The detection1 of a dust disk around the white dwarf star G29-38 and transits from debris orbiting the white dwarf WD 1145+017 (ref. 2) confirmed that the photospheric trace metals found in many white dwarfs3 arise from the accretion of tidally disrupted planetesimals4. The composition of these planetesimals is similar to that of rocky bodies in the inner Solar System5. Gravitational scattering of planetesimals towards the white dwarf requires the presence of more massive bodies6, yet no planet has so far been detected at a white dwarf. Here we report optical spectroscopy of a hot (about 27,750 kelvin) white dwarf, WD J091405.30+191412.25, that is accreting from a circumstellar gaseous disk composed of hydrogen, oxygen and sulfur at a rate of about 3.3 × 109 grams per second. The composition of this disk is unlike all other known planetary debris around white dwarfs7, but resembles predictions for the makeup of deeper atmospheric layers of icy giant planets, with H2O and H2S being major constituents. A giant planet orbiting a hot white dwarf with a semi-major axis of around 15 solar radii will undergo substantial evaporation with expected mass loss rates comparable to the accretion rate that we observe onto the white dwarf. The orbit of the planet is most probably the result of gravitational interactions, indicating the presence of additional planets in the system. We infer an occurrence rate of approximately 1 in 10,000 for spectroscopically detectable giant planets in close orbits around white dwarfs.
Cloudy is publicly available (https://www.nublado.org/). The model atmosphere code of D. Koester is subject to restricted availability.
Zuckerman, B. & Becklin, E. E. Excess infrared radiation from a white dwarf—an orbiting brown dwarf? Nature 330, 138–140 (1987).
Vanderburg, A. et al. A disintegrating minor planet transiting a white dwarf. Nature 526, 546–549 (2015).
Koester, D., Gänsicke, B. T. & Farihi, J. The frequency of planetary debris around young white dwarfs. Astron. Astrophys. 566, A34 (2014).
Jura, M. A tidally disrupted asteroid around the white dwarf G29–38. Astrophys. J. 584, L91–L94 (2003).
Zuckerman, B., Koester, D., Melis, C., Hansen, B. M. & Jura, M. The chemical composition of an extrasolar minor planet. Astrophys. J. 671, 872–877 (2007).
Frewen, S. F. N. & Hansen, B. M. S. Eccentric planets and stellar evolution as a cause of polluted white dwarfs. Mon. Not. R. Astron. Soc. 439, 2442–2458 (2014).
Xu, S. et al. The chemical composition of an extrasolar Kuiper Belt Object. Astrophys. J. 836, L7 (2017).
Gentile Fusillo, N. P., Gänsicke, B. T. & Greiss, S. A photometric selection of white dwarf candidates in Sloan Digital Sky Survey Data Release 10. Mon. Not. R. Astron. Soc. 448, 2260–2274 (2015).
Horne, K. & Marsh, T. R. Emission line formation in accretion discs. Mon. Not. R. Astron. Soc. 218, 761–773 (1986).
Gänsicke, B. T., Marsh, T. R., Southworth, J. & Rebassa-Mansergas, A. A gaseous metal disk around a white dwarf. Science 314, 1908–1910 (2006).
Melis, C. et al. Gaseous material orbiting the polluted, dusty white dwarf HE 1349–2305. Astrophys. J. Lett. 751, 4 (2012).
Bauer, E. B. & Bildsten, L. Polluted white dwarfs: mixing regions and diffusion timescales. Astrophys. J. 872, 96 (2019).
Ferland, G. J. et al. The 2017 release Cloudy. Rev. Mex. Astron. Astrofis. 53, 385–438 (2017).
Pyrzas, S. et al. Post-common envelope binaries from SDSS. XV. Accurate stellar parameters for a cool 0.4 M☉ white dwarf and a 0.16 M☉ M dwarf in a 3 h eclipsing binary. Mon. Not. R. Astron. Soc. 419, 817–826 (2012).
