scholarly journals Testing the fossil field hypothesis: could strongly magnetised OB stars produce all known magnetars?

2021 ◽  
Author(s):  
Ekaterina I Makarenko ◽  
Andrei P Igoshev ◽  
A F Kholtygin
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Population Synthesis ◽  
Radio Pulsars ◽  
B Stars ◽  
Supernova Explosions ◽  
The Difference ◽  
Log Normal ◽  
Log Normal Distribution ◽  
The Magnetic Field

Abstract Stars of spectral types O and B produce neutron stars (NSs) after supernova explosions. Most of NSs are strongly magnetised including normal radio pulsars with B∝1012 G and magnetars with B∝1014 G. A fraction of 7-12 per cent of massive stars are also magnetised with B∝103 G and some are weakly magnetised with B∝1 G. It was suggested that magnetic fields of NSs could be the fossil remnants of magnetic fields of their progenitors. This work is dedicated to study this hypothesis. First, we gather all modern precise measurements of surface magnetic fields in O, B and A stars. Second, we estimate parameters for log-normal distribution of magnetic fields in B stars and found μB = 2.83 ± 0.1 log10 (G), σB = 0.65 ± 0.09 for strongly magnetised and μB = 0.14 ± 0.5 log10 (G), $\sigma =0.7_{-0.27}^{+0.57}$ for weakly magnetised. Third, we assume that the magnetic field of pulsars and magnetars have 2.7 DEX difference in magnetic fields and magnetars represent 10 per cent of all young NSs and run population synthesis. We found that it is impossible to simultaneously reproduce pulsars and magnetars populations if the difference in their magnetic fields is 2.7 DEX. Therefore, we conclude that the simple fossil origin of the magnetic field is not viable for NSs.

scholarly journals New magnetic field measurements of β Cephei stars and slowly pulsating B stars

2008 ◽  
Vol 4 (S259) ◽  
pp. 389-390
Author(s):  
Swetlana Hubrig ◽  
M. Briquet ◽  
P. De Cat ◽  
M. Schöller ◽  
T. Morel ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Main Sequence ◽  
Field Measurements ◽  
Clear Picture ◽  
Magnetic Survey ◽  
B Stars ◽  
Pulsating Stars ◽  
Magnetic Field Measurements ◽  
The Magnetic Field

AbstractWe present the results of the continuation of our magnetic survey with FORS 1 at the VLT of a sample of B-type stars consisting of confirmed or candidate β Cephei stars and Slowly Pulsating B stars. Roughly one third of the studied β Cephei stars have detected magnetic fields. The fraction of magnetic Slowly Pulsating B and candidate Slowly Pulsating B stars is found to be higher, up to 50%. We find that the domains of magnetic and non-magnetic pulsating stars in the H-R diagram largely overlap, and no clear picture emerges as to the possible evolution of the magnetic field across the main sequence.

Interaction Between Magnetic Fields and Molecular Clouds on the Radio Arc

1990 ◽  
Vol 140 ◽  
pp. 381-381
Author(s):  
M. Tsuboi ◽  
T. Handa+ ◽  
M. Inoue ◽  
J. Inatani ◽  
N. Ukita
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Molecular Clouds ◽  
Galactic Center ◽  
Molecular Structures ◽  
Strong Magnetic Fields ◽  
Radio Observatory ◽  
Center Region ◽  
Supernova Explosions ◽  
The Magnetic Field

We have made observations of the Galactic center region in the CS J=1–0 and J=2–1 lines with the 45-m telescope at Nobeyama Radio Observatory in order to depict the fine structure and the activity of this region. We propose that several expanding molecular structures in this region are originated by successive supernova explosions at least of 102–3 times within 106 years. These may be responsible for strong magnetic fields in the Galactic center region. The interaction between one of the expanding molecular structures and the “vertical” filaments is found. From the appearance of the interaction, the magnetic field in the “vertical” filaments is estimated to be about 3–5 mGauss.

Effects of Low Frequency Magnetic Fields on Chick Embryos. Dependence on Incubation Temperature and Storage of the Eggs

1986 ◽  
Vol 41 (11-12) ◽  
pp. 1111-1116 ◽  
Author(s):  
Jukka P. Juutilainen
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Incubation Temperature ◽  
Low Frequency ◽  
Chick Embryos ◽  
The Difference ◽  
Incubation Temperatures ◽  
And Control ◽  
And Storage ◽  
The Magnetic Field

