Detection of magnetic field in the B2 star ρ Ophiuchi A with ESO FORS2

Circumstantial evidence suggests that magnetism and enhanced X-ray emission are likely correlated in early B-type stars: similar fractions of them (~10%) are strong and hard X-ray sources and possess strong magnetic fields. It is also known that some B-type stars have spots on their surface. Yet up to now no X-ray activity associated with spots on early-type stars was detected. In this Letter we report the detection of a magnetic field on the B2V star ρ Oph A. Previously, we assessed that the X-ray activity of this star is associated with a surface spot, herewith we establish its magnetic origin. We analyze spectra of ρ Oph A obtained with the FORS2 spectrograph at ESO Very Large Telescope (VLT) at two epochs, and detect a longitudinal component of the magnetic field of the order of ~500 G in one of the datasets. The detection of the magnetic field only at one epoch can be explained by stellar rotation which is also invoked to explain observed periodic X-ray activity. From archival HARPS ESO VLT high resolution spectra we derived the fundamental stellar parameters of ρ Oph A and further constrained its age. We conclude that ρ Oph A provides strong evidence for the presence of active X-ray emitting regions on young magnetized early type stars.

Download Full-text

Radio Detection of Colliding Wind Binaries

Publications of the Astronomical Society of Australia ◽

10.1071/as05039 ◽

2006 ◽

Vol 23 (1) ◽

pp. 50-63 ◽

Cited By ~ 12

Author(s):

Paula Benaglia ◽

Bärbel Koribalski ◽

Juan F. Albacete Colombo

Keyword(s):

Magnetic Field ◽

Thermal Emission ◽

Stellar Systems ◽

Early Type ◽

X Ray ◽

High Energies ◽

Radio Detection ◽

Early Type Stars ◽

The Magnetic Field ◽

Compact Array

AbstractFour massive, early-type stars, three of which are confirmed binaries, have been observed with the Australia Telescope Compact Array at 1.4, 2.4, 4.8, and 8.6 GHz. The earliest star cataloged so far, HD 93129A, was also observed at 17.8 and 24.5 GHz. Here we present an analysis of the spectra as well as the structure of the stellar systems. All four spectra show clear evidence of non-thermal emission, indicative of a binary system with a colliding wind region. We discuss the magnetic field of the emitting region of HD 93129A and make predictions on the radiation at high energies. Archive X-ray observations towards the target sources are also investigated and interpreted in the light of the non-thermal emission detected.

Download Full-text

X-ray diagnostics of massive star winds

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317002952 ◽

2016 ◽

Vol 12 (S329) ◽

pp. 151-155

Author(s):

L. M. Oskinova ◽

R. Ignace ◽

D. P. Huenemoerder

Keyword(s):

High Resolution ◽

Stellar Wind ◽

Massive Star ◽

Massive Stars ◽

Stellar Winds ◽

X Rays ◽

Early Type ◽

Stellar Rotation ◽

X Ray ◽

Early Type Stars

AbstractObservations with powerful X-ray telescopes, such as XMM-Newton and Chandra, significantly advance our understanding of massive stars. Nearly all early-type stars are X-ray sources. Studies of their X-ray emission provide important diagnostics of stellar winds. High-resolution X-ray spectra of O-type stars are well explained when stellar wind clumping is taking into account, providing further support to a modern picture of stellar winds as non-stationary, inhomogeneous outflows. X-ray variability is detected from such winds, on time scales likely associated with stellar rotation. High-resolution X-ray spectroscopy indicates that the winds of late O-type stars are predominantly in a hot phase. Consequently, X-rays provide the best observational window to study these winds. X-ray spectroscopy of evolved, Wolf-Rayet type, stars allows to probe their powerful metal enhanced winds, while the mechanisms responsible for the X-ray emission of these stars are not yet understood.

Download Full-text

Enhanced X-ray emission arising from laser-plasma confinement by a strong transverse magnetic field

Scientific Reports ◽

10.1038/s41598-021-87651-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Evgeny D. Filippov ◽

Sergey S. Makarov ◽

Konstantin F. Burdonov ◽

Weipeng Yao ◽

Guilhem Revet ◽

...