Davidsson, B. J. R. Tidal splitting and rotational breakup of solid spheres. Icarus 142, 525–535 (1999).
Gänsicke, B. T. et al. The chemical diversity of exo-terrestrial planetary debris around white dwarfs. Mon. Not. R. Astron. Soc. 424, 333–347 (2012).
de Pater, I., Romani, P. N. & Atreya, S. K. Uranus deep atmosphere revealed. Icarus 82, 288–313 (1989).
Irwin, P. G. J. et al. Detection of hydrogen sulfide above the clouds in Uranus’s atmosphere. Nat. Astron. 2, 420–427 (2018).
Irwin, P. G. J. et al. Probable detection of hydrogen sulphide (H2S) in Neptune’s atmosphere. Icarus 321, 550–563 (2019).
Ehrenreich, D. et al. A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b. Nature 522, 459–461 (2015).
Bourrier, V. et al. Hubble PanCET: an extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470b. Astron. Astrophys. 620, A147 (2018).
Tu, L., Johnstone, C. P., Güdel, M. & Lammer, H. The extreme ultraviolet and X-ray sun in time: high-energy evolutionary tracks of a solar-like star. Astron. Astrophys. 577, L3 (2015).
Hartman, J. D. et al. HAT-P-26b: a low-density Neptune-mass planet transiting a K star. Astrophys. J. 728, 138 (2011).
Wakeford, H. R. et al. HAT-P-26b: a Neptune-mass exoplanet with a well-constrained heavy element abundance. Science 356, 628–631 (2017).
Nelemans, G. & Tauris, T. M. Formation of undermassive single white dwarfs and the influence of planets on late stellar evolution. Astron. Astrophys. 335, L85–L88 (1998).
Mustill, A. J., Villaver, E., Veras, D., Gänsicke, B. T. & Bonsor, A. Unstable low-mass planetary systems as drivers of white dwarf pollution. Mon. Not. R. Astron. Soc. 476, 3939–3955 (2018).
Gentile Fusillo, N. P. et al. A Gaia Data Release 2 catalogue of white dwarfs and a comparison with SDSS. Mon. Not. R. Astron. Soc. 482, 4570–4591 (2019).
Manser, C. J. et al. Doppler imaging of the planetary debris disc at the white dwarf SDSS J122859.93+104032.9. Mon. Not. R. Astron. Soc. 455, 4467–4478 (2016).
McDonough, W. The composition of the Earth. In Earthquake Thermodynamics and Phase Transformation in the Earth’s Interior (eds Teisseyre, R. & Majewski, E.) 5–24 (Elsevier Science Academic Press, 2000).
Abazajian, K. N. et al. The Seventh Data Release of the Sloan Digital Sky Survey. Astrophys. J. Suppl. 182, 543–558 (2009).
Abolfathi, B. et al. The Fourteenth Data Release of the Sloan Digital Sky Survey: first spectroscopic data from the Extended Baryon Oscillation Spectroscopic Survey and from the Second Phase of the Apache Point Observatory Galactic Evolution Experiment. Astrophys. J. Suppl. 235, 42 (2018).
Vernet, J. et al. X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope. Astron. Astrophys. 536, A105 (2011).
Freudling, W. et al. Automated data reduction workflows for astronomy. The ESO Reflex environment. Astron. Astrophys. 559, A96 (2013).
Smak, J. On the emission lines from rotating gaseous disks. Acta Astron. 31, 395–408 (1981).
Koester, D. White dwarf spectra and atmosphere models. Mem. Soc. Astron. Ital. 81, 921–931 (2010).
Bergeron, P., Saffer, R. A. & Liebert, J. A spectroscopic determination of the mass distribution of DA white dwarfs. Astrophys. J. 394, 228–247 (1992).
Homeier, D. et al. An analysis of DA white dwarfs from the Hamburg quasar survey. Astron. Astrophys. 338, 563–575 (1998).
