected, and linear only found at the =<10 percent level for the brightest sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/411/L46
- Title:
- Exoplanet magnetic fields
- Short Name:
- J/MNRAS/411/L46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An asymmetry between the ingress and egress times was observed in the near-UV light curve of the transit planet WASP-12b. Such asymmetry led us to suggest that the early ingress in the UV light curve of WASP-12b, compared to the optical observations, is caused by a shock around the planet, and that shocks should be a common feature in transiting systems. Here, we classify all the transiting systems known to date according to their potential for producing shocks that could cause observable light curve asymmetries.
- ID:
- ivo://CDS.VizieR/J/ApJ/612/511
- Title:
- Exoplanet radio emission
- Short Name:
- J/ApJ/612/511
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We predict the radio flux densities of the extrasolar planets in the current census, making use of an empirical relation - the radiometric Bode's law - determined from the five "magnetic" planets in the solar system (the Earth and the four gas giants). Radio emission from these planets results from solar wind-powered electron currents depositing energy in the magnetic polar regions. We find that most of the known extrasolar planets should emit in the frequency range 10-1000 MHz and, under favorable circumstances, have typical flux densities as large as 1mJy. We also describe an initial, systematic effort to search for radio emission in low radio frequency images acquired with the Very Large Array (VLA). The limits set by the VLA images (~300mJy) are consistent with, but do not provide strong constraints on, the predictions of the model.
- ID:
- ivo://CDS.VizieR/J/ApJ/714/1170
- Title:
- Faraday rotation at high Galactic latitude
- Short Name:
- J/ApJ/714/1170
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the vertical magnetic field of the Milky Way toward the Galactic poles, determined from observations of Faraday rotation toward more than 1000 polarized extragalactic radio sources at Galactic latitudes |b|>=77{deg}, using the Westerbork Radio Synthesis Telescope and the Australia Telescope Compact Array. We find median rotation measures (RMs) of 0.0+/-0.5rad/m^2^ and +6.3+/-0.7rad/m^2^ toward the north and south Galactic poles, respectively, demonstrating that there is no coherent vertical magnetic field in the Milky Way at the Sun's position. If this is a global property of the Milky Way's magnetism, then the lack of symmetry across the disk rules out pure dipole or quadrupole geometries for the Galactic magnetic field. The angular fluctuations in RM seen in our data show no preferred scale within the range ~0.1{deg} to ~25{deg}. The observed standard deviation in RM of ~9rad/m^2^ then implies an upper limit of ~1uG on the strength of the random magnetic field in the warm ionized medium at high Galactic latitudes.
- ID:
- ivo://CDS.VizieR/J/ApJ/795/63
- Title:
- Faraday rotation from magnesium II absorbers
- Short Name:
- J/ApJ/795/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Strong singly ionized magnesium (Mg II) absorption lines in quasar spectra typically serve as a proxy for intervening galaxies along the line of sight. Previous studies have found a correlation between the number of these Mg II absorbers and the Faraday rotation measure (RM) at ~5 GHz. We cross-match a sample of 35752 optically identified non-intrinsic Mg II absorption systems with 25649 polarized background radio sources for which we have measurements of both the spectral index and RM at 1.4 GHz. We use the spectral index to split the resulting sample of 599 sources into flat-spectrum and steep-spectrum subsamples. We find that our flat-spectrum sample shows significant (~3.5{sigma}) evidence for a correlation between Mg II absorption and RM at 1.4 GHz, while our steep-spectrum sample shows no such correlation. We argue that such an effect cannot be explained by either luminosity or other observational effects, by evolution in another confounding variable, by wavelength-dependent polarization structure in an active galactic nucleus, by the Galactic foreground, by cosmological expansion, or by partial coverage models. We conclude that our data are most consistent with intervenors directly contributing to the Faraday rotation along the line of sight, and that the intervening systems must therefore have coherent magnetic fields of substantial strength (B{bar}=1.8+/-0.4{mu}G). Nevertheless, the weak nature of the correlation will require future high-resolution and broadband radio observations in order to place it on a much firmer statistical footing.
