Search for nearby stars among proper motion stars selected by optical-to-infrared photometry. I. Discovery of LHS 2090 at spectroscopic distance of d=6pc

We present the discovery of a previously unknown very nearby star - LHS 2090 at a distance of only d=6 pc. In order to find nearby (i.e. d < 25 pc) red dwarfs, we re-identified high proper motion stars ($\mu >$ 0.18 arcsec/yr) from the NLTT catalogue (Luyten \cite{luyten7980}) in optical Digitized Sky Survey data for two different epochs and in the 2MASS data base. Only proper motion stars with large $R-K_s$ colour index and with relatively bright infrared magnitudes ($K_s<10$) were selected for follow-up spectroscopy. The low-resolution spectrum of LHS 2090 and its large proper motion (0.79 arcsec/yr) classify this star as an M6.5 dwarf. The resulting spectroscopic distance estimate from comparing the infrared $JHK_s$ magnitudes of LHS 2090 with absolute magnitudes of M6.5 dwarfs is $6.0\pm1.1$ pc assuming an uncertainty in absolute magnitude of $\pm$0.4 mag.Comment: 3 pages, 1 figure, accepted for publication in Astronomy and Astrophysics Letter

SSSPM J1444-2019: an extremely high proper motion, ultracool subdwarf

We present the discovery of a new extreme high proper motion object (3.5 arcsec/year) which we classify as an ultracool subdwarf with [M/H] = -0.5. It has a formal spectral type of sdM9 but also shows L-type features: while the VO bands are completely absent, it exhibits extremely strong TiO absorption in its optical spectrum. With a radial velocity of about -160 km/s and a rough distance estimate of 16--24 pc, it is likely one of the nearest halo members crossing the Solar neighbourhood with a heliocentric space velocity of (U,V,W)=(-244,-256,-100)+/-(32,77,6) km/s.Comment: 4 pages, 4 figures (Fig.1a-d available as jpg files), accepted for publication in Astronomy & Astrophysics Letter

Month of birth influences survival up to age 105+: first results from the age validation study of German semi-supercentenarians

Using data from Germany, we examine if month of birth influences survival up to age 105. Since age reporting at the highest ages is notoriously unreliable we draw on age-validated information from a huge age validation project of 1487 alleged German semi-supercentenarians aged 105+. We use month of birth as an exogenous indicator for seasonal changes in the environment around the time of birth. We find that the seasonal distribution of birth dates changes with age. For 925 age-validated semi-supercentenarians the seasonality is more pronounced than at the time of their births (1880-1900). Among the December-born the relative risk of survival from birth to age 105+ is 16 per cent higher than the average, among the June-born, 23 per cent lower. The month-of-birth pattern in the survival risks of the German semi-supercentenarians resembles closely the month-of-birth pattern in remaining life expectancy at age 50 in Denmark.

Lifetime earnings and life expectancy

We estimate remaining life expectancy at age 65 using a very large sample of male German pensioners. Our analysis is entirely nonparametric. Furthermore, the data enable us to compare life expectancy in eastern and western Germany conditional on a measure of socio-economic status. Our findings show a lower bound of almost fifty percent (six years) on the difference in remaining life expectancy between the lowest and the highest socio-economic group considered. Within groups, we find similar values for East and West. Our analysis contributes to the literature in several aspects. First, Germany is clearly underrepresented in differential mortality studies. Second, we are able to use a novel measure of lifetime earnings as a proxy for socio-economic status that remains valid for retired people. Third, the comparison of eastern and western Germany may provide some interesting insights for transformation countries.Germany, life expectancy, pensioners, socio-economic differentials

Official population statistics and the Human Mortality Database estimates of populations aged 80+ in Germany and nine other European countries

A systematic comparison of the Human Mortality Database and official estimates of populations aged 80+ is presented. We consider statistical series for East and West Germany and also for Denmark, England and Wales, France, Finland, Hungary, the Netherlands, Russia, Sweden, and Switzerland. The Human Mortality Database (HMD, www.mortality.org) methodology relies on the methods of extinct and almost extinct generations. HMD estimates are precise if the quality of death data is high and the migration among the elderly is negligible. The comparisons between the HMD and the official populations are not fully appropriate for the 1990s since the HMD calculations are related to official population estimates. A significant overestimation of the male population aged 80+ and especially 90+ between the censuses of 1970 and 1987 was found in West Germany. The relative surplus of men aged 90+ increased from 5 to 20 percent, which expressed in absolute numbers indicates an increase from 2 to 10 thousand. In 1971-1987 the official death rates have fallen dramatically to implausibly low values. In 1987-88 death rates based on the official populations suddenly jumped to the HMD death rates due to the census re-estimation. In the 1990s an accelerated decrease in male death rates has resumed. Among other countries, the relative and absolute deviations from the HMD estimates were especially high in Russia, Hungary, and England and Wales. Regression analysis reveals common factors of the relative deviation from the HMD populations. The deviation tends to decrease with time, increase with age, be higher during inter-census periods than in census years, and to decrease after the introduction of population registers.age/aging, elderly, population estimates, quality of statistics, statistics

Search for nearby stars among proper motion stars selected by optical-to-infrared photometry. II. Two late M dwarfs within 10 pc

