Search Publications
Ion conics and electron beams associated with auroral processes on Saturn
Krupp, N.; Dougherty, M. K.; Hospodarsky, G. B. +7 more
Ion conics accompanied by electron beams are observed regularly in Saturn's magnetosphere. The beams and conics are seen throughout the outer magnetosphere, on field lines that nominally map from well into the polar cap (Ldipole > 50) to well into the closed field region (Ldipole < 10). The electron beams and ion conics…
Plasma boundary variability at Mars as observed by Mars Global Surveyor and Mars Express
Barabash, S.; Fränz, M.; Lester, M. +4 more
We have used Mars Express (MEX) and Mars Global Surveyor (MGS) simultaneous and non-simultaneous measurements to study the Martian plasma environment. In particular, we have derived quantitative expressions for the altitude of the terminator bow shock (BS) and magnetic pileup boundary (MPB) as functions of solar wind dynamic pressure, crustal magn…
The ACS LCID Project. I. Short-Period Variables in the Isolated Dwarf Spheroidal Galaxies Cetus and Tucana
Skillman, Evan D.; Cole, Andrew A.; Tolstoy, Eline +9 more
We present the first study of the variable star populations in the isolated dwarf spheroidal galaxies (dSphs) Cetus and Tucana. Based on Hubble Space Telescope images obtained with the Advanced Camera for Surveys in the F475W and F814W bands, we identified 180 and 371 variables in Cetus and Tucana, respectively. The vast majority are RR Lyrae star…
The zCOSMOS survey: the role of the environment in the evolution of the luminosity function of different galaxy types
Kneib, J. -P.; Maccagni, D.; Aussel, H. +64 more
Aims. An unbiased and detailed characterization of the galaxy luminosity function (LF) is a basic requirement in many astrophysical issues: it is of particular interest in assessing the role of the environment in the evolution of the LF of different galaxy types.
Methods: We studied the evolution in the B band LF to redshift z∼ 1 in the zCOSM…
Empirical estimate of Lyα escape fraction in a statistical sample of Lyα emitters
Schaerer, D.; Östlin, G.; Hayes, M. +4 more
Context: The Lyman-alpha (Lyα) recombination line is a fundamental tool for galaxy evolution studies and modern observational cosmology. However, subsequent interpretations are still prone to a number of uncertainties. Besides numerical efforts, empirical data are urgently needed for a better understanding of the Lyα escape process.
Aims: We e…
The XMM -Newton view of AGN with intermediate-mass black holes
Ponti, G.; Iwasawa, K.; Fabian, A. C. +3 more
We have observed with XMM-Newton four radiatively efficient active type 1 galaxies with black hole masses <106Msolar, selected optically from the Sloan Digital Sky Survey and previously detected in the ROSAT All Sky Survey. Their X-ray spectra closely resemble those of more luminous Seyferts and quasars, powered by accreti…
A cool starspot or a second transiting planet in the TrES-1 system?
Alonso, R.; Deeg, H. J.; Brown, T. M. +6 more
Aims: We investigate the origin of a flux increase found during a transit of TrES-1, observed with the HST (Hubble Space Telescope). This feature in the HST light curve cannot be attributed to noise and is supposedly a dark area on the stellar surface of the host star eclipsed by TrES-1 during its transit. We investigate the likelihood of two poss…
Quantitative Examination of Supra-arcade Downflows in Eruptive Solar Flares
Savage, Sabrina L.; McKenzie, D. E.
Downward motions above post-coronal mass ejection flare arcades are an unanticipated discovery of the Yohkoh mission, and have subsequently been detected with TRACE, SOHO/LASCO, SOHO/SUMER, and Hinode/XRT. These supra-arcade downflows are interpreted as outflows from magnetic reconnection, consistent with a three-dimensional generalization of the …
Global circulation as the main source of cloud activity on Titan
Sotin, Christophe; Barnes, Jason W.; Le Mouélic, Stéphane +11 more
Clouds on Titan result from the condensation of methane and ethane and, as on other planets, are primarily structured by circulation of the atmosphere. At present, cloud activity mainly occurs in the southern (summer) hemisphere, arising near the pole and at mid-latitudes from cumulus updrafts triggered by surface heating and/or local methane sour…
The Evolution of Early- and Late-type Galaxies in the Cosmic Evolution Survey up to z ≈ 1.2
Bender, Ralf; Drory, Niv; Pannella, Maurilio +6 more
The Cosmic Evolution Survey (COSMOS) allows for the first time a highly significant census of environments and structures up to redshift 1, as well as a full morphological description of the galaxy population. In this paper we present a study aimed to constrain the evolution, in the redshift range 0.2 < z < 1.2, of the mass content of differ…