Schlafly, E. F. & Finkbeiner, D. P. Measuring reddening with Sloan Digital Sky Survey stellar spectra and recalibrating SFD. Astrophys. J. 737, 103 (2011).
Bergeron, P., Fontaine, G., Tremblay, P.-E. & Kowalski, P. M. Synthetic colors and evolutionary sequences of hydrogen- and helium-atmosphere white dwarfs (2016). http://www.astro.umontreal.ca/bergeron/CoolingModels/.
Holberg, J. B. & Bergeron, P. Calibration of synthetic photometry using DA white dwarfs. Astron. J. 132, 1221–1233 (2006).
Kowalski, P. M. & Saumon, D. Found: the missing blue opacity in atmosphere models of cool hydrogen white dwarfs. Astrophys. J. Lett. 651, 137–140 (2006).
Tremblay, P.-E., Bergeron, P. & Gianninas, A. An improved spectroscopic analysis of DA white dwarfs from the Sloan Digital Sky Survey Data Release 4. Astrophys. J. 730, 128 (2011).
Tremblay, P.-E. et al. Core crystallization and pile-up in the cooling sequence of evolving white dwarfs. Nature 565, 202–205 (2019).
Genest-Beaulieu, C. & Bergeron, P. A comprehensive spectroscopic and photometric analysis of DA and DB white dwarfs from SDSS and Gaia. Astrophys. J. 871, 169 (2019).
Bailer-Jones, C. A. L., Rybizki, J., Fouesneau, M., Mantelet, G. & Andrae, R. Estimating distance from parallaxes. IV. Distances to 1.33 billion stars in Gaia Data Release 2. Astron. J. 156, 58 (2018).
Bianchi, L. et al. Catalogues of hot white dwarfs in the Milky Way from GALEX’s ultraviolet sky surveys: constraining stellar evolution. Mon. Not. R. Astron. Soc. 411, 2770–2791 (2011).
Cummings, J. D., Kalirai, J. S., Tremblay, P.-E., Ramirez-Ruiz, E. & Choi, J. The white dwarf initial-final mass relation for progenitor stars from 0.85 to 7.5 M☉. Astrophys. J. 866, 21 (2018).
Kalirai, J. S. et al. The initial-final mass relation: direct constraints at the low-mass end. Astrophys. J. 676, 594–609 (2008).
Weidemann, V. Revision of the initial-to-final mass relation. Astron. Astrophys. 363, 647–656 (2000).
Catalán, S. et al. The initial-final mass relationship from white dwarfs in common proper motion pairs. Astron. Astrophys. 477, 213–221 (2008).
Casewell, S. L. et al. High-resolution optical spectroscopy of Praesepe white dwarfs. Mon. Not. R. Astron. Soc. 395, 1795–1804 (2009).
Williams, K. A., Bolte, M. & Koester, D. Probing the lower mass limit for supernova progenitors and the high-mass end of the initial-final mass relation from white dwarfs in the open cluster M35 (NGC 2168). Astrophys. J. 693, 355–369 (2009).
Hinkel, N. R., Timmes, F. X., Young, P. A., Pagano, M. D. & Turnbull, M. C. Stellar abundances in the solar neighborhood: the Hypatia Catalog. Astron. J. 148, 54 (2014).
Chayer, P. et al. Improved calculations of the equilibrium abundances of heavy elements supported by radiative levitation in the atmospheres of hot DA white dwarfs. Astrophys. J. 454, 429–441 (1995).
Deal, M., Deheuvels, S., Vauclair, G., Vauclair, S. & Wachlin, F. C. Accretion from debris disks onto white dwarfs. Fingering (thermohaline) instability and derived accretion rates. Astron. Astrophys. 557, L12 (2013).
Bauer, E. B. & Bildsten, L. Increases to inferred rates of planetesimal accretion due to thermohaline mixing in metal-accreting white dwarfs. Astrophys. J. Lett. 859, 19 (2018).
