Related papers: On the most metal-poor PN and its binary central s…

We explore the metal-poor regime of the Galactic disk on the distribution of stars in the [$\alpha$/M]-$V_{\phi}$ plane, to identify the most metal-poor thin disk (MPTnD) stars belonging to the low-$\alpha$ sequence. Chemical abundances and…

The abundance patterns of metal-poor stars provide us a wealth of chemical information about various stages of the chemical evolution of the Galaxy. In particular, these stars allow us to study the formation and evolution of the elements…

We present our analysis of VLT/UVES and X-shooter observations of six very metal-poor stars, including four stars at [Fe/H]$\approx$$-3$ in the Fornax and Carina dwarf spheroidal (dSph) galaxies. To date, this metallicity range in these two…

We have recently identified the widest very low-mass binary (2M0126AB), consisting of an M6.5V and an M8V dwarf with a separation of ~5100 AU, which is twice as large as that of the second widest known system and an order of magnitude…

We have searched the WISE first data release for widely separated (<10,000AU) late T dwarf companions to Hipparcos and Gliese stars. We have discovered a new binary system containing a K-band suppressed T8p dwarf WISEP J1423+0116 and the…

We provide *lambda*6708 Li 1 measurements in 37 metal-poor stars, most of which are poorly-studied or have no previous measurements, from high-resolution and high-S/N spectroscopy obtained with the McDonald Observatory 2.1m and 2.7m…

We investigate FUSE spectra of three PG1159 stars and do not find any evidence for iron lines. From a comparison with NLTE models we conclude a deficiency of 1-1.5 dex. We speculate that iron was transformed into heavier elements. A soft…

SDSS J010448.46+153501.8 has previously been classified as an sdM9.5 subdwarf. However, its very blue $J-K$ colour ($-0.15 \pm 0.17$) suggests a much lower metallicity compared to normal sdM9.5 subdwarfs. Here, we re-classify this object as…

Six planetary nebulae (PN) are known in the Kepler space telescope field of view, three newly identified. Of the 5 central stars of PN with useful Kepler data, one, J193110888+4324577, is a short-period, post common envelope binary…

We critically discuss the recent observations of the binary system at the center of the bipolar planetary nebula Henize 2-428. We find that the proposed explanation of two equal-mass degenerate objects with a total mass larger than the…

We present detailed abundance observations of the metal-poor ([Fe/H] = --2.0) Galactic halo star BD+17 3248. We have detected gold in this star, for the first time in any halo star. We also detected a weak line at 3859.60 A in the spectrum…

In the course of our ongoing survey of faint planetary-nebula nuclei (PNNi), we obtained optical spectroscopy of the central star of the little-studied PN Kohoutek~1-9 (K 1-9). Its spectrum is found to be that of a G-type dwarf with strong…

Ultra-short period compact binaries are important sources of gravitational waves, which include e.g. the progenitors of type Ia supernovae or the progenitors of merger episodes that may lead to massive and magnetic single white dwarfs.…

The observation of a compact object with a mass of $2.50-2.67M_{\odot}$ on August 14, 2019, by the LIGO Scientific and Virgo collaborations (LVC) has the potential to improve our understanding of the supranuclear equation of state. While…

We report the detection of two planetary mass companions to the solar-type star HD 155358. The two planets have orbital periods of 195.0 and 530.3 days, with eccentricities of 0.11 and 0.18. The minimum masses for these planets are 0.89 and…

We report the discovery of PSR J1753-2240 in the Parkes Multibeam Pulsar Survey database. This 95-ms pulsar is in an eccentric binary system with a 13.6-day orbital period. Period derivative measurements imply a characteristic age in excess…

We have used the Green Bank Telescope to observe the millisecond pulsar PSR J0514-4002A on 43 occasions spread over 2 years. This 5-ms pulsar is located in the globular cluster NGC 1851; it belongs to a binary system and has a highly…

The shortest-period binary star system known to date, RX J0806.3+1527 (HM Cancri), has now been observed in the optical for more than two decades. Although it is thought to be a double degenerate binary undergoing mass transfer, an early…

We report discovery and characterization of a main-sequence G star orbiting a dark object with mass $1.90\pm 0.04 M_{\odot}$. The system was discovered via Gaia astrometry and has an orbital period of 731 days. We obtained multi-epoch RV…

Using the Giant Metrewave Radio Telescope (GMRT), we have discovered PSR J0514-4002A, a binary millisecond pulsar in the globular cluster NGC 1851. This pulsar has a rotational period of 4.99 ms and the most eccentric pulsar orbit yet…