RXJ0806.3+1527: a double degenerate binary with the shortest known orbital period (321s)

We carried out optical observations of the field of the X-ray pulsator RXJ0806.3+1527. A blue V=21.1 star was found to be the only object consistent with the X-ray position. VLT FORS spectra revealed a blue continuum with no intrinsic absorption lines. Broad (v~1500 km/s), low equivalent width (about -1/-6A) emission lines from the HeII Pickering series were clearly detected. B, V and R time-resolved photometry revealed the presence of about 15% pulsations at the 321s X-ray period, confirming the identification. These findings, together with the period stability and absence of any additional modulation in the 1min-5hr period range, argue in favour of the orbital interpretation of the 321s pulsations. The most likely scenario is thus that RXJ0806.3+1527 is a double degenerate system of the AM CVn class. This would make RXJ0806.3+1527 the shortest orbital period binary currently known and one of the best candidates for gravitational wave detection.Comment: Accepted for publication on A&A Letter

Twenty-four hours secretion pattern of serum estradiol in healthy prepubertal and pubertal boys as determined by a validated ultra-sensitive extraction RIA

<p>Abstract</p> <p>Background</p> <p>The role of estrogens in male physiology has become evident. However, clinically useful normative data for estradiol secretion in boys has not previously been established due to the insensitivity of current methods used in clinical routine. By use of a validated ultra-sensitive extraction RIA, our aim was to establish normative data from a group consisting of healthy boys in prepuberty and during pubertal development.</p> <p>Methods</p> <p>Sixty-two 24-hours serum profiles (6 samples/24 hours) were obtained from 44 healthy boys (ages; 7.2–18.6 years) during their pubertal development, classified into five stages: prepuberty (testis, 1–2 mL), early (testis, 3–6 mL), mid (testis, 8–12 mL), late-1 (testis,15–25 mL, not reached final height) and late-2 (testis,15–25 mL, reached final height). Serum estradiol was determined by an ultra- sensitive extraction radioimmunoassay with detection limit 4 pmol/L and functional sensitivity 6 pmol/L.</p> <p>Results</p> <p>Mean estradiol concentrations during 24-hours secretion increased from prepuberty (median: <4 (5–95 percentiles: <4 – 7) pmol/L) to early puberty (6 (<4 – 12 pmol/L) but then remained relatively constant until a marked increase between mid-puberty (8 (4 – 17) pmol/L) and late-1 (21 (12 – 37) pmol/L) puberty, followed by a slower increase until late-2 puberty (32 (20 – 47) pmol/L). The diurnal rhythm of serum estradiol was non-measurable in pre- and early puberty, but discerned in mid-puberty, and become evident in late pubertal stages with peak values at 0600 to 1000 h.</p> <p>Conclusion</p> <p>With the use of an ultra-sensitive extraction RIA, we have provided clinically useful normative data for estradiol secretion in boys.</p

Hsp70 chaperones: Cellular functions and molecular mechanism

Hsp70 proteins are central components of the cellular network of molecular chaperones and folding catalysts. They assist a large variety of protein folding processes in the cell by transient association of their substrate binding domain with short hydrophobic peptide segments within their substrate proteins. The substrate binding and release cycle is driven by the switching of Hsp70 between the low-affinity ATP bound state and the high-affinity ADP bound state. Thus, ATP binding and hydrolysis are essential in vitro and in vivo for the chaperone activity of Hsp70 proteins. This ATPase cycle is controlled by co-chaperones of the family of J-domain proteins, which target Hsp70s to their substrates, and by nucleotide exchange factors, which determine the lifetime of the Hsp70-substrate complex. Additional co-chaperones fine-tune this chaperone cycle. For specific tasks the Hsp70 cycle is coupled to the action of other chaperones, such as Hsp90 and Hsp100

LINC-NIRVANA observation preparation software: design and perspective

LINC-NIRVANA (LN) is a near-infrared German-Italian Fizeau (imaging) interferometer for the Large Binocular Telescope (LBT). The processing of observations for this complex instrument has to be prepared accurately, considering the constraints imposed by features of the instrument and scientific objectives. The LN Observation Preparation Software (LOPS) is developed at the Max Planck Institute for Astronomy in Heidelberg in order to provide the observers with a rich and efficient tool to create valid observation programs (OP) for the LN. This paper describes the design of LOPS and presents its current development status addressing the key components and critical aspects

The host galaxy and Fermi-LAT counterpart of HESS J1943+213

International audienceThe very-high energy (VHE, E > 100 GeV) gamma-ray sky shows diverse Galactic and extragalactic source populations. For some sources the astrophysical object class could not be identified so far. The nature (Galactic or extragalactic) of the VHE gamma-ray source HESS J1943+213 is explored. We specifically investigate the proposed near-infrared counterpart 2MASS J19435624+2118233 of HESS J1943+213 and investigate the implications of a physical association. We present K-band imaging from the 3.5 meter CAHA telescope of 2MASS J19435624+2118233. Furthermore, 5 years of Fermi-LAT data were analyzed to search for a high-energy (HE, 100 MeV <E< 100 GeV) counterpart. The CAHA observations revealed that the near-infrared counterpart is extended with an intrinsic half light radius of 2" - 2.5" . These observations also show a smooth, centrally concentrated light profile that is typical of a galaxy, and thus point toward an extragalactic scenario for the VHE gamma-ray source, assuming that the near-infrared source is the counterpart of HESS J1943+213. A high-Sersic index profile provides a better fit than an exponential profile, indicating that the surface brightness profile of 2MASS J19435624+2118233 follows that of a typical, massive elliptical galaxy more closely than that of a disk galaxy. With Fermi-LAT a HE counterpart is found with a power law spectrum above 1 GeV. This gamma-ray spectrum shows a rather sharp break between the HE and VHE regimes. The infrared and HE data strongly favor an extragalactic origin of HESS J1943+213 The source is most likely located at a redshift between 0.03 and 0.45 according to extension and EBL attenuation arguments