Hartmann, S., Nagel, T., Rauch, T. & Werner, K. Non-LTE models for the gaseous metal component of circumstellar discs around white dwarfs. Astron. Astrophys. 530, A7 (2011).
Melis, C., Jura, M., Albert, L., Klein, B. & Zuckerman, B. Echoes of a decaying planetary system: the gaseous and dusty disks surrounding three white dwarfs. Astrophys. J. 722, 1078–1091 (2010).
Kinnear, T. Irradiated Gaseous Discs Around White Dwarfs. Master’s thesis, Univ. of Warwick (2011).
Grevesse, N., Asplund, M., Sauval, A. J. & Scott, P. The chemical composition of the Sun. Astrophys. Space Sci. 328, 179–183 (2010).
Frank, J., King, A. & Raine, D. J. Accretion Power in Astrophysics 3rd edn (Cambridge University Press, 2002).
Marsh, T. R. LTE models of the emission lines of the dwarf nova Z Cha. Mon. Not. R. Astron. Soc. 228, 779–796 (1987).
Szkody, P. et al. Cataclysmic variables from Sloan Digital Sky Survey. VI. The sixth year (2005). Astron. J. 134, 185–194 (2007).
Szkody, P. et al. Finding the instability strip for accreting pulsating white dwarfs from Hubble Space Telescope and optical observations. Astrophys. J. 710, 64–77 (2010).
Breedt, E. et al. 1000 cataclysmic variables from the Catalina Real-Time Transient Survey. Mon. Not. R. Astron. Soc. 443, 3174–3207 (2014).
Thorstensen, J. R., Alper, E. H. & Weil, K. E. A trip to the cataclysmic binary zoo: detailed follow-up of 35 recently discovered systems. Astron. J. 152, 226 (2016).
Gänsicke, B. T. et al. Sdss unveils a population of intrinsically faint cataclysmic variables at the minimum orbital period. Mon. Not. R. Astron. Soc. 397, 2170–2188 (2009).
Pala, A. F. et al. Effective temperatures of cataclysmic-variable white dwarfs as a probe of their evolution. Mon. Not. R. Astron. Soc. 466, 2855–2878 (2017).
Hillwig, T. C., Honeycutt, R. K. & Robertson, J. W. Post-common-envelope binary stars and the precataclysmic binary PG 1114+187. Astron. J. 120, 1113–1119 (2000).
Kawka, A., Vennes, S., Dupuis, J. & Koch, R. The 0.33 day DA plus dME binary BPM 6502. Astron. J. 120, 3250–3254 (2000).
O’Donoghue, D. et al. The DA+dMe eclipsing binary EC13471-1258: its cup runneth over… just. Mon. Not. R. Astron. Soc. 345, 506–528 (2003).
Schmidt, G. D., Smith, P. S., Harvey, D. A. & Grauer, A. D. The precataclysmic variable GD 245. Astron. J. 110, 398–404 (1995).
Aungwerojwit, A. et al. HS 1857+5144: a hot and young pre-cataclysmic variable. Astron. Astrophys. 469, 297–305 (2007).
Maxted, P. F. L., Napiwotzki, R., Dobbie, P. D. & Burleigh, M. R. Survival of a brown dwarf after engulfment by a red giant star. Nature 442, 543–545 (2006).
Parsons, S. G. et al. Testing the white dwarf mass-radius relationship with eclipsing binaries. Mon. Not. R. Astron. Soc. 470, 4473–4492 (2017).
Nebot Gómez-Morán, A. et al. Post common envelope binaries from SDSS. XII. The orbital period distribution. Astron. Astrophys. 536, A43 (2011).
Dye, S. et al. The UKIRT Hemisphere Survey: definition and J-band data release. Mon. Not. R. Astron. Soc. 473, 5113–5125 (2018).
