On The Existence of Planets Around the Pulsar PSR B0329+54

On The Existence of Planets Around the Pulsar PSR B0329+54 

Authors:

Starovoit et al

Abstract: 

Results of timing measurements of the pulsar PSR B0329+54 obtained in 1968--2012 using the Big Scanning Antenna of the Pushchino Radio Astronomy Observatory (at 102 and 111 MHz), the DSS 13 and DSS 14 telescopes of the Jet Propulsion Laboratory (2388 MHz), and the 64 m telescope of the Kalyazin Radio Astronomy Observatory (610 MHz) are presented. The astrometric and rotational parameters of the pulsar are derived at a new epoch. Periodic variations in the barycentric timing residuals have been found, which can be explained by the presence of a planet orbiting the pulsar, with an orbital period P1 = 27.8 yr, mass \textit{mc}sin\textit{i} = 2M⊕, and orbital semi-major axis a = 10.26 AU. The results of this study do not confirm existence of a proposed second planet with orbital period P2 = 3 yr.

Could Exoplanets Around Neutron Stars be Habitable?

Neutron Star Planets: Atmospheric processes and habitability

Authors:

Patruno et al

Abstract: 

Of the roughly 3000 neutron stars known, only a handful have sub-stellar companions. The most famous of these are the low-mass planets around the millisecond pulsar B1257+12. New evidence indicates that observational biases could still hide a wide variety of planetary systems around most neutron stars. We consider the environment and physical processes relevant to neutron star planets, in particular the effect of X-ray irradiation and the relativistic pulsar wind on the planetary atmosphere. We discuss the survival time of planet atmospheres and the planetary surface conditions around different classes of neutron stars, and define a neutron star habitable zone. Depending on as-yet poorly constrained aspects of the pulsar wind, both Super-Earths around B1257+12 could lie within its habitable zone.

Why are pulsar planets rare?

Why are pulsar planets rare?

Authors:

Martin et al

Abstract:

Pulsar timing observations have revealed planets around only a few pulsars. We suggest that the rarity of these planets is due mainly to two effects. First, we show that the most likely formation mechanism requires the destruction of a companion star. Only pulsars with a suitable companion (with an extreme mass ratio) are able to form planets. Second, while a dead zone (a region of low turbulence) in the disk is generally thought to be essential for planet formation, it is most probably rare in disks around pulsars because of the irradiation from the pulsar. The irradiation strongly heats the inner parts of the disk pushing the inner boundary of the dead zone out. We suggest that the rarity of pulsar planets can be explained by the low probability for these two requirements - a very low-mass companion and a dead zone - to be satisfied.

Merger of a White Dwarf-Neutron Star Binary to 1029 Carat Diamonds: Origin of the Pulsar Planets

Merger of a White Dwarf-Neutron Star Binary to 1029 Carat Diamonds: Origin of the Pulsar Planets

Authors:

Margalit et al

Abstract:

We show that the merger and tidal disruption of a C/O white dwarf (WD) by a neutron star (NS) binary companion provides a natural formation scenario for the PSR B1257+12 planetary system. Starting with initial conditions for the debris disk produced of the disrupted WD, we model its long term viscous evolution, including for the first time the effects of mass and angular momentum loss during the early radiatively inefficient accretion flow (RIAF) phase and accounting for the unusual C/O composition on the disk opacity. For plausible values of the disk viscosity α∼10−3−10−2 and the RIAF mass loss efficiency, we find that the disk mass remaining near the planet formation radius at the time of solid condensation is sufficient to explain the pulsar planets. Rapid rocky planet formation via gravitational instability of the solid carbon-dominated disk is facilitated by the suppression of vertical shear instabilities due to the high solid-to-gas ratio. Additional evidence supporting a WD-NS merger scenario includes (1) the low observed occurrence rate of pulsar planets (≲1% of NS birth), comparable to the expected WD-NS merger rate; (2) accretion by the NS during the RIAF phase is sufficient to spin PSR B1257+12 up to its observed 6 ms period; (3) similar models of `low angular momentum' disks, such as those produced from supernova fallback, find insufficient mass reaching the planet formation radius. The unusually high space velocity of PSR B1257+12 of ≳326kms−1 suggests a possible connection to the Calcium-rich transients, dim supernovae which occur in the outskirts of their host galaxies and were proposed to result from mergers of WD-NS binaries receiving SN kicks. The C/O disk composition implied by our model likely results in carbon-rich planets with diamond interiors.

Determining the Composition of Pulsar Orbiting Super Jupiters With Radio Line Spectroscopy

Inferring the composition of super-Jupiter mass companions of pulsars with radio line spectroscopy

Authors:

Ray et al

Abstract:

We propose using radio line spectroscopy to detect molecular absorption lines (such as OH at 1.6-1.7 GHz) before and after the total eclipse of black widow (BW) and other short orbital period binary pulsars with low mass companions. The companion in such a binary may be ablated away by energetic particles and high energy radiation produced by the pulsar wind. The observations will probe the eclipsing wind being ablated by the pulsar and constrain the nature of the companion and its surroundings. Maser emission from the interstellar medium stimulated by a pulsar beam might also be detected from the intrabinary medium. The short temporal resolution allowed by the millisecond pulsars can probe this medium with the high angular resolution of the pulsar beam.

Limits on Exoplanet Formation Around Pulsars

Limits on Planet Formation Around Young Pulsars and Implications for Supernova Fallback Disks

Authors:

Kerr et al

Abstract:

We have searched a sample of 151 young, energetic pulsars for periodic variation in pulse time-of-arrival arising from the influence of planetary companions. We are sensitive to objects with masses two orders of magnitude lower than those detectable with optical transit timing, but we find no compelling evidence for pulsar planets. For the older pulsars most likely to host planets, we can rule out Mercury analogues in one third of our sample and planets with masses greater 0.4M⊕ and periods Pb less than 1 yr in all but 5% of such systems. If pulsar planets form primarily from supernova fallback disks, these limits imply that such disks do not form, are confined to less than 0.1 AU radii, are disrupted, or form planets more slowly (greater than 2 Myr) than their protoplanetary counterparts.