The Be/X-ray binary SXP 1062 is of especial interest owing to the large spin period of the neutron star, its large spin-down rate, and the association with a supernova remnant constraining its age. This makes the source an important probe for accretion physics. To investigate the long-term evolution of the spin period and associated spectral variations, we performed an XMM-Newton target-of-opportunity observation of SXP 1062 during X-ray outburst. Spectral and timing analysis of the XMM-Newton data was compared with previous studies, as well as complementary Swift/XRT monitoring and optical spectroscopy with the SALT telescope were obtained. The spin period was measured to be Ps=(1071.01+/-0.16)s on 2012 Oct 14. The X-ray spectrum is similar to that of previous observations. No convincing cyclotron absorption features, which could be indicative for a high magnetic field strength, are found. The high-resolution RGS spectra indicate the presence of emission lines, which may not completely be accounted for by the SNR emission. The comparison of multi-epoch optical spectra suggest an increasing size or density of the decretion disc around the Be star. SXP 1062 showed a net spin-down with an average of dPs/dt=(2.27+/-0.44)s/yr over a baseline of 915 days.
High-resolution spectroscopy of NGC 6210, show that recombination line abundances of O^+2^ and Ne^+2^ are two to three times larger than forbidden line abundances, T_e_(O^+2^) is smaller than T_e_(N^+^) and possibly T_e_(S^+^), the ionized mass is ~0.07 M_{sun}_ and the progenitor zero-age main-sequence mass is 1.2-2 M_{sun}_. If electrons are in equilibrium, recombination lines are likely produced in a cold low-density medium. A photoionization model (cloudy 13.03) with a positive density gradient and two exciting sources, reproduced most of the optical spectrum, the temperature distribution of the nebula, HeII 4686/HeI 5876, [OII]3726/[OIII]5007 and [OII]3726/3729, but not the other density sensitive line ratios. Including fluorescence and recombination, we found good agreement with observed CII and CIII line intensities, OII and OIII model intensities which are 2.6 and 7.8 times smaller than observed and large erratic differences with observations in CIII, NII and NIII lines. UV and IR data suggest that [OII] emission is from a region ~6 times less dense than assumed by the model and that IR lines are produced in a medium where the density is ~1000/cm^3^. There may be a lower density medium beyond a dense ring described by the photoionization model, as well as a cold low-density component. A multicomponent model is required to reproduce the entire spectrum of NGC 6210.
V4332 Sgr is a red transient (red nova) whose eruption was observed in 1994. The remnant of the eruption shows a unique optical spectrum: strong emission lines of atomes and molecules superimposed on a M-type stellar spectrum. The stellar-like remnant is presumably embedded in a disc-like dusty envelope orientated almost face-on. The observed optical spectrum is supposed to result from interactions of the central-star radiation with dust and gas in the disc and outflows initiated in 1994. We have reduced and measured a high-resolution (R~40000) spectrum of V4332 Sgr obtained with VLT/UVES in April/May 2005. The spectrum comes from the ESO archives and is the best quality spectrum of the object ever obtained. We have identified and measured over 200 emission features belonging to 11 elements and 6 molecules. The continuous, stellar-like component can be classified as ~M3. The radial velocity of the object, as derived from narrow atomic emission line, is -75km/s. The interstellar reddening was estimated as being 0.35<E(B-V)<0.75. From radial velocities of interstellar absorption features in the NaI D lines we have estimated a lower limit of ~5.5 kpc to the distance of V4332 Sgr. When compared to spectroscopic observations done in 2009, the spectrum of V4332 Sgr considerably evolved between 2005 and 2009. The object significantly faded in the optical (by ~2mag in the V band), which resulted from the main remnant cooled by 300-350K corresponding to its spectral type changed from M3 to M5-6. The object however increased in luminosity by ~50%, implying a significant expansion of its dimensions. Most of the emission features seen in 2005 significantly faded or even disappeared from the spectrum of V4332 Sgr in 2009.
We report the first detection of pure rotational transitions of TiO and TiO2 at (sub-)millimeter wavelengths towards the red supergiant VYCMa. A rotational temperature, Trot, of about 250K was derived for TiO2. Although Trot was not well constrained for TiO, it is likely somewhat higher than that of TiO2. The detection of the Ti oxides confirms that they are formed in the circumstellar envelopes of cool oxygen-rich stars and may be the "seeds" of inorganic-dust formation, but alternative explanations for our observation of TiO and TiO2 in the cooler regions of the envelope cannot be ruled out at this time. The observations suggest that a significant fraction of the oxides is not converted to dust, but instead remains in the gas phase throughout the outflow.