Hoard, D. W. et al. Cool companions to white dwarf stars from the Two Micron All Sky Survey All Sky Data Release. Astron. J. 134, 26–42 (2007).
Debes, J. H. & Measuring, M. Dwarf winds with DAZ white dwarfs. Astrophys. J. 652, 636–642 (2006).
Tappert, C., Gänsicke, B. T., Rebassa-Mansergas, A., Schmidtobreick, L. & Schreiber, M. R. Multiple emission line components in detached post-common-envelope binaries. Astron. Astrophys. 531, A113 (2011).
Eggleton, P. P. Approximations to the radii of Roche lobes. Astrophys. J. 268, 368–369 (1983).
Owen, J. E. Atmospheric escape and the evolution of close-in exoplanets. Annu. Rev. Earth Planet. Sci. 47, 67–90 (2019).
Vidal-Madjar, A. et al. An extended upper atmosphere around the extrasolar planet HD209458b. Nature 422, 143–146 (2003).
Lecavelier des Etangs, A. et al. Evaporation of the planet HD 189733b observed in H I Lyman-α. Astron. Astrophys. 514, A72 (2010).
Kulow, J. R., France, K., Linsky, J. & Loyd, R. O. P. Lyα transit spectroscopy and the neutral hydrogen tail of the hot Neptune GJ 436b. Astrophys. J. 786, 132 (2014).
Lavie, B. et al. The long egress of GJ 436b’s giant exosphere. Astron. Astrophys. 605, L7 (2017).
Vidal-Madjar, A. et al. Magnesium in the atmosphere of the planet HD 209458 b: observations of the thermosphere-exosphere transition region. Astron. Astrophys. 560, A54 (2013).
Ben-Jaffel, L. & Ballester, G. E. Hubble Space Telescope detection of oxygen in the atmosphere of exoplanet HD 189733b. Astron. Astrophys. 553, A52 (2013).
Poppenhaeger, K., Schmitt, J. H. M. M. & Wolk, S. J. Transit observations of the hot Jupiter HD 189733b at X-ray wavelengths. Astrophys. J. 773, 62 (2013).
Murray-Clay, R. A., Chiang, E. I. & Murray, N. Atmospheric escape from hot Jupiters. Astrophys. J. 693, 23–42 (2009).
Chayer, P., Fontaine, G. & Wesemael, F. Radiative levitation in hot white dwarfs: equilibrium theory. Astrophys. J. Suppl. 99, 189–221 (1995).
Owen, J. E. & Alvarez, M. A. UV driven evaporation of close-in planets: energy-limited, recombination-limited, and photon-limited flows. Astrophys. J. 816, 34 (2015).
Erkaev, N. V. et al. Roche lobe effects on the atmospheric loss from “hot Jupiters”. Astron. Astrophys. 472, 329–334 (2007).
Schwadron, N. A. et al. Solar radiation pressure and local interstellar medium flow parameters from Interstellar Boundary Explorer low energy hydrogen measurements. Astrophys. J. 775, 86 (2013).
Bzowski, M. et al. Solar parameters for modeling the interplanetary background. In Cross-Calibration of Far UV Spectra of Solar System Objects and the Heliosphere (eds Quémerais, E., et al.) 67 (ISSI Scientific Report Series 13, 2013).
McClintock, W. E., Rottman, G. J. & Woods, T. N. Solar-Stellar Irradiance Comparison Experiment II (Solstice II): instrument concept and design. Sol. Phys. 230, 225–258 (2005).
Valsecchi, F., Rappaport, S., Rasio, F. A., Marchant, P. & Rogers, L. A. Tidally-driven Roche-lobe overflow of hot Jupiters with MESA. Astrophys. J. 813, 101 (2015).
Bashi, D., Helled, R., Zucker, S. & Mordasini, C. Two empirical regimes of the planetary mass-radius relation. Astron. Astrophys. 604, A83 (2017).
