J. E. Steiner

Gas streaming motions towards the nucleus of M81

We present two-dimensional stellar and gaseous kinematics of the inner 120xa0×xa0250xa0pc2 of the LINER/Seyfertxa01 galaxy M81, from optical spectra obtained with the Gemini Multi-Object Spectrograph (GMOS) integral field spectrograph on the Gemini-North telescope at a spatial resolution of ≈10xa0pc. The stellar velocity field shows circular rotation and, overall, is very similar to the published large-scale velocity field, but deviations are observed close to the minor axis which can be attributed to stellar motions possibly associated with a nuclear bar. The stellar velocity dispersion of the bulge is 162xa0±xa015xa0kmxa0s−1, in good agreement with previous measurements and leading to a black hole mass of MBH=xa05.5+3.6−2.0× 107xa0M⊙ based on the MBH–σ relationship. The gas kinematics is dominated by non-circular motions and the subtraction of the stellar velocity field reveals blueshifts of ≈−100xa0kmxa0s−1 on the far side of the galaxy and a few redshifts on the near side. These characteristics can be interpreted in terms of streaming towards the centre if the gas is in the plane. On the basis of the observed velocities and geometry of the flow, we estimate a mass inflow rate in ionized gas of ≈4.0xa0×xa010−3xa0M⊙xa0yr−1, which is of the order of the accretion rate necessary to power the LINER nucleus of M81. We have also applied the technique of principal component analysis (PCA) to our data, which reveals the presence of a rotating nuclear gas disc within ≈50xa0pc from the nucleus and a compact outflow, approximately perpendicular to the disc. The PCA combined with the observed gas velocity field shows that the nuclear disc is being fed by gas circulating in the galaxy plane. The presence of the outflow is supported by a compact jet seen in radio observations at a similar orientation, as well as by an enhancement of the [Oxa0i]/Hα line ratio, probably resulting from shock excitation of the circumnuclear gas by the radio jet. With these observations we are thus resolving both the feeding – via the nuclear disc and observed gas inflow, and the feedback – via the outflow, around the low-luminosity active nucleus of M81.

Cyclical period changes in the dwarf novae V2051 Oph and V4140 Sgr

We report the identification of cyclical changes in the orbital period of the eclipsing dwarf novae V2051 Ophiuchi and V4140 Sagitarii. We used sets of white dwarf mideclipse timings to construct observed-minus-calculated diagrams covering, respectively, 25 and 16 years of observations. The V2051 Oph data present cyclical variations that can be fitted by a linear plus sinusoidal function with period 22±2 yr and amplitude 17±3 s. The statistical significance of this period by an F-test is larger than 99.9 per cent. The V4140 Sgr data present cyclical variations of similar amplitude and period 6.9 ± 0.3 yr which are statistically significant at the 99.7 per cent level. We derive upper limits for secular period changes of | u P| < 3 × 10 12 and | u P| < 1.8 × 10 11 , respectively for V2051 Oph and V4140 Sgr. We combined our results with those in the literature to construct a diagram of the amplitude versus period of the modulation for a sample of 11 eclipsing cataclysmic variables (CVs). If the cyclical period changes are the consequence of a solar-type magnetic activity cycle in the secondary star, then magnetic activity is a widespread phenomenon in CVs, being equally common among long- and short-period systems. This gives independent evidence that the magnetic field (and activity) of the secondary stars of CVs do not disappear when they become fully convective. We also find that the fractional cycle period changes of the short-period CVs are systematically smaller than those of the long-period CVs.

