The Nova Shell and Evolution of the Recurrent Nova T Pyxidis

Schaefer, Bradley E.; Pagnotta, Ashley; Shara, Michael M.

doi:10.1088/0004-637x/708/1/381

Cited by 68 publications

(168 citation statements)

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“…The evolution of the nova is relatively slow, thereby providing time and scope for organizing joint observations with optical interferometry arrays such as CHARA and the VLTI. T Pyx is surrounded by an interesting nebula in expansion that has been investigated by the HST for more than ten years (Schaefer et al 2010, and references therein). The knots are expanding in the plane of the sky with velocities ranging from roughly 500 to 715 km s −1 .…”

Section: Introductionmentioning

confidence: 99%

The 2011 outburst of the recurrent nova T Pyxidis. Evidence for a face-on bipolar ejection

Chesneau¹,

Meilland²,

Banerjee³

et al. 2011

A&A

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Aims. T Pyx is the first recurrent nova ever historically studied. It was seen in outburst six times between 1890 and 1966 and then not for 45 years. We report on near-IR interferometric observations of the recent outburst of 2011. Methods. We obtained near-IR observations of T Pyx at dates ranging from t = 2.37 d to t = 48.2 d after the outburst, with the CLASSIC recombiner located at the CHARA array and with the PIONIER and AMBER recombiners located at the VLTI array. These data are supplemented with near-IR photometry and spectra obtained at Mount Abu, India. We compare expansion of the H and K band continua and the Brγ emission line, and infer information on the kinematics and morphology of the early ejecta. Results. Slow expansion velocities were measured (≤300 km s −1 ) before t = 20 d. From t = 28 d on, the AMBER and PIONIER continuum visibilities (K and H band, respectively) are best simulated with a two-component model consisting of an unresolved source plus an extended source whose expansion velocity onto the sky plane is lower than ∼700 km s −1 . The expansion of the Brγ lineforming region, as inferred at t = 28 d and t = 35 d, is slightly larger, implying velocities in the range 500−800 km s −1 , which is still strikingly lower than the velocities of 1300−1600 km s −1 inferred from the Doppler width of the line. Moreover, a remarkable pattern was observed in the Brγ differential phases. A semi-quantitative model using a bipolar flow with a contrast of 2 between the pole and equator velocities, an inclination of i = 15• , and a position angle PA = 110• provides a good match to the AMBER observables. At t = 48 d, a PIONIER dataset confirms the two-component nature of the H band emission, consisting of an unresolved stellar source and an extended region whose appearance is circular and symmetric within error bars. Conclusions. These observations are most simply interpreted within the frame of a bipolar model, oriented nearly face-on. This finding has profound implications for interpreting past, current, and future observations of the expanding nebula.

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Section: Introductionmentioning

confidence: 99%

The 2011 outburst of the recurrent nova T Pyxidis. Evidence for a face-on bipolar ejection

Chesneau¹,

Meilland²,

Banerjee³

et al. 2011

A&A

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“…I determined an approximate nebular and point source count rate by using the PSF-subtracted total image (merged) of the nebula within about a radius of 5 (the circular extraction area is shown in Fig. 3a; the large circle), since it is about the size of the optical remnant (see Schaefer et al 2010) and the Chandra nebulosity is within 2 of the point source. As in the imaging analysis discussed/outlined above, I used either no smoothing or 1 × 1 pixel and 2 × 2 pixel smoothing for both the PSF and the merged source image with the 0.1 ACIS pixel scale to obtain an approximate nebular count rate.…”

Section: On the Extended Emission Around T Pyxmentioning

confidence: 99%

Pre-outburstChandraobservations of the recurrent nova T Pyxidis

Balman

2014

A&A

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Aims. I study the spectral, temporal, and spatial characteristics of the quiescent X-ray emission (not in outburst) of the recurrent nova T Pyx. Methods. I performed the spectral analysis of the X-ray data obtained using the Chandra Observatory, Advanced CCD Imaging Spectrometer (ACIS-S3) detector. I fit the spectra with several models that describe plasma emission characteristics. In addition, I calculated the light curve of the data and performed power spectral analysis using Fourier transform. Finally, I did high-resolution imaging analysis of the data at the subpixel level and produced radial surface brightness profiles.Results. I present a total of 98.8 ks (∼3 × 30 ks) observation of T Pyx obtained with the ACIS-S3 detector onboard the Chandra Observatory obtained during the quiescent phase, about 2−3 months before its outburst in April 2011. The total Chandra spectrum of the source T Pyx gives a maximum temperature kT max > 37.0 keV (2σ lower limit) with (0.9−1.5) × 10 −13 erg s −1 cm −2 and (1.3−2.2) × 10 32 erg s −1 (at 3.5 kpc) in the 0.1−50 keV range using a multitemperature plasma emission model with a power-law distribution of temperatures (i.e., CEVMKL in XSPEC). I find a ratio of (L x /L disk ) (2−7) × 10 −4 and the ratio is smaller if L disk is higher than 3 × 10 35 erg s −1 indicating considerable inefficiency of emission in the boundary layer. There is no soft X-ray blackbody emission from T Pyx with a 2σ upper limit on the blackbody temperature and the flux/luminosity as kT BB < 25 eV and L soft < 2.0 × 10 33 erg s −1 in the 0.1−10.0 keV band. All fits yield only interstellar N H during quiescence. I suggest that T Pyx has an optically thin boundary layer merged with an advection-dominated accretion flow and/or X-ray corona in the inner disk indicating ongoing quasi-spherical accretion at (very) high rates during quiescent phases. Such a boundary layer structure may be excessively heating the white dwarf, influencing the thermonuclear runaway leading to the recurrent nova events. The orbital period of the system is detected in the power spectrum of the Chandra light curves with no energy dependence over the orbit. The central source (i.e., the binary system) emission and its spectrum is deconvolved from any possible extended emission with a long and detailed procedure at the subpixel level revealing an extended emission with S /N ∼ 6−10. The derived shape looks like an elliptical nebula with a semi-major axis ∼1.0 arcsec and a semi-minor axis ∼0.5 arcsec, also indicating an elongation towards south. The calculated approximate count rate of the extended emission is 0.0013−0.0025 c s −1 . The luminosity (within errors) of the nebula is ∼(0.6−30.0) × 10 31 erg s −1 (at 3.5 kpc) mostly correct towards the lower end of the range. The nebulosity seems consistent with an interaction of the outflow/ejecta from the 1966 outburst.