Farihi, J., Parsons, S. G. & Gänsicke, B. T. A circumbinary debris disk in a polluted white dwarf system. Nat. Astron. 1, 0032 (2017).
Soker, N. Can planets influence the horizontal branch morphology? Astron. J. 116, 1308–1313 (1998).
Dewi, J. D. M. & Tauris, T. M. On the energy equation and efficiency parameter of the common envelope evolution. Astron. Astrophys. 360, 1043–1051 (2000).
Zorotovic, M. et al. Post common envelope binaries from SDSS. XIII. Mass dependencies of the orbital period distribution. Astron. Astrophys. 536, L3 (2011).
Hurley, J. R., Tout, C. A. & Pols, O. R. Evolution of binary stars and the effect of tides on binary populations. Mon. Not. R. Astron. Soc. 329, 897–928 (2002).
Zorotovic, M., Schreiber, M. R., Gänsicke, B. T. & Nebot Gómez-Morán, A. Post-common-envelope binaries from SDSS. IX: constraining the common-envelope efficiency. Astron. Astrophys. 520, A86 (2010).
Borgniet, S. et al. Extrasolar planets and brown dwarfs around AF-type stars. X. the SOPHIE sample: combining the SOPHIE and HARPS surveys to compute the close giant planet mass-period distribution around AF-type stars. Astron. Astrophys. 621, A87 (2019).
Veras, D. & Gänsicke, B. T. Detectable close-in planets around white dwarfs through late unpacking. Mon. Not. R. Astron. Soc. 447, 1049–1058 (2015).
Thorngren, D. & Fortney, J. J. Connecting giant planet atmosphere and interior modeling: constraints on atmospheric metal enrichment. Astrophys. J. Lett. 874, L31 (2019).
Fontaine, G., Brassard, P. & Bergeron, P. The potential of white dwarf cosmochronology. Publ. Astron. Soc. Pacif. 113, 409–435 (2001).
Funding for the Sloan Digital Sky Survey IV was provided by the Alfred P. Sloan Foundation, the US Department of Energy Office of Science, and the Participating Institutions. The SDSS website is www.sdss.org. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 0102.C-0351(A). B.T.G. and C.J.M. were supported by the UK STFC grant ST/P000495. M.R.S. acknowledges support from the Millennium Nucleus for Planet Formation (NPF) and Fondecyt (grant 1181404). O.T. was supported by a Leverhulme Trust Research Project Grant. The research leading to these results has received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme number 677706 (WD3D).
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Peer review information Nature thanks Patrick Dufour and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Extended data figures and tables
The unusual nature of WD J0914+1914 was identified from its optical spectrum within SDSS Data Release 14. The Hα, O i 7,774 Å and O i 8,446 Å lines are clearly detected, S [ii] 4,068 Å and a blend of S i and O i near 9,240 Å are present near the noise level.
The double-peaked emission lines of hydrogen (a), oxygen (b, c, e, f) and sulfur (d) detected in the optical spectrum of WD J0914+1914 originate in a gaseous circumstellar disk. Shown in red are synthetic disk profiles computed by convolving the Cloudy model that best matches the observed line flux ratios with the broadening function of a Keplerian disk. Adopting an inclination of i = 60°, the widths and double-peak separations of the Hα (a) and O i 8,446 Å (c) lines are well reproduced for inner and outer disk radii of rin ≈ (1.0–1.3)R⊙ and rout ≈ (2.8–3.3)R⊙, respectively, consistent with the results from the Cloudy models (see Extended Data Fig. 4). The emission of [S ii] 4,068 Å (d) extends from about 1R⊙ to 10R⊙. The V-shaped central depression of the O i 8,446 Å (c) line suggests that the line is optically thick.
Extended Data Fig. 3 Dynamical constraints on the location of the circumstellar gas emitting the observed double-peaked emission lines.
