1. STELLAR REMNANT PLANET INVENTORY Session 1.1 Neutron star planets - PDF document

1. STELLAR REMNANT PLANET INVENTORY Session 1.1 Neutron star planets Monday, January 23 PSR B1257+12 planets: status and future prospects Alex Wolszczan (Penn State University) I will summarize the current observational status of the PSR B1257+12 planets, 20 years after the announcement of their discovery. I will also discuss issues related to neutron star planet detectability with the pulsar timing technique. Where are the other pulsar-planet systems? Scott Ransom (National Radio Astronomy Observatory) It's been twenty years since the spectacular pulsar planetary system B1257+12 was announced. At the time, not even 20 millisecond pulsars had been timed consistently or precisely enough to be able to detect such systems. Since then, more than 150 millisecond pulsars have had precise timing solutions established, yet only a single additional pulsar- planet system has materialized: the very strange triple system B1620-26 in globular cluster M4. So where are the others? The simple answer is: they aren't there. However, there is at least one potential "new" pulsar planetary system around an "isolated" pulsar in the globular cluster NGC6440. Unfortunately, confirming that the anomalous timing behavior is really planets has been (so far) impossible. Over the next 5 years we expect the number of known millisecond pulsars to grow by almost a factor of two. Will we find more pulsar-planet systems? Or will B1257+12 continue to grow in its "exotic-ness"? The Puzzle of the Planet around PSR1620-26 Steinn Sigurdsson (Penn State University) I review the extraordinary exoplanet orbiting a binary pulsar in the globular cluster M4, including an update on the ongoing observing program and current status of the parameters of the system. I also briefly discuss the broader implications of the system and the prospects for planet in globular clusters. Transformation of a Star into a Planet in a Millisecond Pulsar Binary Matthew Bailes (Swinburne University of Technology) and the HTRU team We have discovered a very short orbital period pulsar binary that comprises of a millisecond pulsar and a Jupiter- mass planet. Roche Lobe considerations suggest that the density is >22 g/cc and that the star is the evolved core of the once-massive star that recycled the pulsar. Mass-radius relations suggest that this system may comprise of the core of a Carbon white dwarf that was once an ultra-compact low-mass X-ray binary and expanded until it reached its current mass at which time to spiral-out ceased leaving the system in its current configuration. Unlike the original Millisecond pulsar with planets, the transverse velocity of this system appears to be very low. Substellar companions around young neutron stars Bettina Posselt (Penn State University) Young neutron stars show often timing noise at radio frequencies and some are radio-quiet. It is therefore difficult to search for planets around these neutron stars by radio timing. However, substellar companions around young neutron stars are expected to be still warm enough for substantial thermal emission in the Near-Infrared. Since the

neutron stars are very faint in the NIR, direct imaging can unobstructively detect co-moving, warm companions. We will present the current state of our direct imaging campaign to search for substellar companions around nearby, young neutron stars and give a short outlook regarding this search with future observing facilities. Session 1.2 Subdwarf planets Monday, January 23 SdB Planets Roberto Silvotti (INAF - Osservatorio Astronomico di Torino) et al In this talk I will make a short review on sdB planets, in particular from an observational point of view, and I will present/discuss recent results from space (Kepler) and from ground based photometry. Small planets in tight orbits around a hot B subdwarf star Stephane Charpinet (Institut de Recherche en Astrophysique et Planétologie) We present the discovery, based on Kepler ultra-high precision photometry, of two small planet candidates orbiting very close to a hot B subdwarf star. This star is essentially the hot and compact He burning remnant of a former red- giant core left exposed by the loss of nearly all of the red-giant envelope. This discovery may then be the first documented case suggesting that planets can have a significant role in influencing the late stages of stellar evolution. Substellar companion candidates around two pulsating sdB stars Ronny Lutz (Institut für Astrophysik Göttingen) One possible formation scenario to explain the existence of single subdwarf B stars includes the presence of substellarcompanions. We search for substellar companions around two pulsating single sdB stars, HS 0444+0458 (V1636 Ori) and HS 0702+6043 (DW Lyn) by means of a timing method and O-C diagrams. The same data used to search for companions are also used to investigate the secular behavior of the pulsations and to directly measure evolutionary timescales for these objects, which turn out to be in the range of several Myr. The data taken within the EXOTIME program cover several tens of months and based on these long-term data we present the detection of a brown dwarf candidate and an exoplanet candidate around our two target stars. Close substellar companions and the formation of hot subdwarf stars Stephan Geier (University of Erlangen-Nuremberg, ECAP and Remeis-Sternwarte) It has been suggested that besides stellar companions, substellar objects in close orbits may be able to trigger mass loss in a common envelope phase and form hot subdwarfs (sdBs). In an ongoing project we search for close substellar companions combining time resolved high resolution spectroscopy with photometry and found some very good candidate systems with brown dwarf companions. One of these objects has a mass close to the planetary regime. The implications of these new results for the open question of sdB formation are discussed. Planets around Hot Subdwarf Stars, or Not? Richard A. Wade (Penn State University), Brad N. Barlow, Sandra E. Liss, We will discuss the pulsating sdB star CS 1246 and an eclipsing sdB+dM system, both of which show interesting variations in pulsation or eclipse arrival times, which may be interpreted as indicating the