Abstract Chick embryos were exposed to sinusoidally oscillating 100 Hz magnetic fields during their first two days of development. The magnetic field strength was 1 A/m. Incubation temperatures of 36.3, 37.0, 38.0 and 38.5 °C were used and the duration of the storage of the eggs before incuba­tion was varied from 1 hour to 4 days. After the incubation, the embryos were examined for abnormalities. When the temperature was 36.3 or 37.0 °C and the eggs were stored for one day or less, the effect of the magnetic field was statistically significant. In these conditions, the percent­ age of abnormal control embryos was low, 8% in 36.3 °C and 5% in 37.0 °C. In the exposed groups the corresponding percentages were 23% (36.3 °C) and 25% (37.0 °C). However, higher temperature and storage of the eggs for 3 to 4 days increased the percentage of abnormal embryos in both the exposed and control groups. The difference between the exposed and control embryos was not significant in these conditions. The results demonstrate the importance of the handling of the eggs in this kind of experiments.

scholarly journals High magnetic field pulsars with magnetar-like activity

2012 ◽  
Vol 8 (S291) ◽  
pp. 351-351
Author(s):  
Yuta Aoki
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Thermal Radiation ◽  
High Magnetic Field ◽  
Observational Result ◽  
Radio Pulsars ◽  
X Ray ◽  
S Period ◽  
The Magnetic Field

AbstractTo study the origin of magnetars, a unique opportunity is provided by detecting an excess of X-ray thermal radiation of the radio pulsars (rotation powered pulsars) with dipolar magnetic fields as high as magnetars. The excess is probably caused by decay of the magnetic field as seen in magnetars. In order to investigate whether the rotation powered pulsars have the excess flux and the hard-tail component similar to magnetars, we observed PSR J0726-2612 which has a 3.44 s period and a 3 × 1013 G inferred dipolar magnetic field, with Suzaku for 44 ks on 2011 November 16-17. We report this observational result. We also compare with other observations and discuss a decaying of the magnetic field for normal radio pulsars.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

scholarly journals An 84-μG Magnetic Field in a Galaxy at Z=0.692?

2008 ◽  
Vol 4 (S254) ◽  
pp. 95-96
Author(s):  
Arthur M. Wolfe ◽  
Regina A. Jorgenson ◽  
Timothy Robishaw ◽  
Carl Heiles ◽  
Jason X. Prochaska
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Faraday Rotation ◽  
Large Scale ◽  
Dynamo Model ◽  
Magnetic Field Generation ◽  
Interstellar Gas ◽  
Splitting Technique ◽  
Average Value ◽  
The Magnetic Field

AbstractThe magnetic field pervading our Galaxy is a crucial constituent of the interstellar medium: it mediates the dynamics of interstellar clouds, the energy density of cosmic rays, and the formation of stars (Beck 2005). The field associated with ionized interstellar gas has been determined through observations of pulsars in our Galaxy. Radio-frequency measurements of pulse dispersion and the rotation of the plane of linear polarization, i.e., Faraday rotation, yield an average value B ≈ 3 μG (Han et al. 2006). The possible detection of Faraday rotation of linearly polarized photons emitted by high-redshift quasars (Kronberg et al. 2008) suggests similar magnetic fields are present in foreground galaxies with redshifts z > 1. As Faraday rotation alone, however, determines neither the magnitude nor the redshift of the magnetic field, the strength of galactic magnetic fields at redshifts z > 0 remains uncertain.Here we report a measurement of a magnetic field of B ≈ 84 μG in a galaxy at z =0.692, using the same Zeeman-splitting technique that revealed an average value of B = 6 μG in the neutral interstellar gas of our Galaxy (Heiles et al. 2004). This is unexpected, as the leading theory of magnetic field generation, the mean-field dynamo model, predicts large-scale magnetic fields to be weaker in the past, rather than stronger (Parker 1970).The full text of this paper was published in Nature (Wolfe et al. 2008).

Effect of Magnetic Fields on the Resistance and Microstructure of Al-Cu Alloy during Solidification Processing

2011 ◽  
Vol 287-290 ◽  
pp. 2916-2920
Author(s):  
Chun Yan Ban ◽  
Peng Qian ◽  
Xu Zhang ◽  
Qi Xian Ba ◽  
Jian Zhong Cui
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Turning Points ◽  
Probe Method ◽  
Solidification Processing ◽  
Ac Magnetic Field ◽  
Dc Magnetic Field ◽  
Cu Alloy ◽  
The Difference ◽  
Good Agreement

The resistance of Al-21%Cu alloy under no magnetic field, DC magnetic field and AC magnetic field from liquid to solid was measured by a four-probe method. The difference of resistance versus temperature curves (R-T curves) was analyzed. It is found that the R-T curves of Al-21%Cu alloy are monotone decreasing and have two obvious turning points. Under DC magnetic field, the liquidus and solidus temperatures of the alloy both decrease, while under AC magnetic field, the liquidus and solidus temperatures both increase. There is a good agreement between the microstructure of quenching sample and R-T curves. The mechanism of the effect of magnetic fields was discussed.