We have identified two late M dwarfs within 10 parsecs of the Sun, by cross-correlating the Luyten NLTT catalogue of stars with proper motions larger than 0.18 arcsec/yr, with objects lacking optical identification in the 2MASS data base. The 2MASS photometry was then combined with improved optical photometry obtained from the SuperCOSMOS Sky Surveys. The two objects (LP775-31 and LP655-48) have extremely red optical-to-infrared colours ((R-K)~7) and very bright infrared magnitudes (K_s<10): follow-up optical spectroscopy with the ESO 3.6-m telescope gave spectral types of M8.0 and M7.5 dwarfs, respectively. Comparison of their near-infrared magnitudes with the absolute magnitudes of known M8 and M7.5 dwarfs with measured trigonometric parallaxes yields spectroscopic distance estimates of 6.4+/-1.4 parsecs and 8.0+/-1.6 parsecs for LP775-31 and LP655-48, respectively. In contrast, Cruz & Reid (2002) recently determined spectral types of M6 for both objects, and commensurately larger distances of 11.3+/-1.3 parsecs and 15.3+/-2.6 parsecs. LP655-48 is also a bright X-ray source (1RXS J044022.8-053020). With only a few late M dwarfs previously known within 10 parsecs, these two objects represent an important addition to the census of the Solar neighbourhood.Comment: Astronomy & Astrophysics (Letters), in press; 5 pages, 1 figure, uses aa.cls version 5.

Assessing old-age long-term care using the concepts of healthy life expectancy and care duration: the new parameter "Long-Term Care-Free Life-Expectancy (LTCF)"

Achieving old ages is also connected with prevalence of illness and long-term care. With the introduction of the statutory long-term care insurance in 1996 and the long-term care statistics in 1999 research data of about 2.3 million people receiving long-term care benefits is available. Average life expectancy can be qualitatively divided into lifetime spent in good health and lifetime spent in long-term care dependence (average care duration). In Germany women’s and men’s average care duration amount 3.6 years respectively 2.1 years.Germany, ageing, laboratories, life expectancy

Shuttle Ground Operations Efficiencies/Technologies (SGOE/T) study. Volume 2: Ground Operations evaluation

The Ground Operations Evaluation describes the breath and depth of the various study elements selected as a result of an operational analysis conducted during the early part of the study. Analysis techniques used for the evaluation are described in detail. Elements selected for further evaluation are identified; the results of the analysis documented; and a follow-on course of action recommended. The background and rationale for developing recommendations for the current Shuttle or for future programs is presented

Hybrid Quantum Dot-2D Electron Gas Devices for Coherent Optoelectronics

We present an inverted GaAs 2D electron gas with self-assembled InAs quantum dots in close proximity, with the goal of combining quantum transport with quantum optics experiments. We have grown and characterized several wafers -- using transport, AFM and optics -- finding narrow-linewidth optical dots and high-mobility, single subband 2D gases. Despite being buried 500 nm below the surface, the dots are clearly visible on AFM scans, allowing precise localization and paving the way towards a hybrid quantum system integrating optical dots with surface gate-defined nanostructures in the 2D gas.Comment: 4 pages, 5 figures (color

New insights into the dust formation of oxygen-rich AGB stars

We observed the AGB stars S Ori, GX Mon and R Cnc with the MIDI instrument at the VLTI. We compared the data to radiative transfer models of the dust shells, where the central stellar intensity profiles were described by dust-free dynamic model atmospheres. We used Al2O3 and warm silicate grains. Our S Ori and R Cnc data could be well described by an Al2O3 dust shell alone, and our GX Mon data by a mix of an Al2O3 and a silicate shell. The best-fit parameters for S Ori and R Cnc included photospheric angular diameters Theta(Phot) of 9.7+/-1.0mas and 12.3+/-1.0mas, optical depths tau(V)(Al2O3) of 1.5+/-0.5 and 1.35+/-0.2, and inner radii R(in) of 1.9+/-0.3R(Phot) and 2.2+/-0.3R(Phot), respectively. Best-fit parameters for GX Mon were Theta(Phot)=8.7+/-1.3mas, tau(V)(Al2O3)=1.9+/-0.6, R(in)(Al2O3)=2.1+/-0.3R(Phot), tau(V)(silicate)=3.2+/-0.5, and R(in)(silicate)=4.6+/-0.2R(Phot). Our model fits constrain the chemical composition and the inner boundary radii of the dust shells, as well as the photospheric angular diameters. Our interferometric results are consistent with Al2O3 grains condensing close to the stellar surface at about 2 stellar radii, co-located with the extended atmosphere and SiO maser emission, and warm silicate grains at larger distances of about 4--5 stellar radii. We verified that the number densities of aluminum can match that of the best-fit Al2O3 dust shell near the inner dust radius in sufficiently extended atmospheres, confirming that Al2O3 grains can be seed particles for the further dust condensation. Together with literature data of the mass-loss rates, our sample is consistent with a hypothesis that stars with low mass-loss rates form primarily dust that preserves the spectral properties of Al2O3, and stars with higher mass-loss rate form dust with properties of warm silicates.Comment: 20 pages, 10 figure