presence of a planet. We do not claim detection of planets, however. Our main concern is to summarize the need to be cautious about such claims, to seek corroborating evidence, and to analyze other possibilities that may plausibly account for the timing signals in these systems. We emphasize in particular the possibility that a small eccentricity may be present, even in a post-common-evelope binary, and that apsidal motion can then induce a timing variation in the absence of a third body. A third body, may of course be responsible for the small eccentricity, but so may other dynamical causes. Can Life Develop in the Expanded Habitable Zone Around Red Giant Stars? W. C. Danchi (NASA Goddard Space Flight Center), J.-L. Menut, B. Lopez The distance between a star and its habitable zone, as well as its width, increases with time due to stellar evolution. Currently, there is no clear evidence as to when life actually formed on the Earth, but recent isotopic data suggest that life existed at least as early as 700 million years after the Earth was formed. Thus if life could form and evolve over time intervals of 500-1000 million years, then there could be habitable planets with life around red giant stars. For a 1 solar mass star, at the first stages of its post-main-sequence evolution, the temporal transit of the habitable zone is estimated to be 1 billion years at 2 AU and around 100 million years at 9 AU. For a 1 solar mass star, after the first ascent along the red giant branch and after the helium flash, there is a stable habitable zone from 7-22 AU for up to 1 billion years during quiescent He core burning. In an initial paper (Lopez, Schneider, & Danchi, ApJ, 2005) we discussed the evolution of the habitable zone for 1, 1.5, and 2 solar mass stars with solar metallicity, and presented results for time periods up to the first ascent along the red giant branch. For this presentation, we discuss the previous results as well as new work including the evolution of the habitable zone during the core He burning phase and the ascent along the asymptotic giant branch for stars from 0.8 to 2 solar masses and for a broad range of metallicities. Session 1.3 White dwarf planets Tuesday, January 24 Direct detection of substellar and planetary companions to white dwarfs Matt Burleigh (University of Leicester) I will present the latest results from our searches for planetary and brown dwarf companions to white dwarfs through direct imaging observations and photometric surveys, including some exciting recent discoveries. I will discuss the limits on the incidence of such objects at white dwarfs, and as companions to their progenitors. I will also look to future opportunities to investigate the population of substellar and planetary companions to white dwarfs. Search for giant planets around white dwarfs Hans Zinnecker (Deutsche SOFIA Institut (DSI) der Universität Stuttgart & NASA Ames Research Center) We review our NICMOS/HST NIR direct imaging search for resolved self-luminous giant planet companions around the 7 white dwarfs in the Hyades cluster as well as additional imaging observations of nearby field white dwarfs and their progenitors with ground-based NIR adaptive optics (VLT/NACO and Gemini-North/NIRI). We discuss the implications of the non-detections and the potential of future higher angular resolution and higher sensitivity direct imaging mid-IR searches with the JWST. We touch upon Spitzer (and Herschel) unresolved observations of infrared excess emission of putative giant planets around nearby white dwarfs within 2O pc.