Dissecting the donor star in the eclipsing polar HU Aquarii

Schwope, A. D.; Horne, K.; Steeghs, D.; Still, M.

doi:10.1051/0004-6361/201016373

Cited by 19 publications

(21 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Numbers in parentheses represent the uncertainty at the last significant digit. Total mass of the binary is 0.98 M (Schwope et al 2011 10. Colour-coded parameter scans of (χ 2 ν ) 1/2 around the best-fit one-planet model, to quadratic ephemeris and the optical measurements (Fit II in Table 4).…”

Section: Single-planet Models To All Recent Datamentioning

confidence: 99%

See 1 more Smart Citation

On the HU Aquarii planetary system hypothesis

Goździewski

Nasıroğlu

Słowikowska

et al. 2012

Monthly Notices of the Royal Astronomical Society

130

View full text Add to dashboard Cite

In this work, we investigate the eclipse timing of the polar binary HU Aquarii that has been observed for almost two decades. Recently, Qian et al. attributed large (O-C) deviations between the eclipse ephemeris and observations to a compact system of two massive jovian companions. We improve the Keplerian, kinematic model of the Light Travel Time (LTT) effect and re-analyse the whole currently available data set. We add almost 60 new, yet unpublished, mostly precision light curves obtained using the time high-resolution photo-polarimeter OPTIMA, as well as photometric observations performed at the MONET/N, PIRATE and TCS telescopes. We determine new mid--egress times with a mean uncertainty at the level of 1 second or better. We claim that because the observations that currently exist in the literature are non-homogeneous with respect to spectral windows (ultraviolet, X-ray, visual, polarimetric mode) and the reported mid--egress measurements errors, they may introduce systematics that affect orbital fits. Indeed, we find that the published data, when taken literally, cannot be explained by any unique solution. Many qualitatively different and best-fit 2-planet configurations, including self-consistent, Newtonian N-body solutions may be able to explain the data. However, using high resolution, precision OPTIMA light curves, we find that the (O-C) deviations are best explained by the presence of a single circumbinary companion orbiting at a distance of ~4.5 AU with a small eccentricity and having ~7 Jupiter-masses. This object could be the next circumbinary planet detected from the ground, similar to the announced companions around close binaries HW Vir, NN Ser, UZ For, DP Leo or SZ Her, and planets of this type around Kepler-16, Kepler-34 and Kepler-35.Comment: 20 pages, 18 figures, accepted to Monthly Notices of the Royal Astronomical Society (MNRAS

show abstract

Section: Single-planet Models To All Recent Datamentioning

confidence: 99%

“…According to the most recent work of Schwope et al (2011) the inclination of the binary is ∼87 • ± 0. • 8.…”

mentioning

confidence: 99%

On the HU Aquarii planetary system hypothesis

Goździewski

Nasıroğlu

Słowikowska

et al. 2012

Monthly Notices of the Royal Astronomical Society

130

View full text Add to dashboard Cite

show abstract

“…Our data shows no signs of a varying width or height of the ingress or egress feature, over time nor with changing accretion rate. Assuming for the masses M wd = 0.80 M⊙ and M2 = 0.18 M⊙, an inclination i = 87 • (Schwope et al 2011) and the orbital period from equation 2, we arrive at an orbital velocity of the M-dwarf of 479 km/s and a maximum spot diameter of Dspot ≃ 3829 km. Using the mass-radius relation of Verbunt & Rappaport (1988) for the white dwarf, this corresponds to a fractional area on the white dwarf of 0.018 and an opening angle of the accretion spot of ∼ 30 • .…”

Section: Ever-changing Light Curvesmentioning

confidence: 99%

Testing the planetary models of HU Aquarii

Bours

Marsh

Breedt

et al. 2014

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present new eclipse observations of the polar (i.e. semi-detached magnetic white dwarf + M-dwarf binary) HU Aqr, and mid-egress times for each eclipse, which continue to be observed increasingly early. Recent eclipses occurred more than 70 seconds earlier than the prediction from the latest model that invoked a single circumbinary planet to explain the observed orbital period variations, thereby conclusively proving this model to be incorrect. Using ULTRACAM data, we show that mid-egress times determined for simultaneous data taken at different wavelengths agree with each other. The large variations in the observed eclipse times cannot be explained by planetary models containing up to three planets, because of poor fits to the data as well as orbital instability on short time scales. The peak-to-peak amplitude of the O-C diagram of almost 140 seconds is also too great to be caused by Applegate's mechanism, movement of the accretion spot on the surface of the white dwarf, or by asynchronous rotation of the white dwarf. What does cause the observed eclipse time variations remains a mystery.

show abstract

“…Opportunities to reconstruct the evolution of the close binary through the presence of a planetary system were studied by Portegies Zwart (2013). The stellar and binary parameters were updated by Schwope et al (2011) who derive a total mass of the close binary of 0.98 ± 0.10 M .…”

Section: Introductionmentioning

confidence: 99%

On the ephemeris of the eclipsing polar HU Aquarii

Schwope

Thinius

2014

Astron Nachr

View full text Add to dashboard Cite

The magnetic cataclysmic variable HU Aquarii displayed pronounced quasi-periodic modulations of its eclipse timing. These were interpreted in terms of the light-travel time (LTT) effect caused by a circumbinary planet or planetary system. We report new photometric observations that revealed another precise eclipse timing for the October 2013 epoch, the first obtained in a high accretion state after many years in low or intermediate states. The eclipse was observed to occur earlier by 95.3 ± 2.0 s or 62.8 ± 2.0 s than expected for an assumed linear or quadratic ephemeris, respectively. The implied apparent strong evolution of the orbital period calls for a revision of the current planetary model or the planetary parameters. The object deserves further monitoring to uncover the true nature of the observed variability and to constrain the properties of the proposed planet or planetary system. The new observations prove that advanced amateur equipment can successfully be used in the growing field of planet search in wide circumbinary orbits via the LTT effect.

show abstract

Dissecting the donor star in the eclipsing polar HU Aquarii

Cited by 19 publications

References 25 publications

On the HU Aquarii planetary system hypothesis

On the HU Aquarii planetary system hypothesis

Testing the planetary models of HU Aquarii

On the ephemeris of the eclipsing polar HU Aquarii

Contact Info

Product

Resources

About