Keyword(s):

Magnetic Field ◽

Transverse Magnetic ◽

Radiative Properties ◽

Magnetic Field Direction ◽

Solid Target ◽

Total Plasma ◽

Plasma Confinement ◽

X Ray ◽

Magnetic Compression ◽

The Magnetic Field

AbstractWe analyze, using experiments and 3D MHD numerical simulations, the dynamic and radiative properties of a plasma ablated by a laser (1 ns, 10$$^{12}$$ 12 –10$$^{13}$$ 13 W/cm$$^2$$ 2 ) from a solid target as it expands into a homogeneous, strong magnetic field (up to 30 T) that is transverse to its main expansion axis. We find that as early as 2 ns after the start of the expansion, the plasma becomes constrained by the magnetic field. As the magnetic field strength is increased, more plasma is confined close to the target and is heated by magnetic compression. We also observe that after $$\sim 8$$ ∼ 8 ns, the plasma is being overall shaped in a slab, with the plasma being compressed perpendicularly to the magnetic field, and being extended along the magnetic field direction. This dense slab rapidly expands into vacuum; however, it contains only $$\sim 2\%$$ ∼ 2 % of the total plasma. As a result of the higher density and increased heating of the plasma confined against the laser-irradiated solid target, there is a net enhancement of the total X-ray emissivity induced by the magnetization.

Download Full-text

Magnetic Field Spectroheliograms from the San Fernando Observatory

Symposium - International Astronomical Union ◽

10.1017/s0074180900022774 ◽

1971 ◽

Vol 43 ◽

pp. 329-339 ◽

Cited By ~ 30

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.

Download Full-text

Chemical Abundances of Early Type Stars

Symposium - International Astronomical Union ◽

10.1017/s007418090011486x ◽

1998 ◽

Vol 188 ◽

pp. 224-225

Author(s):

S. Tanaka ◽

S. Kitamoto ◽

T. Suzuki ◽

K. Torii ◽

M.F. Corcoran ◽

...

Keyword(s):

Surface Layer ◽

Stellar Wind ◽

Nuclear Reactions ◽

X Rays ◽

Early Type ◽

Chemical Abundances ◽

X Ray ◽

Low Metallicity ◽

Early Type Stars

X-rays from early-type stars are emitted by the corona or the stellar wind. The materials in the surface layer of early-type stars are not contaminated by nuclear reactions in the stellar inside. Therefore, abundance study of the early-type stars provides us an information of the abundances of the original gas. However, the X-ray observations indicate low-metallicity, which is about 0.3 times of cosmic abundances. This fact raises the problem on the cosmic abundances.

Download Full-text

X‐Ray Emission from Early‐Type Stars in the Orion Nebula Cluster

The Astrophysical Journal Supplement Series ◽

10.1086/432375 ◽

2005 ◽

Vol 160 (2) ◽

pp. 557-581 ◽

Cited By ~ 112

Author(s):

B. Stelzer ◽

E. Flaccomio ◽

T. Montmerle ◽

G. Micela ◽

S. Sciortino ◽

...

Keyword(s):

Orion Nebula ◽

Early Type ◽

X Ray ◽

Early Type Stars

Download Full-text

Modelling of the Magnetic Configuration of CP Stars from Polarimetric Observations

Highlights of Astronomy ◽

10.1017/s153929960001844x ◽

1998 ◽

Vol 11 (2) ◽

pp. 679-681

Author(s):

M. Landolfi

Keyword(s):

Magnetic Field ◽

Stokes Parameter ◽

Quadratic Field ◽

Mean Field ◽

Longitudinal Component ◽

Stokes Parameters ◽

Longitudinal Field ◽

The Mean ◽

The Magnetic Field ◽

Polarized Radiation

The observational quantities commonly used to study the magnetic field of CP stars – the mean field modulus and the mean longitudinal field, as well as the ‘mean asymmetry of the longitudinal field’ and the ‘mean quadratic field’ recently introduced by Mathys (1995a,b) – are based either on the Stokes parameter / or on the Stokes parameter V. However, a complete description of polarized radiation requires the knowledge of the full Stokes vector: in other words, we should expect that useful information is also contained in linear polarization (the Stokes parameters Q and U); or rather we should expect the information contained in (Q, U) and in V to be complementary, since linear and circular polarization are basically related to the transverse and the longitudinal component of the magnetic field, respectively.

Download Full-text

How the Magnetic Field Impacts the Chiroptical Activities of Helical Copper Enantiomers

New Journal of Chemistry ◽

10.1039/d1nj03803f ◽

2021 ◽

Author(s):

jialu wu ◽

Bo Li ◽

Hong Wang ◽

Ying Zhen Lai ◽

Yue Ye ◽

...

Keyword(s):

Magnetic Field ◽

Solid State ◽

Thermogravimetric Analysis ◽

Single Crystal ◽

Structure Analysis ◽

Chiral Ligands ◽

X Ray ◽

The Magnetic Field

A pair of enantiomers {[Cu(L-pro)(L-tyr)]·2H2O}n (L-1) and {[Cu(D-pro)(D-tyr)]·2H2O}n (D-1) based on the chiral ligands L/D-proline and L/D-tyrosine were synthesized and investigated by single-crystal X-ray structure analysis, IR, thermogravimetric analysis, solid-state...

Download Full-text