X-ray and optical observations of BY Cam

We present preliminary results of an analysis of X-ray and optical data of the asynchronous AM Her star BY Cam [1]. We use X-ray data from EXOSAT (0.1… 50 keV), Ginga (1.5… 50 keV) and ROSAT (0.1…2.0 keV) and optical data obtained during a 45-day campaign in 1994.There are 4 known periods: the orbital period (201.30 m), the spin period of the white dwarf (199.3303 m), a spin-orbit beat period (14.15 d) and a side-band period (197.4 m). The detection of this side-band period lends credence to the theory of [2], who suggest that for a stream accreting, diskless, magnetic CV a frequency, f = 2ωspin − Ωorb (=197.399 m), will appear as a strong spike in the power spectrum for certain systems. Wu & Mason (this volume) discuss a competing model where Pspin = 197.4 m.

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RX J1015.5+0904: A New Polar at the Lower Period Limit

International Astronomical Union Colloquium ◽

10.1017/s0252921100038744 ◽

1996 ◽

Vol 158 ◽

pp. 229-230

Author(s):

V. Burwitz ◽

K. Reinsch ◽

A. D. Schwope ◽

K. Beuermann ◽

S. Mengel ◽

...

Keyword(s):

Orbital Period ◽

Optical Observations ◽

Optical Data ◽

X Ray ◽

First Results ◽

Period Limit ◽

Lower Period

AbstractWe present X-ray and optical observations of the ROSAT discovered polar (AM Her binary) RX J1015.5+0904 and first results of our analysis of the X-ray and optical data. These results indicate a one-pole accretion geometry and an orbital period of P = 79.88 m for this V ~ 17 mag system.

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TESS observations of the asynchronous polar CD Ind: mapping the changing accretion geometry

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz992 ◽

2019 ◽

Vol 486 (2) ◽

pp. 2549-2556 ◽

Cited By ~ 2

Author(s):

Pasi Hakala ◽

Gavin Ramsay ◽

Stephen B Potter ◽

Andrew Beardmore ◽

David A H Buckley ◽

...

Keyword(s):

Light Curve ◽

White Dwarf ◽

Pulse Shape ◽

Optical Observations ◽

Mapping Technique ◽

Beat Period ◽

Spin Period ◽

Cyclotron Emission

ABSTRACT We present the results of near continuous TESS optical observations of the asynchronous polar CD Ind (RX J2115−5840). The 27.9 d long light curve, with 2 min resolution, reveals remarkable changes in the magnetic accretion geometry of the system over the 7.3 d beat period. We have modelled the changes in the optical spin period pulse shape using a cyclotron emission mapping technique. The resulting cyclotron emission maps of the magnetic white dwarf reveal how the accretion geometry changes from single- to two-pole accretion and back over the beat cycle. Finally, we present the results from particle-based numerical magnetic accretion simulations, which agree with our interpretation of the changing accretion scenario.

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RX J0524+42: A New Asynchronous Magnetic CV

International Astronomical Union Colloquium ◽

10.1017/s025292110000213x ◽

2004 ◽

Vol 190 ◽

pp. 230-236

Author(s):

Robert Schwarz ◽

A. D. Schwope ◽

A. Staude ◽

T. Urrutia ◽

A. Rau ◽

...

Keyword(s):

White Dwarf ◽

Orbital Motion ◽

Optical Photometry ◽

Side Band ◽

Beat Period ◽

Spin Period ◽

Minute Period

AbstractExtensive optical photometry of the canditate magnetic CV RX J0524+42 has uncovered three persistent periods at 157, 146 and 136 minutes, which are the manifestation of the orbital motion of the system, the white dwarf spin and a possible side-band period of the latter. Depending on the interpretation of the 146 or the 136 minute period as the spin period, the system is an asynchronous by 7% or 14% (1 – PSpin/Porb), and therefore intermediate between the near-synchronous polars (< 2%) and the two DQ Her stars with long spin periods (EX Hya and V1025 Cen). Sampling the data over the beat period of 1.4 or 0.7 days reveals a prominent double-humped modulation on the spin period for certain fractions of the beat cycle. The phasing of this modulation strongly suggests that either pole switching onto two diametrically opposed accretion sites, or pole migration is operating in this system. With a period right within the period gap, RX J0524+42 is a key object for MCV evolution: it might be the first transition object between the DQ and AM Her subclasses where the white dwarf is currently in the process of synchronisation.