The gas in the circumstellar disk follows Keplerian orbits, and hence the profile shape of the observed emission lines (see Fig. 1 and Extended Data Fig. 2) encodes the location of the gas. The velocity separation of the double-peaks and the maximum velocity in the line wings correspond to motion of gas at the outer edge and inner edge of the disk, respectively. For a given inclination of the disk, these velocities map into semi-major axes. A lower limit on the inclination, i > 5°, arises from the finite size of the white dwarf (Rwd), and an upper limit on the extent of the disk is provided for an edge-on, i = 90°, inclination. The forbidden [S ii] 4,068 Å line has a much smaller separation of the double-peaks compared to Hα and O i 8,446 Å, implying a larger radial extent.
The line flux ratios of a grid of Cloudy models spanning a range of gas densities, ρ, and radial distances from the white dwarf, r, from the white dwarf are compared to the observed values. The two histograms show the average quality for constant r (top) and constant ρ (right). The observed emission line fluxes are reasonably well reproduced by photo-ionized gas with a density of ρ = 10−11.3 g cm−3 and located at about (1–4)R⊙.
a, Comparison of the irradiating EUV flux around T Tauri stars (yellow-shaded region) and that of WD J0914+1914 (red line). The outer border of the warm Neptune desert is indicated by the vertical dashed line. The orbital separation of the planet orbiting WD J0914+1914 estimated from the size of the accretion disk is about (14–16)R⊙ (grey-shaded region). Subject to an EUV luminosity comparable to that of planets around T Tauri stars, the giant planet at WD J0914+1914 is well within the warm Neptune desert. b, Mass loss rates estimated from the assumption of recombination and energy limited hydrodynamic escape for a Jupiter mass and a Neptune mass planet. Substantial mass loss could be generated even for separations of up to a few hundred solar radii, well beyond the estimated orbital location of the giant planet at WD J0914+1914.
a, Lyα irradiance of the Sun across a full solar activity cycle as measured by the SORCE SOLSTICE instrument. The radiation pressure on neutral interplanetary hydrogen in the solar system usually exceeds the gravitational force exerted by the Sun. b, The Lyα flux of the Sun during minimum (2008) and maximum (2014) in comparison to the emission of WD J0914+1914 at a distance of 15R⊙. Given that WD J0914+1914 is less massive than the Sun, and that its Lyα flux is comparable to that of the Sun in the core of the line, but much larger in the wings (even during the 2014 solar maximum), radiation pressure strongly impedes the inflow of hydrogen, explaining the large depletion of hydrogen with respect to oxygen and sulfur within the circumstellar disk.
Extended Data Fig. 7 Final separation after common envelope evolution as a function of planetary mass.
We adopted two common envelope efficiencies, α = 0.25 (solid line), and α = 1.0 (dashed line) to calculate an upper limit for the final separation (afinal) if the progenitor of WD J0914+1914 and the planet evolved through a common envelope phase. The parameter space of possible outcomes of common envelope evolution lies below these lines (grey-shaded region). We consider the smaller efficiency to be more realistic. For configurations below the red line (aphot), the planetary mass object will evaporate inside the giant envelope; below the blue line (aRL), it would overflow its Roche lobe. Only planets with parameters within the green-shaded region can survive common envelope evolution. Whereas common envelope evolution can bring a Jupiter-mass planet to the estimated location of the planet around WD J0914+1914 (at (14–16)R⊙), smaller planets will be evaporated in the giant envelope.
White dwarfs cool with time and as a consequence their EUV luminosity decreases. We calculated model spectra for effective temperatures from 80,000 K to 10,000 K, integrated the EUV flux, and determined the mass loss rate of a Jupiter and a Neptune at a distance of 10R⊙. At a cooling age of 364 million years the white dwarf will have cooled down to 12,000 K, the mass loss rate will drop below about 106 g s−1, and the resulting photospheric contamination by oxygen and sulfur will become undetectable. Integrating the mass loss rate over the entire cooling time results in a total mass loss of about 0.002MJup, which corresponds to about 3.7% of the mass of Neptune.