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“…This period change will then give the ejected mass with high accuracy and no need for uncertain quantities (like the distance) or dubious assumptions (like the shell filling factors). For the case of T Pyx (but not for the other RNe), the dynamical friction of the companion star within the nova envelope will also cause a small period change (Livio 1991;Schaefer et al 2010a), and this effect must also be taken into account. The ejected mass is critical for knowing whether the RN white dwarf is gaining or losing mass over the eruption cycle, and hence whether the RN will soon become a Type Ia supernova.…”

Section: Orbital Period Just Before the Eruption P Prementioning

confidence: 99%

“…T Pyx is the only RN that has a nova shell, and this shell has a surprisingly slow expansion velocity plus a structure of thousands of discrete knots (Duerbeck & Seitter 1979;Williams 1982;Shara et al 1989Shara et al , 1997. The homologous expansion of the individual shell fragments proves that they suffer no significant deceleration, and the expansion velocities, viewed over 13 yr by Hubble Space Telescope, prove that the nova shell was ejected in the year 1866 ± 5 at a velocity of 500-715 km s −1 (Schaefer et al 2010a). This velocity is greatly too low to be from an RN event, and with the measured mass in the shell (∼10 −4.5 M ) being much greater than is possible for an RN event, we know that the 1866 event must have been a normal classical nova eruption with a very long time of prior quiescence (Schaefer et al 2010a).…”

Section: Introductionmentioning

confidence: 97%

“…This dilemma was solved by Knigge et al (2000), who realized that the high accretion rate could be powered by a hot-luminous source on the white dwarf that is irradiating the companion star. For T Pyx, this idea was extended by Schaefer et al (2010a), where the classic nova eruption of 1866 started a high accretion rate which drives a largely self-sustained supersoft source (with nuclear burning on the surface of the white dwarf). This mechanism can only work for binaries with short orbital periods and where a substantial magnetic field channels the material into a small area.…”

Section: Introductionmentioning

confidence: 99%

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The 2011 Eruption of the Recurrent Nova T Pyxidis: The Discovery, the Pre-Eruption Rise, the Pre-Eruption Orbital Period, and the Reason for the Long Delay

Schaefer

Landolt

Linnolt

et al. 2013

ApJ

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We report the discovery by M. Linnolt on JD 2, 455,665.7931 (UT 2011 April 14.29) of the sixth eruption of the recurrent nova T Pyxidis. This discovery was made just as the initial fast rise was starting, so with fast notification and response by observers worldwide, the entire initial rise was covered (the first for any nova), and with high time resolution in three filters. The speed of the rise peaked at 9 mag day −1 , while the light curve is well fit over only the first two days by a model with a uniformly expanding sphere. We also report the discovery by R. Stubbings of a pre-eruption rise starting 18 days before the eruption, peaking 1.1 mag brighter than its long-time average, and then fading back toward quiescence 4 days before the eruption. This unique and mysterious behavior is only the fourth known (with V1500 Cyg, V533 Her, and T CrB) anticipatory rise closely spaced before a nova eruption. We present 19 timings of photometric minima from 1986 to 2011 February, where the orbital period is fast increasing with P /Ṗ = +313,000 yr. From 2008 to 2011, T Pyx had a small change in this rate of increase, so that the orbital period at the time of eruption was 0.07622950 ± 0.00000008 days. This strong and steady increase of the orbital period can only come from mass transfer, for which we calculate a rate of (1.7-3.5) × 10 −7 M yr −1 . We report 6116 magnitudes between 1890 and 2011, for an average B = 15.59 ± 0.01 from 1967 to 2011, which allows for an eruption in 2011 if the blue flux is nearly proportional to the accretion rate. The ultraviolet-optical-infrared spectral energy distribution is well fit by a power law with f ν ∝ ν 1.0 , although the narrow ultraviolet region has a tilt with a fit of f ν ∝ ν 1/3 . We prove that most of the T Pyx light is not coming from a disk, or any superposition of blackbodies, but rather is coming from some nonthermal source. We confirm the extinction measure from IUE with E(B − V ) = 0.25 ± 0.02 mag.

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The Nova Shell and Evolution of the Recurrent Nova T Pyxidis

Cited by 68 publications

References 58 publications

The 2011 outburst of the recurrent nova T Pyxidis. Evidence for a face-on bipolar ejection

The 2011 outburst of the recurrent nova T Pyxidis. Evidence for a face-on bipolar ejection

Pre-outburstChandraobservations of the recurrent nova T Pyxidis

The 2011 Eruption of the Recurrent Nova T Pyxidis: The Discovery, the Pre-Eruption Rise, the Pre-Eruption Orbital Period, and the Reason for the Long Delay

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