Accreting magnetars: a new type of high-mass X-ray binaries?

The discovery of very slow pulsations (Pspin =5560 s) has solved the long-standing question of the nature of the compact object in the high-mass X-ray binary 4U 2206+54 but has posed new ones. According to spin evolutionary models in close binary systems, such slow pulsations require a neutron star magnetic field strength larger than the quantum critical value of 4.4 × 1013 G, suggesting the presence of a magnetar. We present the first XMM–Newton observations of 4U 2206+54 and investigate its spin evolution. We find that the observed spin-down rate agrees with the magnetar scenario. We analyse Integral Spacecraft Gamma-Ray Imager (ISGRI)/INTErnational Gamma-RAy Laboratory (INTEGRAL) observations of 4U 2206+54 to search for the previously suggested cyclotron resonance scattering feature at ∼30 keV. We do not find a clear indication of the presence of the line, although certain spectra display shallow dips, not always at 30 keV. The association of these dips with a cyclotron line is very dubious because of its apparent transient nature. We also investigate the energy spectrum of 4U 2206+54 in the energy range 0.3–10 keV with unprecedented detail and report for the first time the detection of very weak 6.5 keV fluorescence iron lines. The photoelectric absorption is consistent with the interstellar value, indicating very small amount of local matter, which would explain the weakness of the florescence lines. The lack of matter locally to the source may be the consequence of the relatively large orbital separation of the two components of the binary. The wind would be too tenuous in the vicinity of the neutron star.

The evolution and masses of the neutron star and donor star in the high mass X-ray binary OAO 1657−415

We report near-infrared radial velocity (RV) measurements of the recently identified donor star in the high mass X-ray binary (HMXB) system OAO 1657−415 obtained in the H band using ISAAC on the Very Large Telescope. Cross-correlation methods were employed to construct a RV curve with a semi-amplitude of 22.1 ± 3.5 km s−1. Combined with other measured parameters of this system it provides a dynamically determined neutron star (NS) mass of 1.42 ± 0.26 M⊙ and a mass of 14.3 ± 0.8 M⊙ for the Ofpe/WN9 highly evolved donor star. OAO 1657−415 is an eclipsing HMXB pulsar with the largest eccentricity and orbital period of any within its class. Of the 10 known eclipsing X-ray binary pulsars OAO 1657−415 becomes the ninth with a dynamically determined NS mass solution and only the second in an eccentric system. Furthermore, the donor star in OAO 1657−415 is much more highly evolved than the majority of the supergiant donors in other HMXBs, joining a small but growing list of HMXBs donors with extensive hydrogen depleted atmospheres. Considering the evolutionary development of OAO 1657−415, we have estimated the binding energy of the envelope of the mass donor and find that there is insufficient energy for the removal of the donor’s envelope via spiral-in, ruling out a common envelope evolutionary scenario. With its non-zero eccentricity and relatively large orbital period the identification of a definitive evolutionary pathway for OAO 1657−415 remains problematic, we conclude by proposing two scenarios which may account for OAO 1657−415 current orbital configuration.

Notes on the Transactions of the Royal Society of London, undated

This folder contains four documents with undated notes about the College's holdings of the Philosophical Transactions of the Royal Society of London.

Hollis Hall or Stoughton Hall, ca. 1801

Detailed floor plan of either Hollis Hall or Stoughton Hall, as indicated on drawing. Includes dimensions for student chambers, hallways, and stairs.

Hollis Hall, Harvard College, Cambridge, Middlesex Co., Mass., Second Floor Plan, (photostat copy), [1934]

Partial photostat copy of Sheet 2 of 10.

A s.w. [south west] view of Mass. [Massachusetts] Hall, [1828]

Pencil drawing of South West view of Massachusetts Hall.

Stoughton Hall..N.W. [Northwest] View, 1827

Pen and ink drawing of a northwest view of Stoughton Hall, watermarked 1827

Stoughton Hall..S.E. [Southeast] View, 1827

Pen and ink drawing of a southeast view of Stoughton Hall, watermarked 1827

First Floor, Stoughton, 1874

Floor plan of renovations for the first floor of Stoughton Hall, as drawn by William Rotch Ware in 1874. Includes dimensions for student chambers, hallways, and coal furnaces.

Second Floor, Stoughton, 1874

Floor plan of renovations for the second floor of Stoughton Hall, as drawn by William Rotch Ware in 1874. Includes dimensions for student chambers, proctor's rooms, hallways, and coal furnaces.

Third Floor, Fourth Floor, Stoughton, 1874

Floor plan of renovations for the third and fourth floors of Stoughton Hall, as drawn by William Rotch Ware in 1874. Includes dimensions for student chambers, H.P. Club Rooms, hallways, and coal furnaces.

[Letter from Thomas Clap to Royal Tyler,] 1764 August 1

One-page handwritten letter from Thomas Clap to Royal Tyler acknowledging his return of "Mr. Sewals Hebrew Grammar" to Tyler and noting that the work is "best especially for beginners." The letter is torn into three pieces and some text is missing. A portion of the missing text can be found in Box 4.

Settlement of chambers, 1741-1764

The book is comprised of folio-sized pages conserved in a modern soft-cover binding. The volume consists of yearly handwritten lists of dormitory room assignments for the years 1741-1753 and 1761-1764. Students are listed by last name and building names are often abbreviated as "M" for Massachusetts Hall, "S" for Stoughton Hall, and "O" for Old College or Harvard Hall. The organizational pattern varies by list, some are alphabetical, others arranged by building and room number. The lists for 1743, 1748, 1749, 1761-1764 also note students living outside of the College and their locations. The lists for 1761-1764 also include the waiters and monitors for the academic year.

Student compositions of Washington Allston, 1799

Handwritten essay about procrastination and a poem celebrating spring composed by Washington Allston while he was an undergraduate at Harvard. The essay uses a story about a young Italian named Bernardo to discuss the consequences of procrastination. The essay is labeled “Allston Novem. ’99" and is titled with a quote from Edward Young's poem "The Complaint," “Procrastination is Theif [sic] of time.” Allston’s poem celebrates spring and incorporates Phillida and Corydon, two characters from Nicholas Breton’s poem “Phillida and Cordion.” The poem is titled with the verses, “Chief, lovely spring, in thee, and thy soft scenes, / The smiling God is seen” from James Thompson's poem “Spring.” The poem is labeled "Allston July 10, 1799."

Late-Holocene Mass Movements in High Arctic East Lake, Melville Island (Western Canadian Arctic Archipelago)

East Lake, located at Cape Bounty (Melville Island, Canadian High Arctic), was mapped using a high-resolution swath bathymetric sonar and a 12 kHz sub-bottom profiler, allowing for the first time the imaging of widespread occurrence of mass movement deposits (MMDs) in a Canadian High Arctic Lake. Mass movements occurred mostly on steep slopes located away from deltaic sedimentation. The marine to lacustrine transition in the sediment favours the generation of mass movements where the underlying massive mud appears to act as a gliding surface for the overlying varved deposits. Based on acoustic stratigraphy, we have identified at least two distinct events that triggered failures in the lake during the last 2000 years. The synchronicity of multiple failures and their widespread distribution suggest a seismic origin that could be related to the nearby Gustaf-Lougheed Arch seismic zone. Further sedimentological investigations on the MMDs are however required to confirm their age and origin.