scholarly journals Could the Magnetic Star HD 135348 Possess a Rigidly Rotating Magnetosphere?

2022 ◽  
Vol 924 (1) ◽  
pp. L10
Author(s):  
Rahul Jayaraman ◽  
Swetlana Hubrig ◽  
Daniel L. Holdsworth ◽  
Markus Schöller ◽  
Silva Järvinen ◽  
...  
Keyword(s):  
Magnetic Field ◽  
South African ◽  
Longitudinal Magnetic Field ◽  
Magnetic Star ◽  
Large Telescope ◽  
Emission Profile ◽  
Learning Classifier ◽  
Rotational Phase

Abstract We report the detection and characterization of a new magnetospheric star, HD 135348, based on photometric and spectropolarimetric observations. The TESS light curve of this star exhibited variations consistent with stars known to possess rigidly rotating magnetospheres (RRMs), so we obtained spectropolarimetric observations using the Robert Stobie Spectrograph (RSS) on the South African Large Telescope (SALT) at four different rotational phases. From these observations, we calculated the longitudinal magnetic field of the star 〈B z 〉, as well as the Alfvén and Kepler radii, and deduced that this star contains a centrifugal magnetosphere. However, an archival spectrum does not exhibit the characteristic “double-horned” emission profile for Hα and the Brackett series that has been observed in many other RRM stars. This could be due to the insufficient rotational phase coverage of the available set of observations, as the spectra of these stars significantly vary with the star’s rotation. Our analysis underscores the use of TESS in photometrically identifying magnetic star candidates for spectropolarimetric follow-up using ground-based instruments. We are evaluating the implementation of a machine-learning classifier to search for more examples of RRM stars in TESS data.

scholarly journals On the origin of Supergiant Fast X-ray Transients

2018 ◽  
Vol 14 (S346) ◽  
pp. 193-196
Author(s):  
Swetlana Hubrig ◽  
Lara Sidoli ◽  
Konstantin A. Postnov ◽  
Markus Schöller ◽  
Alexander F. Kholtygin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Stellar Wind ◽  
Longitudinal Magnetic Field ◽  
High Mass ◽  
Large Telescope ◽  
X Ray ◽  
Very Large Telescope ◽  
Low X ◽  
X Ray Binaries

Abstract. A fraction of high-mass X-ray binaries are supergiant fast X-ray transients. These systems have on average low X-ray luminosities, but display short flares during which their X-ray luminosity rises by a few orders of magnitude. The leading model for the physics governing this X-ray behaviour suggests that the winds of the donor OB supergiants are magnetized. In agreement with this model, the first spectropolarimetric observations of the SFXT IGR J11215-5952 using the FORS 2 instrument at the Very Large Telescope indicate the presence of a kG longitudinal magnetic field. Based on these results, it seems possible that the key difference between supergiant fast X-ray transients and other high-mass X-ray binaries are the properties of the supergiant’s stellar wind and the physics of the wind’s interaction with the neutron star magnetosphere.

scholarly journals First characterization of Swift J1845.7–0037 with NuSTAR

2020 ◽  
Vol 634 ◽  
pp. A89
Author(s):  
V. Doroshenko ◽  
S. Tsygankov ◽  
J. Long ◽  
A. Santangelo ◽  
S. Molkov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spectral Analysis ◽  
Neutron Star ◽  
X Ray ◽  
Transient Source ◽  
Broadband Spectrum ◽  
Cyclotron Line ◽  
The Magnetic Field

The hard X-ray transient source Swift J1845.7–0037 was discovered in 2012 by Swift/BAT. However, at that time, no dedicated observations of the source were performed. In October 2019, the source became active again, and X-ray pulsations with a period of ∼199 s were detected with Swift/XRT. This triggered follow-up observations with NuSTAR. Here, we report on the timing and spectral analysis of the source properties using NuSTAR and Swift/XRT. The main goal was to confirm pulsations and search for possible cyclotron lines in the broadband spectrum of the source to probe its magnetic field. Despite highly significant pulsations with period of 207.379(2) s being detected, no evidence for a cyclotron line was found in the spectrum of the source. We therefore discuss the strength of the magnetic field based on the source flux and the detection of the transition to the “cold-disc” accretion regime during the 2012 outburst. Our conclusion is that the source is most likely a highly magnetized neutron star with B ≳ 1013 G at a large distance of d ∼ 10 kpc. The latter is consistent with the nondetection of a cyclotron line in the NuSTAR energy band.

scholarly journals Magnetic Models Can Not Explain The Blazhko Effect in RR Lyrae Stars

2004 ◽  
Vol 193 ◽  
pp. 535-538
Author(s):  
M. Chadid ◽  
S.L.S. Shorlin ◽  
J.D. Landstreet
Keyword(s):  
Magnetic Field ◽  
Longitudinal Magnetic Field ◽  
Field Measurements ◽  
Magnetic Star ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Magnetic Field Measurements ◽  
Blazhko Effect ◽  
Bona Fide ◽  
Lyrae Stars

AbstractWe report a new series of high-precision Stokes V profiles and longitudinal magnetic field measurements of RR Lyrae, obtained with the MuSiCoS spectropolarimeter over a period of four years. These data provide no evidence whatsoever for a strong magnetic field in the photosphere of RRLyrae, which is consistent with Preston’s (1967) results, but inconsistent with apparent magnetic field detections by Babcock (1958) and Romanov et al. (1987, 1994). Following discussion of these disparate results, we conclude that RR Lyrae is a bona fide non-magnetic star, a conclusion which leads to the general falsification of models of the Blazkho effect requiring strong photospheric magnetic fields.

Refinement of metal structure in arc surfacing under the effect of longitudinal magnetic field

2019 ◽  
Vol 2019 (2) ◽  
pp. 19-21
Author(s):  
A.D. Razmyshlyaev ◽  
◽  
M.V. Ageeva ◽  
E.V. Lavrova ◽  
◽  
...  
Keyword(s):  
Magnetic Field ◽  
Longitudinal Magnetic Field ◽  
Metal Structure

What Matters to South African Bank Customers? A Case Study of four Main South African Banks

2015 ◽  
Vol 6 (1and2) ◽  
Author(s):  
Kingstone Mutsonziwa
Keyword(s):  
Customer Satisfaction ◽  
South African ◽  
Language Usage ◽  
Face To Face ◽  
Bank Resolution ◽  
African Context ◽  
Key Drivers ◽  
Investment Advice

This paper is a follow-up article based on the first article titled Customers speak for themselves: A case of Customer Satisfaction in the four Main South African Banks. Customer satisfaction within the banking industry is very important in the South African context. Although banks are trying their best to give their customers the best service, it is important to continuously measure customer satisfaction and identify service attributes that contribute to overall customer satisfaction for the banks. The data used in the analysis is based on a quantitative survey of 500 randomly selected customers in Pretoria, Johannesburg, Durban and Cape Town were interviewed using a face to face methodology. The key drivers of overall customer satisfaction based on regression analysis for the different banks were helpfulness and innovativeness (ABSA), helpfulness, innovativeness of the bank, resolution of problems and investment advice (FNB), language usage and friendliness of service consultants (Nedbank), innovativeness of the bank, investment advice and use of language (Standard bank). These attributes were important to the overall customer satisfaction and need to be closely monitored by the management of these banks.

Sign in / Sign up

Export Citation Format

Share Document