No surviving evolved companions of the progenitor of SN 1006

Type Ia supernovae are thought to occur when a white dwarf made of carbon and oxygen accretes sufficient mass to trigger a thermonuclear explosion(1). The accretion could be slow, from an unevolved (main-sequence) or evolved (subgiant or giant) star(2,3) (the single-degenerate channel), or rapid, as the primary star breaks up a smaller orbiting white dwarf(3,4) (the double-degenerate channel). A companion star will survive the explosion only in the single-degenerate channel(5). Both channels might contribute to the production of type Ia supernovae(6,7), but the relative proportions of their contributions remain a fundamental puzzle in astronomy. Previous searches for remnant companions have revealed one possible case for SN 1572 (refs 8, 9), although that has been questioned(10). More recently, observations have restricted surviving companions to be small, main-sequence stars(11-13), ruling out giant companions but still allowing the single-degenerate channel. Here we report the results of a search for surviving companions of the progenitor of SN 1006 (ref. 14). None of the stars within 4 arc minutes of the apparent site of the explosion is associated with the supernova remnant, and we can firmly exclude all giant and subgiant stars from being companions of the progenitor. In combination with previous results, our findings indicate that fewer than 20 per cent of type Ia supernovae occur through the single-degenerate channel.

The discovery, monitoring and environment of SGR J1935+2154

We report on the discovery of a new member of the magnetar class, SGR J1935+2154, and on its timing and spectral properties measured by an extensive observational campaign carried out between 2014 July and 2015 March with Chandra and XMM–Newton (11 pointings). We discovered the spin period of SGR J1935+2154 through the detection of coherent pulsations at a period of about 3.24 s. The magnetar is slowing down at a rate of P˙=1.43(1)×10−11 s s−1 and with a decreasing trend due to a negative P¨ of −3.5(7) × 10−19 s s−2. This implies a surface dipolar magnetic field strength of ∼2.2 × 1014 G, a characteristic age of about 3.6 kyr and a spin-down luminosity Lsd ∼1.7 × 1034 erg s−1. The source spectrum is well modelled by a blackbody with temperature of about 500 eV plus a power-law component with photon index of about 2. The source showed a moderate long-term variability, with a flux decay of about 25 per cent during the first four months since its discovery, and a re-brightening of the same amount during the second four months. The X-ray data were also used to study the source environment. In particular, we discovered a diffuse emission extending on spatial scales from about 1 arcsec up to at least 1 arcmin around SGR J1935+2154 both in Chandra and XMM–Newton data. This component is constant in flux (at least within uncertainties) and its spectrum is well modelled by a power-law spectrum steeper than that of the pulsar. Though a scattering halo origin seems to be more probable we cannot exclude that part, or all, of the diffuse emission is due to a pulsar wind nebula.

The London and Edinburgh philosophical magazine and journal of science.

3rd ser. : v.10 (1837 : Jan.-June)

[ Warrant for the arrest of Samuel Gray for debt], 1769

A warrant for the arrest and sale of all assets of Gray who was found to owe another merchant Alexander Hill in a recent trial. Also includes appraisal of property by Fairfield and Salter and statement by Sheriff Cudworth.

Warrants from the governor and chief justice of New York, 1703-1704

Copies of warrants and writs concerning public unrest caused by an attempt to survey lands on Long Island in 1702.

Rawda al-Ushshaq (Garden of Lovers) of Arifi, with three paintings : manuscript, ca. 1560-1575

Artist unknown.

Government failure, opposition success? Electoral performance in Portugal and Italy at the time of the crisis. Jean Monnet Occasional Paper 05/2014

The costs of the crisis in Southern European countries have not been only economic but political. Economic crises tend to lead to government instability and termination while political challengers are expected to exploit this contingent window of opportunity to gain an advantage over incumbents in national elections. The current crisis seems to make no exception, looking at the results of the general elections recently held in Southern Europe. However, this did not always lead to a clear victory of the main opposition parties. In most of the elections, in fact, the incumbent parties’ loss did not coincide with the official opposition’s gain. The extreme case is represented by Italy, where both the outgoing government coalition led by Silvio Berlusconi – setting aside for the moment the technocratic phase – and its main challenger, the centre left coalition, ended up losing millions of voters and a new political force, the Five Star Movement, obtained about 25 per cent of votes. On the opposite side there is Portugal. Only in Portugal did the vote increase for the centre right PSD, in fact, exceed the incumbent socialists’ loss. The present work aims at exploring the factors which might account for this significant divergence between the two cases.

The EU internal market - a stake or a tool in European-Russian gas relations. OSW Commentary No. 54, 2011-06-24

Since 2010 we have observed a new quality in EU energy policy. It is related to the European Commission’s more or less direct engagement in the bilateral gas relations of a part of the new member states – Poland, Bulgaria and Lithuania – with Russia. Although the long term outcome of this activity of the EC is as yet unclear it seems to be important for several reasons. Firstly it might increase the possibilities of the enforcement of the EU’s directives liberalising the internal gas market and specifically their implementation in individual gas agreements with suppliers from third countries (Gazprom). The consistency and determination of the EC in this field may be decisive for the future direction and depth of the liberalisation of the EU gas market. Furthermore, present developments may lead to an increase in EU and specifically EC competence in the field of energy policy, especially its external dimension. So what lessons can we draw from recent Commission activities on the following issues: – Implementing EU gas market 2nd and 3rd liberalisation packages and their main provisions – EU energy policy and its external dimension – recent developments and the EU’s role – EU-Russia gas relations – where Russian and EU interests diverge.