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The Relation between Spin and Orbital Periods in HMXBs

Symposium - International Astronomical Union ◽

10.1017/s0074180900194422 ◽

2003 ◽

Vol 214 ◽

pp. 215-217

Author(s):

Q. Z. Liu ◽

X. D. Li ◽

D. M. Wei

Keyword(s):

Magnetic Fields ◽

Orbital Period ◽

Critical Line ◽

High Mass ◽

Orbital Eccentricity ◽

X Ray ◽

Spin Period ◽

Orbital Periods ◽

X Ray Binaries

The relation between the spin period (Ps) and the orbital period (Po) in high-mass X-ray binaries (HMXBs) is investigated. In order for Be/X-ray binaries to locate above the critical line of observable X-ray emission due to accretion, it is necessary for an intermediate orbital eccentricity to be introduced. We suggest that some peculiar systems in the Po − Ps diagram are caused by their peculiar magnetic fields.

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An X-ray and optical study of the outbursting behaviour of the SMC Be X-ray binary SXP 91.1

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2262 ◽

2019 ◽

Vol 489 (1) ◽

pp. 993-999 ◽

Cited By ~ 1

Author(s):

I M Monageng ◽

M J Coe ◽

J A Kennea ◽

L J Townsend ◽

D A H Buckley ◽

...

Keyword(s):

Neutron Star ◽

Gravitational Lensing ◽

Optical Data ◽

Type I ◽

X Ray ◽

Spin Period ◽

Average Spin ◽

Period Derivative ◽

Inclination Angles ◽

Using Data

ABSTRACT In this paper we report on the optical and X-ray behaviour of the Be X-ray binary, SXP 91.1, during a recent type I outburst. We monitored the outburst using the Neil Gehrels Swift Observatory. These data were supported by optical data from the Southern African Large Telescope and the Optical Gravitational Lensing Experiment (OGLE) to show the circumstellar disc activity. Matter from this disc accretes on to the neutron star, giving rise to the X-ray outburst as seen in the synchronous evolution of the optical and X-ray light curves. Using data taken with OGLE we show that the circumstellar disc has exhibited stable behaviour over two decades. A positive correlation is seen between the colour and magnitude from the OGLE and massive compact halo object observations, which indicates that the disc is orientated at relatively low-inclination angles. From the OGLE and Swift data, we demonstrate that the system has shown relative phase offsets that have persisted for many years. The spin period derivative is seen to be at maximum spin-up at phases when the mass accretion rate is at maximum. We show that the neutron star in SXP 91.1 is an unusual member of its class in the sense that it has had a consistent spin period derivative over many years, with the average spin-up rate being one of the highest for known Small Magellanic Cloud pulsars. The most recent measurements of the spin-up rate reveal higher values than the global trend, which is attributed to the recent mass accretion event leading to the current outburst.

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New observations of DW Cnc: where is the 38 min signal?

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa856 ◽

2020 ◽

Vol 494 (3) ◽

pp. 4110-4118

Author(s):

O Segura Montero ◽

S H Ramírez ◽

J Echevarría

Keyword(s):

Mass Transfer ◽

Power Spectrum ◽

Radial Velocity ◽

Orbital Period ◽

Velocity Analysis ◽

Doppler Tomography ◽

Sudden Drop ◽

Velocity Modulation ◽

Beat Period ◽

Low Mass

ABSTRACT We present extensive radial velocity observations of the intermediate polar DW Cnc during its 2018–2019 low state. We show that the 86 min signal associated with the orbital period is strong in our radial velocity analysis, power spectrum search, and in our Doppler tomography. However, we find that the velocity modulation associated with the 70 min beat period and the 38 min spin cycle is dramatically weaker than that previously observed. We put forward two interpretations for this change. The first is that a sudden drop into a low state detected in 2018–2019 caused an episode of low mass transfer from the companion, thus inhibiting the lighthouse effect produced by the rebound emission. The second is that this is a consequence of a rare outburst detected in 2007 by Crawford et al. (2008). We find this post-outburst hypothesis to be less likely. If the first scenario is correct, we predict that DW Cnc will recover its intermediate polar characteristics. A new ephemeris is presented by combining Patterson et al. (2004) radial velocities with ours.

