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Investigating target versus impactor influences on Martian crater morphology at the simple-complex transition
Hynek, Brian M.; Herrick, Robert R.
Comparing craters of identical diameter on a planet is an empirical method of studying the effects of different target and impactor properties while holding total impact energy nearly constant. We have analyzed the Martian crater population within a narrow diameter range (7 km < crater diameter < 9 km) at the simple-complex crater transition…
Machine learning techniques to select Be star candidates. An application in the OGLE-IV Gaia south ecliptic pole field
Hernández, J.; Pérez-Ortiz, M. F.; García-Varela, A. +2 more
Context. Optical and infrared variability surveys produce a large number of high quality light curves. Statistical pattern recognition methods have provided competitive solutions for variable star classification at a relatively low computational cost. In order to perform supervised classification, a set of features is proposed and used to train an…
Toward Understanding The B[e] Phenomenon. VI. Nature and Spectral Variations of HD 85567.
Reichart, D. E.; Miroshnichenko, A. S.; Haislip, J. B. +7 more
We report the results of high-resolution (R ∼ 80,000) spectroscopic observations of the emission-line object HD 85567, which has been classified as an FS CMa type object or a pre-main-sequence star. The main goal is to put more constraints on the object’s fundamental parameters, as well as on its nature and evolutionary state. Absorption lines in …
Testing physical models for dipolar asymmetry with CMB polarization
Banday, A. J.; Górski, K. M.; Scott, D. +2 more
The cosmic microwave background (CMB) temperature anisotropies exhibit a large-scale dipolar power asymmetry. To determine whether this is due to a real, physical modulation or is simply a large statistical fluctuation requires the measurement of new modes. Here we forecast how well CMB polarization data from Planck and future experiments will be …
Millimeter observations of the disk around GW Orionis
Fedele, D.; Wang, Y.; Wang, J. Z. +4 more
The GW Ori system is a pre-main sequence triple system (GW Ori A/B/C) with companions (GW Ori B/C) at 1 AU and 8 AU, respectively, from the primary (GW Ori A). The primary of the system has a mass of 3.9 M⊙, but shows a spectral type of G8. Thus, GW Ori A could be a precursor of a B star, but it is still at an earlier evolutionary stage…
Gas inflows towards the nucleus of NGC 1358
Robinson, Andrew; Schnorr-Müller, Allan; Storchi-Bergmann, Thaisa +2 more
We use optical spectra from the inner 1.8 × 2.5 kpc2 of the Seyfert 2 galaxy NGC 1358, obtained with the GMOS integral field spectrograph on the Gemini South telescope at a spatial resolution of ≈ 165 pc, to assess the feeding and feedback processes in this nearby active galaxy. Five gaseous kinematical components are observed in the em…
A Closer Look at the Alpha Persei Coronal Conundrum
Ayres, Thomas R.
A ROSAT survey of the Alpha Per open cluster in 1993 detected its brightest star, the mid-F supergiant α Persei: the X-ray luminosity and spectral hardness were similar to coronally active late-type dwarf members. