Search Publications
Short Gas Dissipation Timescales: Diskless Stars in Taurus and Chamaeleon I
Briceño, Cesar; Calvet, Nuria; Herczeg, Gregory +1 more
We present an Advanced Camera for Surveys/Solar Blind Channel far-ultraviolet (FUV) study of H2 gas in 12 weak T Tauri stars in nearby star-forming regions. The sample consists of sources which have no evidence of inner disk dust. Our new FUV spectra show that in addition to the dust, the gas is depleted from the inner disk. This sample…
Counterrotation in Magnetocentrifugally Driven Jets and Other Winds
Tsinganos, K.; Cayatte, V.; Lima, J. J. G. +2 more
Rotation measurement in jets from T Tauri stars is a rather difficult task. Some jets seem to be rotating in a direction opposite to that of the underlying disk, although it is not yet clear if this affects the totality or part of the outflows. On the other hand, Ulysses data also suggest that the solar wind may rotate in two opposite ways between…
On the Distribution of Quiet-Sun Magnetic Fields at Different Heliocentric Angles
Katsukawa, Y.; Orozco Suárez, D.
This paper presents results from the analysis of high signal-to-noise ratio spectropolarimetric data taken at four heliocentric angles in quiet-Sun internetwork regions with the Hinode satellite. First, we find that the total circular and total linear polarization signals vary with heliocentric angle, at least for fields with large polarization si…
Cluster 77 in NGC 4449: The Nucleus of a Satellite Galaxy Being Transformed into a Globular Cluster?
Tosi, M.; van der Marel, R. P.; Aloisi, A. +2 more
We report the discovery in our Hubble Space Telescope Advanced Camera for Surveys B, V, and I images of NGC 4449 of a globular cluster (GC) which appears associated with two tails of blue stars. The cluster is massive (M ~ 1.7 × 106 M ⊙) and highly flattened (epsilon ~ 0.24). From the color-magnitude diagrams of the resolved …
Bubbles and Knots in the Kinematical Structure of the Bipolar Planetary Nebula NGC 2818
Vázquez, Roberto
High-resolution Hubble Space Telescope archive imaging and high-dispersion spectroscopy are used to study the complex morphological and kinematical structure of the planetary nebula, NGC 2818. We analyze narrowband Hα, [O III], [N II], [S II], and He II images, addressing important morphological features. Ground-based long-slit echelle spectra wer…
On the Polarimetric Signature of Emerging Magnetic Loops in the Quiet Sun
Viticchié, B.
The abundance of Stokes V profiles dominated by one lobe at the locations of emergence of Ω-shaped magnetic loops is evaluated. The emergence events were found in Hinode Solar Optical Telescope/spectro-polarimeter time sequences of quiet-Sun regions. Such a study has the aim of confirming a prediction based on the basic geometrical and physical pr…
Searching for γ-Ray Blazar Candidates among the Unidentified INTEGRAL Sources
Tosti, G.; Massaro, F.; Paggi, A. +1 more
The identification of low-energy counterparts for γ-ray sources is one of the biggest challenges in modern γ-ray astronomy. Recently, we developed and successfully applied a new association method to recognize γ-ray blazar candidates that could be possible counterparts for the unidentified γ-ray sources above 100 MeV in the second Fermi Large Area…
The Herschel Filament: A Signature of the Environmental Drivers of Galaxy Evolution during the Assembly of Massive Clusters at z = 0.9
Egami, E.; Yee, H. K. C.; Gladders, M. +11 more
We have discovered a 2.5 Mpc (projected) long filament of infrared-bright galaxies connecting two of the three ~5 × 1014 M ⊙ clusters making up the RCS 2319+00 supercluster at z = 0.9. The filament is revealed in a deep Herschel Spectral and Photometric Imaging REceiver (SPIRE) map that shows 250-500 µm emission associa…
Measuring the Geometry of the Universe from Weak Gravitational Lensing behind Galaxy Groups in the HST COSMOS Survey
Koekemoer, Anton M.; Ellis, Richard; Leauthaud, Alexie +12 more
Gravitational lensing can provide pure geometric tests of the structure of spacetime, for instance by determining empirically the angular diameter distance-redshift relation. This geometric test has been demonstrated several times using massive clusters which produce a large lensing signal. In this case, matter at a single redshift dominates the l…
XMM-Newton Observation of the Very Old Pulsar J0108-1431
Manchester, R. N.; Pavlov, G. G.; Shannon, R. M. +3 more
We report on an X-ray observation of the 166 Myr old radio pulsar J0108-1431 with XMM-Newton. The X-ray spectrum can be described by a power-law model with a relatively steep photon index Γ ≈ 3 or by a combination of thermal and non-thermal components, e.g., a power-law component with fixed photon index Γ = 2 plus a blackbody component with a temp…