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Optical Photometry of LMXBs: UW CrB (=MS 1603+260) and V1408 Aql (=4U 1957+115)

Acta Polytechnica CTU Proceedings ◽

10.14311/app.2015.02.0050 ◽

2015 ◽

Vol 2 (1) ◽

pp. 50-54

Author(s):

P. A. Mason ◽

E. L. Robinson ◽

S. Gomez ◽

J. V. Segura

Keyword(s):

Black Hole ◽

Orbital Period ◽

Light Curves ◽

Optical Data ◽

Published Data ◽

Type I ◽

Optical Photometry ◽

Mean Intensity ◽

X Ray ◽

Low Mass

We present new optical observations of V1408 Aql (= 4U 1957+115), the only low mass X-ray binary, black hole candidate known to be in a persistently soft state. We combine new broadband optical photometry with previously published data and derive a precise orbital ephemeris. The optical light curves display sinusoidal variations modulated on the orbital period as well as large night to night changes in mean intensity. The amplitude of the variations increases with mean intensity while maintaining sinusoidal shape. Considering the set of constraints placed by the X-ray and optical data we argue that V1408 Aql may harbor a very low mass black hole. Optical light curves of UW CrB display partial eclipses of the accretion disk by the donor star that vary both in depth and orbital phase. The new eclipses of UW CrB in conjunction with published eclipse timings are well fitted with a linear ephemeris. We derive an upper limit to the rate of change of the orbital period. By including the newly observed type I bursts with published bursts in our analysis, we find that optical bursts are not observed between orbital phases 0.93 and 0.07, i.e. they are not observable during partial eclipses of the disk.

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The Spin-Up Rate of the White Dwarf in GK Per

International Astronomical Union Colloquium ◽

10.1017/s0252921100001937 ◽

2004 ◽

Vol 190 ◽

pp. 120-123

Author(s):

Christopher W. Mauche

Keyword(s):

White Dwarf ◽

Light Curves ◽

Optical Measurements ◽

Pulse Period ◽

X Ray ◽

Spin Period

AbstractWe use hard X-ray light curves measured by the Chandra HETG and RXTE PCA during the late rise and plateau phases of the 2002 March–April outburst of the intermediate polar GK Per to determine that its X-ray pulse period P = 351.332 ± 0.002 s. Combined with previous X-ray and optical measurements of the spin period of the white dwarf, we find that its spin-up rate Ṗ = 0.00027 ± 0.00005 s yr−1.

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Spectroscopic and Photometric Observations of the Magnetic Cataclysmic Variable TX Col

International Astronomical Union Colloquium ◽

10.1017/s0252921100001998 ◽

2004 ◽

Vol 190 ◽

pp. 156-162

Author(s):

Nceba Mhlahlo ◽

Stephen B. Potter ◽

David Buckley

Keyword(s):

Orbital Period ◽

Power Spectra ◽

Radial Velocities ◽

Cataclysmic Variable ◽

Beat Period ◽

Spin Period ◽

Photometric Observations ◽

Optical Wavelengths ◽

First Time

AbstractSimultaneous photometry and spectroscopy of the Intermediate Polar TX Col were obtained in order to investigate its accretion mode and dynamics. The spectroscopic and photometric power spectra of TX Col are observed to change on relatively short timescales. Spectroscopy reveals a dominant periodicity at the orbital period (5.69 hr) and a spin period of 1909 s in radial velocities, while line equivalent widths show a strong periodicity at the beat period (2106 s). It is the first time that the orbital period has been detected in optical wavelengths.

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