One of the most promising avenues for the detailed study of temperate Earth-sized exoplanets is the detection of such planets in transit in front of stars that are small and near enough to make it possible to carry out a thorough atmospheric characterisation with next-generation telescopes, such as the James Webb Space telescope (JWST) or Extremely Large Telescope (ELT). In this context, the TRAPPIST-1 planets form a unique benchmark system that has garnered the interest of a large scientific community. The SPECULOOS survey is an exoplanet transit survey targeting a volume-limited (40pc) sample of ultracool dwarf stars (of spectral type M7 and later) that is based on a network of robotic 1m telescopes especially designed for this survey. The strategy for brighter and earlier targets leverages its synergy with the ongoing TESS space-based exoplanet transit survey. We define the SPECULOOS target list as the sum of three non-overlapping sub-programmes incorporating the latest type objects (Teff<3000K). Programme1 features 365 dwarfs that are small and near enough to make it possible to detail atmospheric characterisation of an 'Earth-like' planet with the upcoming James Webb Space Telescope (JWST). Programme2 features 171 dwarfs of M5-type and later for which a significant detection of a planet similar to TRAPPIST-1b should be within reach of TESS. Programme3 features 1121 dwarfs that are later than M6-type. These programmes form the basis of our statistical census of short-period planets around ultracool dwarf stars. Our compound target list includes 1657 photometrically classified late-type dwarfs, with 260 of these targets classified, for the first time, as possible nearby ultracool dwarf stars. Our general observational strategy was to monitor each target between 100 and 200hr with our telescope network, making efficient use of the synergy with TESS for our Programme2 targets and a proportion of targets in our Programme1. Based on Monte Carlo simulations, we expect to detect up to a few dozen temperate, rocky planets. We also expect a number of them to prove amenable for atmospheric characterisation with JWST and other future giant telescopes, which will substantially improve our understanding of the planetary population of the latest-type stars.
We report the discovery of the L dwarf WISE J174102.78-464225.5, which was discovered as part of a search for nearby L dwarfs using the Wide-field Infrared Survey Explorer (WISE). The distinct triangular peak of the H-band portion of its near-infrared spectrum and its red near-infrared colors (J-K_S_=2.35+/-0.08mag) are indicative of a young age. Via comparison to spectral standards and other red L dwarfs, we estimate a near-infrared spectral type of L7+/-2 (pec). From a comparison to spectral and low-mass evolutionary models, we determine self-consistent effective temperature, logg, age, and mass values of 1450+/-100K, 4.0+/-0.25 (cm/s2), 10-100Myr, and 4-21M_Jup_, respectively. With an estimated distance of 10-30pc, we explore the possibility that WISE J174102.78-464225.5 belongs to one of the young nearby moving groups via a kinematic analysis and we find potential membership in the {beta} Pictoris or AB Doradus associations. A trigonometric parallax measurement and a precise radial velocity can help to secure its membership in either of these groups.
We present a catalog of near-infrared (NIR) spectra and associated measurements for 886 nearby M dwarfs. The spectra were obtained with the NASA-Infrared Telescope Facility SpeX Spectrograph during a two-year observing campaign; they have high signal-to-noise ratios (S/N>100-150), span 0.8-2.4{mu}m, and have R~2000. Our catalog of measured values contains useful T_eff_ and composition-sensitive features, empirical stellar parameter measurements, and kinematic, photometric, and astrometric properties compiled from the literature. We focus on measurements of M dwarf abundances ([Fe/H] and [M/H]), capitalizing on the precision of recently published empirical NIR spectroscopic calibrations. We explore systematic differences between different abundance calibrations, and from other similar M dwarf catalogs. We confirm that the M dwarf abundances we measure show the expected inverse dependence with kinematic-, activity-, and color-based age indicators. Finally, we provide updated [Fe/H] and [M/H] for 16 M dwarf planet hosts. This catalog represents the largest published compilation of NIR spectra and associated parameters for M dwarfs. It provides a rich and uniform resource for nearby M dwarfs, and will be especially valuable for measuring Habitable Zone locations and comparative abundances of the M dwarf planet hosts that will be uncovered by upcoming exoplanet surveys.
We report the identification of 17 candidate brown dwarf binaries whose components straddle the L dwarf/T dwarf transition. These sources were culled from a large near-infrared spectral sample of L and T dwarfs observed with the Infrared Telescope Facility SpeX spectrograph. Candidates were selected on the basis of spectral ratios which segregate known (resolved) L dwarf/T dwarf pairs from presumably single sources. Composite templates, constructed by combining 13581 pairs of absolute flux-calibrated spectra, are shown to provide statistically superior fits to the spectra of our 17 candidates as compared to single templates. Ten of these candidates appear to have secondary components that are significantly brighter than their primaries over the 1.0-1.3um band, indicative of rapid condensate depletion at the L dwarf/T dwarf transition. Our results support prior indications of enhanced multiplicity amongst early-type T dwarfs; 53+/-7% of the T0-T4 dwarfs in our spectral sample are found to be either resolved or unresolved (candidate) pairs, although this is consistent with an intrinsic (volume complete) brown dwarf binary fraction of only 15%. If verified, this sample of spectral binaries more than doubles the number of known L dwarf/T dwarf transition pairs, enabling a broader exploration of this poorly understood phase of brown dwarf atmospheric evolution.