A Be-type star with a black-hole companion

Stellar-mass black holes have all been discovered through X-ray emission, which arises from the accretion of gas from their binary companions (this gas is either stripped from low-mass stars or supplied as winds from massive ones). Binary evolution models also predict the existence of black holes accreting from the equatorial envelope of rapidly spinning Be-type stars1, 2, 3 (stars of the Be type are hot blue irregular variables showing characteristic spectral emission lines of hydrogen). Of the approximately 80 Be X-ray binaries known in the Galaxy, however, only pulsating neutron stars have been found as companions2, 3, 4. A black hole was formally allowed as a solution for the companion to the Be star MWC 656 (ref. 5; also known as HD 215227), although that conclusion was based on a single radial velocity curve of the Be star, a mistaken spectral classification6 and rough estimates of the inclination angle. Here we report observations of an accretion disk line mirroring the orbit of MWC 656. This, together with an improved radial velocity curve of the Be star through fitting sharp Fe ii profiles from the equatorial disk, and a refined Be classification (to that of a B1.5–B2 III star), indicates that a black hole of 3.8 to 6.9 solar masses orbits MWC 656, the candidate counterpart of the γ-ray source AGL J2241+4454 (refs 5, 6). The black hole is X-ray quiescent and fed by a radiatively inefficient accretion flow giving a luminosity less than 1.6 × 10−7 times the Eddington luminosity. This implies that Be binaries with black-hole companions are difficult to detect in conventional X-ray surveys.

On the formation and evolution of the first Be star in a black hole binary MWC 656

We find that the formation of MWC 656 (the first Be binary containing a black hole) involves a common envelope phase and a supernova explosion. This result supports the idea that a rapidly rotating Be star can emerge out of a common envelope phase, which is very intriguing because this evolutionary stage is thought to be too fast to lead to significant accretion and spin up of the B star. We predict ∼10–100 of B-BH binaries to currently reside in the Galactic disc, among which around 1/3 contain a Be star, but there is only a small chance to observe a system with parameters resembling MWC 656. If MWC 656 is representative of intrinsic Galactic Be-BH binary population, it may indicate that standard evolutionary theory needs to be revised. This would pose another evolutionary problem in understanding black hole (BH) binaries, with BH X-ray novae formation issue being the prime example. Future evolution of MWC 656 with an ∼5 M⊙ BH and with an ∼13 M⊙ main-sequence companion on an ∼60 d orbit may lead to the formation of a coalescing BH–NS (neutron star) system. The estimated Advanced LIGO/Virgo detection rate of such systems is up to ∼0.2 yr−1. This empirical estimate is a lower limit as it is obtained with only one particular evolutionary scenario, the MWC 656 binary. This is only a third such estimate available (after Cyg X-1 and Cyg X-3), and it lends additional support to the existence of so far undetected BH–NS binaries.

Almonastires y rábitas: espiritualidad islámica individual y defensa colectiva de la comunidad. Espiritualidad y geopolítica en los orígenes de Almonaster la Real

Primeramente se describe el ŷihād, su origen coránico, la escatología asociada y el derecho musulmán asociado al mismo, para acabar explicando cómo el espíritu colectivo y estatal del ŷihād evolucionó hacia la espiritualidad individual del ribāṭ en Al-Andalus. En la segunda parte se enumeran los topónimos al-Munastīr en la península Ibérica, asociados a construcciones eclesiásticas visigodas precedentes, y se explica la geopolítica de Almonaster la Real: en la vía romana que comunicaba Sevilla y Huelva por la montaña onubense con Beja, esta vía de origen romano se usó hasta fin del s. X. La vigilancia en época omeya de este itinerario esencial de comunicación con Portugal dio origen a este “lugar de ribāṭ” que fue Almonaster, fundado sobre restos tardorromanos precedentes.

