Characterizing the Rigidly Rotating Magnetosphere Stars Hd 345439 and Hd 23478

Wisniewski, John P.; Chojnowski, S. Drew; Davenport, James R. A.; Bartz, Jonathan; Pepper, Joshua; Whelan, David G.; Eikenberry, S. S.; Lomax, Jamie R.; Majewski, Steven R.; Richardson, Noel D.; Skrutskie, Michael F.

doi:10.1088/2041-8205/811/2/l26

Cited by 17 publications

(27 citation statements)

References 35 publications

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“…The stellar rotation period of ρ Oph A derived in Sec. 3 (≈ 0.75 days) is very close to the rotation period of another B2type star: HD 345439, P rot ≈ 0.77 days (Wisniewski et al 2015;Hubrig et al 2017). At the present time, ρ Oph A is the third-most rapidly rotating magnetic B-type star yet discovered, after HR 5907 (Grunhut et al 2012) andHR 7355 (Rivinius et al 2013), both stars having rotation periods of ≈ 0.5 days.…”

Section: The Orm Geometry Of ρ Oph Asupporting

confidence: 64%

Evidence for radio and X-ray auroral emissions from the magnetic B-type star ρ Oph A

Leto

Trigilio

Leone³

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present new ATCA multi-wavelength radio measurements (range 2.1-21.2 GHz) of the early-type magnetic star ρ Oph A, performed in March 2019 during 3 different observing sessions. These new ATCA observations evidence a clear rotational modulation of the stellar radio emission and the detection of coherent auroral radio emission from ρ Oph A at 2.1 GHz. We collected high-resolution optical spectra of ρ Oph A acquired by several instruments over a time span of about ten years. We also report new magnetic field measurements of ρ Oph A that, together with the radio light curves and the temporal variation of the equivalent width of the He I line (λ = 5015Å), were used to constrain the rotation period and the stellar magnetic field geometry. The above results have been used to model the stellar radio emission, modelling that allowed us to constrain the physical condition of ρ Oph A's magnetosphere. Past XMM-Newton measurements showed periodic X-ray pulses from ρ Oph A. We correlate the X-ray light curve with the magnetic field geometry of ρ Oph A. The already published XMM-Newton data have been re-analyzed showing that the X-ray spectra of ρ Oph A are compatible with the presence of a non-thermal X-ray component. We discuss a scenario where the emission phenomena occurring at the extremes of the electromagnetic spectrum, radio and X-ray, are directly induced by the same plasma process. We interpret the observed X-ray and radio features of ρ Oph A as having an auroral origin.

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Section: The Orm Geometry Of ρ Oph Asupporting

confidence: 64%

Evidence for radio and X-ray auroral emissions from the magnetic B-type star ρ Oph A

Leto

Trigilio

Leone³

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…With time baselines of up to 10 yr, a typical cadence of 30 minutes, and the precision to detect periodic signals down to approximately one to a few millimagnitudes, KELT light curves are well-suited to the detection of the periodic variability exhibited by β Cephei stars. The utility of KELT light curves to detect periodic oscillations in brightness was demonstrated by Cargile et al (2014), Wisniewski et al (2015), and Labadie-Bartz et al (2017).…”

Section: Datamentioning

confidence: 99%

New Beta Cephei Stars from the KELT Project

Labadie-Bartz

Handler

Pepper

et al. 2020

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We present the results of a search for Galactic β Cephei stars, which are massive pulsating stars with both pressure modes and mixed modes. Thus, these stars can serve as benchmarks for seismological studies of the interiors of massive stars. We conducted the search by performing a frequency analysis on the optical light curves of known Oand B-type stars with data from the Kilodegree Extremely Little Telescope exoplanet survey. We identify 113 β Cephei stars, of which 86 are new discoveries, which altogether represent a 70% increase in the number currently known. An additional 97 candidates are identified. Among our targets, we find five new eclipsing binaries and 22 stars with equal frequency spacings suggestive of rotational splitting of nonradial pulsation modes. Candidates for runaway stars among our targets and a number of interesting individual objects are discussed. Most of the known and newly discovered β Cephei stars will be observed by the Transiting Exoplanet Survey Satellite mission, providing by far the most comprehensive observational data set of massive main-sequence pulsating stars of sufficient quality for detailed asteroseismic studies. Future analysis of these light curves has the potential to dramatically increase our understanding of the structure of stellar interiors and the physical processes taking place therein. Unified Astronomy Thesaurus concepts: Beta Cepheid variable stars (148); Asteroseismology (73); Stellar oscillations (1617); Multi-periodic variable stars (1079); Pulsating variable stars (1307); Short period variable stars (1453); Early-type variable stars (432); Light curves (918); Light curve classification (1954); Surveys (1671); B stars (128) Supporting material: data behind figure, machine-readable tables

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“…Landstreet & Borra 1978). Using Kilodegree Extremely Little Telescope (KELT) photometry, Wisniewski et al (2015) detected a rotation period of 0.7701 ± 0.0003 d with the zero point of the ephemeris JD = 2454252.3432 corresponding to the first minimum in the light curve (see their Fig. 1.).…”

Section: Period Determination From the Magnetic Datamentioning

confidence: 99%

“…Such stars are extremely rare: the discovery of HD 23478 and HD 345439 has enhanced the number of "extreme" rotators by 50% (Eikenberry et al 2014). The authors reported that the optical spectra of HD 345439 reveal strong He i lines and very fast rotation of ∼ 270 ± 20 km s −1 Subsequently, Wisniewski et al (2015) analysed multi-epoch photometric observations of this star from the Kilodegree Extremely Little Telescope, Wide Angle Search for Planets, and ASAS surveys revealing the presence of a ∼0.7701 day rotation period in each data set. The authors suggest that the He-strong star HD 345439 of spectral type B2 V is among the faster known He-strong σ Ori E analogs, ⋆ E-mail: shubrig@aip.de HR 7355 (P rot = 0.52 d - Rivinius et al 2013) and HR 5907 (P rot = 0.51 d - Grunhut et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Characterizing the magnetic field and spectral variability of the rigidly rotating magnetosphere star HD 345439

Hubrig

Холтыгин

Schöller

et al. 2017

Monthly Notices of the Royal Astronomical Society: Letters

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A team involved in APOGEE, one of the Sloan Digital Sky Survey III programs, recently announced the discovery of two rare rigidly rotating magnetosphere stars, HD 345439 and HD 23478. Near-infrared spectra of these objects revealed emission-line behavior identical to that previously discovered in the helium-strong star σ Ori E, which has a strong magnetic field and rotates fast. A single spectropolarimetric observation of HD 345439 with FORS 2 at the VLT in 2014 over 88 min indicated that HD 345439 may host a strong, rapidly varying magnetic field. In this work, we present the results of our spectropolarimetric monitoring of this star with FORS 2, which revealed the presence of a strong longitudinal magnetic field dominated by a dipolar component. The analysis of spectral variability indicates an opposite behaviour of He and Si lines, which is usually attributed to differences in the distribution of surface He and Si abundance spots.

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Characterizing the Rigidly Rotating Magnetosphere Stars Hd 345439 and Hd 23478

Cited by 17 publications

References 35 publications

Evidence for radio and X-ray auroral emissions from the magnetic B-type star ρ Oph A

Evidence for radio and X-ray auroral emissions from the magnetic B-type star ρ Oph A

New Beta Cephei Stars from the KELT Project

Characterizing the magnetic field and spectral variability of the rigidly rotating magnetosphere star HD 345439

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