WX Cen (≡ WR 48c) – a possible Type Ia supernova progenitor

We confirm the orbital period of WX Cen ≡ WR 48c determined by Diaz & Steiner and refined its value to P orb = 0.416 961 5(±22) d. The light curve of this object has a peak-to-peak variation of approximately 0.32 mag. It is non-sinusoidal in the sense that it has a V-shaped narrow minimum, similar to the ones seen in V Sge, V617 Sgr and in compact binary supersoft sources (CBSS). Most of the emission lines in the optical spectrum are due to Balmer, He II, C IV, N v, O v and O vi. An analysis of the He II Pickering series decrement shows that the system has significant amount of hydrogen. The emission lines of He II 4686 A became weaker between the 1991 and 2000/2002 observations, indicating distinct levels of activity. The spectra of WX Cen show variable absorption features in the Balmer lines with V = -2900 km s -1 and in emission with V = ±3500 km s -1 . These highly variable features remind us of the satellite emission lines found in the spectra of CBSS. We estimate the colour excess as E(B - V) = 0.63 on the basis of the observed diffuse interstellar band at 5780 A. Given the distance-colour excess relation in the direction of WX Cen, this implies a distance of 2.8 ± 0.3 kpc. Interstellar absorption of the Na I D lines show components at -4.1 km s -1 , which corresponds to the velocity of the Coalsack, and three other components at -23.9, -32.0 and -39.0 km s -1 . These components are also seen with similar strengths in field stars that have distances between 1.8 and 2.7 kpc. The intrinsic colour of WX Cen is (B - V) 0 = -0.2 and the absolute magnitude is M V = -0.5. Extended red wings in the strong emission lines are seen. A possible explanation is that the system has a spill-over stream similar to what is seen in V617 Sgr. We predict that when observed in opposite phase, blue wings would be observed. A puzzling feature that remains to be explained is the highly variable red wing (V ∼ 700 km s -1 ) of the O VI emission lines as well as of the red wings of the H and He lines. The velocity of the satellite-like feature is consistent with the idea that the central star is a white dwarf with a mass of M ∼ 0.9 M ○. . With the high accretion rate under consideration, the star may become a Type Ia supernova (SN Ia) in a time-scale of 5 x 10 6 yr.

WR 7a: a V Sagittae or a qWR star?

The star WR 7a, also known as SPH 2, has a spectrum that resembles that of V Sagittae stars although no Oxa0vi emission has been reported. The Temporal Variance Spectrum – TVS – analysis of our data shows weak but strongly variable emission of Oxa0vi lines which is below the noise level in the intensity spectrum. n n n nContrary to what is seen in V Sagittae stars, optical photometric monitoring shows very little, if any, flickering. We found evidence of periodic variability. The most likely photometric period is Pphot= 0.227(±14) d, while radial velocities suggest a period of Pspec= 0.204(±13) d. One-day aliases of these periods can not be ruled out. We call attention to similarities with HD 45166 and DI Cru (= WR 46), where multiple periods are present. They may be associated to the binary motion or to non-radial oscillations. n n n nIn contrast to a previous conclusion by Pereira et al., we show that WR 7a contains hydrogen. The spectrum of the primary star seems to be detectable as the Nxa0v 4604xa0Axa0xa0absorption line is visible. If so, it means that the wind is optically thin in the continuum and that it is likely to be a helium main sequence star. n n n nGiven the similarity to HD 45166, we suggests that WR 7a may be a qWR – quasi Wolf–Rayet – star. Its classification is WN4h/CE in the Smith, Shara & Moffat three-dimensional classification system.

The Multiple Spectroscopic and Photometric Periods of DI Crucis (WR 46)

In an effort to determine the orbital period of the enigmatic star DI Cru (HD 104994, WR 46), we made photometric and spectroscopic observations of this object between 1996 and 2002. Both photometric and spectroscopic characteristics are quite complex. The star is highly variable on short (few hour) as well as on long (few month) timescales. The optical spectrum is rich in strong emission lines of high-ionization species such as He ii ,N iv ,N v, and O vi. Weak emission of C iii is also present. Emission lines have been compiled and identified from the ultraviolet to the infrared. In the UV, emission of O v and N iv is also observed, together with very weak emission of C iv. The N v ll4603, 4619/He ii l4686 line ratios vary by a significant amount from night to night. Temporal variance spectrum analysis shows that the He ii l4686 line has P Cyg-like variable absorption, while N v ll4603, 4619 lines have a strong and broad variable component due to the continuum fluorescence from a source (stellar atmosphere/optically thick wind) of variable temperature. We also show that the object has variable degree of ionization, probably caused by wind density variation. The star presents multiple periods in radial velocity and photometry. From our data we derived a main radial velocity period of 0.3319 days with an amplitude of km s 1 . This period is similar to the value found by Marchenko and coworkers. K p 58 When at intermediate brightness, this period is also seen in the photometric measurements. When the star is at bright phase, the photometric variations do not present the same period. Photometric periods ranging from 0.154 to 0.378 days are present, consistent with observations reported by other authors. Besides the 0.3319 day period, other spectroscopic periods are also seen. On distinct epochs, the periods are different; Marchenko et al. interpreted the 0.3319 day period as the orbital one. Although we do not discard this possibility, the true binary nature (e.g., long-term coherence or detection of a secondary star) has not yet been demonstrated. DI Cru is a Population I WR object. Given the similarities (e.g., multiple periods likely due to nonradial oscillations), it could be interpreted as a luminous counterpart of the qWR star HD 45166.