Geochemistry of labile organic matter in sediments and interstitial waters of ODP Sites 107-651 and 107-653

Sediment and interstitial water from Sites 651 and 653 (ODP Leg 107) were investigated by organic geochemical methods to characterize labile organic compound classes (amino compounds and carbohydrates) and to evaluate their progressive diagenetic and thermal degradation in deep-sea sediments. Downhole distribution of dissolved organic carbon (DOC) appears related to redox zones associated with bacterial activity and of diagenetic recrystallization of biogenic tests and not so much to organic matter concentrations in ambient sediments. DOC ranges from 250 to 8300 µmol/L (3-100.1 ppm). Amino acids contribute 10%-0.3% of DOC; carbohydrates range from 78 to 5 µmol/L. Rate of degradation of amino acids by thermal effects and/or bacterial activity at both sites (significantly different in sedimentation rates: average 41 cm/1000 yr in the top 300 m at Site 651, average 3.9 cm/1000 yr in the Pliocene/Quaternary sequence at Site 653 to 220 mbsf) is more dependent on exposure time rather than on the depth within the sediment column. Variability in neutral, acidic, and basic amino acid fractions of total amino acids (with a range of 1.1-0.02 µmol/g sediment; up to 2.5% of organic carbon) varies with carbonate content and by differences in thermal stability of amino acids. Distribution patterns of monosaccharides are interpreted to result from differences in organic matter sources, sedimentation rates, and the degree of organic matter decomposition prior to and subsequent to burial. Total particulate carbohydrates range from 1.82 to 0.21 µmol/g sediment and contribute about 8% to the sedimentary organic matter. Investigation of trace metals in the interstitial waters did not show any correlation of either DOC, amino compounds, or carbohydrates.

When Malindy sings /

Medium brown (C58) diagonal fine rib cloth; green, red, cream and gilt floral and lattice panel, gilt lettering, signed "MA", i.e. Margaret Armstrong; motif repeated on spine in green and pink; t.e.g., untrimmed.

The practical American cook book, or, Practical and scientific cookery /

Publisher's advertisements on p. [1]-[12] (2nd group).

An easy and economical book of Jewish cookery : upon strictly orthodox principles /

Advertisements at beginning and end.

Kochbuch für israelitische Frauen : enthaltend die verschiedensten Koch- und Backarten, mit einer vollständigen Speisekarte sowie einer genauen Anweisung zur Einrichtung und Führung einer religiös-jüdischen Haushaltung /

Advertisements on endpapers.

The new American cook book : containing thousands of recipes, practical suggestions and methods for the household contributed by celebrated chefs and more than two hundred experienced housekeepers, who are recognized authorities in the culinary art, and covering every branch of cookery : with special directions for serving at table, also preserving, pickling, candy-making, etc. : presenting the most healthful, palatable, economical and approved use of the foods of the twentieth century.

Includes indexes.

Baldwin Locomotive Works : illustrated catalogue of locomotives /

"Sketch of the Baldwin Locomotive Works": p. 5-53.

The vicar of Wakefield : a tale /

Illustrations are 12 mounted photographs.

Phlēng yāo konlabot læ konlaʻaksō̜n : tǣng čhārưk thī Wat Phrachētuphon nai ratchakān thī 3.

Introduction by Prince Damrong: p. (1)-(32).

Majmūʻ mushtamil ʻalá sitt rasāʾil [microform] /taʾlīf Muḥammad Haqqī Nāzlī.

al-Sunūḥāt al-Makīyyah al-futūḥāt al-ḥaqīyah fī ādāb al-tijārah wa-al-kasb -- Asbāb al-qūwah min iḥsān al-qudrah fī ādāb al-akl wa-al-shurb -- Aḥkām al-madhāhib fī aṭwār al-luḥá wa-al-shawārib -- Tanbīh al-rasūl ʻalá taqṣīr al-dhuyūl -- Ṭibb al-Qurʾān ḥub al-raḥmān -- Tafhīm al-ikhwān tajwīd al-Qurʾān.

La Cristiada /

Mode of access: Internet.