Magnetic Field Spectroheliograms from the San Fernando Observatory

1971 ◽  
Vol 43 ◽  
pp. 329-339 ◽  
Author(s):  
Dale Vrabec
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Spiral Structure ◽  
Longitudinal Component ◽  
Solar Telescope ◽  
Solar Magnetic Fields ◽  
San Fernando ◽  
Field Lines ◽  
The Magnetic Field ◽  
Field Network

Zeeman spectroheliograms of photospheric magnetic fields (longitudinal component) in the CaI 6102.7 Å line are being obtained with the new 61-cm vacuum solar telescope and spectroheliograph, using the Leighton technique. The structure of the magnetic field network appears identical to the bright photospheric network visible in the cores of many Fraunhofer lines and in CN spectroheliograms, with the exception that polarities are distinguished. This supports the evolving concept that solar magnetic fields outside of sunspots exist in small concentrations of essentially vertically oriented field, roughly clumped to form a network imbedded in the otherwise field-free photosphere. A timelapse spectroheliogram movie sequence spanning 6 hr revealed changes in the magnetic fields, including a systematic outward streaming of small magnetic knots of both polarities within annular areas surrounding several sunspots. The photospheric magnetic fields and a series of filtergrams taken at various wavelengths in the Hα profile starting in the far wing are intercompared in an effort to demonstrate that the dark strands of arch filament systems (AFS) and fibrils map magnetic field lines in the chromosphere. An example of an active region in which the magnetic fields assume a distinct spiral structure is presented.

scholarly journals No-z Model for Magnetic Fields of Different Astrophysical Objects and Stability of the Solutions

Data ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Evgeny Mikhailov ◽  
Daniela Boneva ◽  
Maria Pashentseva
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Point Of View ◽  
Accretion Discs ◽  
Wide Range ◽  
Astrophysical Objects ◽  
Alpha Effect ◽  
The Stability ◽  
The Magnetic Field

A wide range of astrophysical objects, such as the Sun, galaxies, stars, planets, accretion discs etc., have large-scale magnetic fields. Their generation is often based on the dynamo mechanism, which is connected with joint action of the alpha-effect and differential rotation. They compete with the turbulent diffusion. If the dynamo is intensive enough, the magnetic field grows, else it decays. The magnetic field evolution is described by Steenbeck—Krause—Raedler equations, which are quite difficult to be solved. So, for different objects, specific two-dimensional models are used. As for thin discs (this shape corresponds to galaxies and accretion discs), usually, no-z approximation is used. Some of the partial derivatives are changed by the algebraic expressions, and the solenoidality condition is taken into account as well. The field generation is restricted by the equipartition value and saturates if the field becomes comparable with it. From the point of view of mathematical physics, they can be characterized as stable points of the equations. The field can come to these values monotonously or have oscillations. It depends on the type of the stability of these points, whether it is a node or focus. Here, we study the stability of such points and give examples for astrophysical applications.

scholarly journals First in-orbit results of the vector magnetic field measurement of the High Precision Magnetometer onboard the China Seismo-Electromagnetic Satellite

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Bin Zhou ◽  
Bingjun Cheng ◽  
Xiaochen Gou ◽  
Lei Li ◽  
Yiteng Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Precision ◽  
Magnetic Field Measurement ◽  
Vector Data ◽  
Magnetic Field Data ◽  
Night Side ◽  
The Difference ◽  
The Magnetic Field ◽  
Ground Calibration ◽  
Data Calibration

Abstract The High Precision Magnetometer (HPM) is one of the main payloads onboard the China Seismo-Electromagnetic Satellite (CSES). The HPM consists of two Fluxgate Magnetometers (FGM) and the Coupled Dark State Magnetometer (CDSM), and measures the magnetic field from DC to 15 Hz. The FGMs measure the vector components of the magnetic field; while the CDSM detects the magnitude of the magnetic field with higher accuracy, which can be used to calibrate the linear parameters of the FGM. In this paper, brief descriptions of measurement principles and performances of the HPM, ground, and in-orbit calibration results of the FGMs are presented, including the thermal drift and magnetic interferences from the satellite. The HPM in-orbit vector data calibration includes two steps: sensor non-linearity corrections based on on-ground calibration and fluxgate linear parameter calibration based on the CDSM measurements. The calibration results show a reasonably good stability of the linear parameters over time. The difference between the field magnitude calculated from the calibrated FGM components and the magnitude directly measured by the CDSM is just 0.5 nT (1σ) when the linear parameters are fitted separately for the day- and the night-side. Satellite disturbances have been analyzed including soft and hard remanence as well as magnetization of the magnetic torquer, radiation from the Tri-Band Beacon, and interferences from the rotation of the solar wing. A comparison shows consistency between the HPM and SWARM magnetic field data. Observation examples are introduced in the paper, which show that HPM data can be used to survey the global geomagnetic field and monitor the magnetic field disturbances in the ionosphere.

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