A origem do universo

THE VARIOUS cosmological models along history are briefly reviewed. The evolution of the ideas may be understood as successive models such as the flat earth, the geocentric models as well as the heliocentric and the galacto-centric ones. In the last century, a concept was developed, the big-bang theory, that describes the most sophisticated observations on hand today and shows that the universe had an origin that can be search with scientific methods. In recent decades this model was refined to a new concept: inflation. By the end of the century and millenium new discoveries showed that all known matter is only the tip of the iceberg in a universe dominated by dark energy and dark matter whose natures remain mysterious.HE ORIGIN OF THINGS has always been a central concern for humanity; the origin of the stones, the animals, the plants, the planets, the stars and we ourselves. Yet the most fundamental origin of them all would seem to be the origin of the universe as a whole – of everything that exists, without which there could be none of the creatures and things mentioned above, including ourselves. Perhaps that is why the existence of the universe, its origin and nature, has been a subject of explanation in almost all civilizations and cultures. In fact, every culture known to anthropology has had a cosmogony – a history of how the world began and continues, of how mankind was created and of what the gods expect of us. The understanding these civilizations had of the universe is very different to what science teaches us today. However, the absence of a cosmology in

THE MOLECULAR H2 EMISSION AND THE STELLAR KINEMATICS IN THE NUCLEAR REGION OF THE SOMBRERO GALAXY

We analyze the molecular H2 emission and the stellar kinematics in a data cube of the nuclear region of M104, the Sombrero galaxy, obtained with NIFS on the Gemini-north telescope. After a careful subtraction of the stellar continuum, the only emission line we detected in the data cube was . An analysis of this emission revealed the existence of a rotating molecular torus/disk, aproximately co-planar with a dusty structure detected by us in a previous work. We interpret these two structures as being associated with the same obscuring torus/disk. The kinematic maps provided by the Penalized Pixel Fitting method revealed that the stellar kinematics in the nuclear region of M104 appears to be the result of the superposition of a “cold” rotating disk and a “hot” bulge. Using a model of a thin eccentric disk, we reproduced the main properties of the maps of the stellar radial velocity and of the stellar velocity dispersion, especially within a distance of from the kinematic axis (in regions at larger distances, the limitations of a model of a thin rotating disk become more visible). The general behavior of the h3 map, which is significantly noisier than the other maps, was also reproduced by our model (although the discrepancies, in this case, are considerably higher). With our model, we obtained a mass of for the supermassive black hole of M104, which is compatible, at or levels, with the values obtained by previous studies.

V529 Coronae Austrinae: An RV Tauri Variable of Type RVb1

We present an analysis of the photometric data on V529 CrA. The data include published photographic data as well as our own UBV(RI)C measurements. Two dominant modulations with periods of 23.571 and 761.5 days are present in the light curve. The double of the 23.571 day period (47.142 days) shows the alternating deep/shallow minima behavior of the RV Tauri class of variables, while the presence of a longer modulation indicates a classification in the photometric subclass RVb. Medium-resolution optical spectroscopy is also presented.

The GMT-consortium large earth finder (G-CLEF): an optical echelle spectrograph for the Giant Magellan Telescope (GMT)

The GMT-Consortium Large Earth Finder (G-CLEF) is an instrument that is being designed to exceed the state-of-the-art radial velocity (RV) precision achievable with the current generation of stellar velocimeters. It is simultaneously being designed to enable a wide range of scientific programs, prominently by operating to blue wavelengths (< 3500Å). G-CLEF will be the first light facility instrument on the Giant Magellan Telescope (GMT) when the GMT is commissioned in 2023. G-CLEF is a fiber-fed, vacuum-enclosed spectrograph with an asymmetric white pupil echelle design. We discuss several innovative structural, optical and control system features that differentiate G-CLEF from previous precision RV instruments.

Integral field spectroscopy of the inner kpc of the elliptical galaxy NGC 5044

We used Gemini Multi-Object Spectrograph (GMOS) in the Integral Field Unit mode to map the stellar population, emission line flux distributions and gas kinematics in the inner kpc of NGC 5044. From the stellar populations synthesis we found that the continuum emission is dominated by old high metallicity stars (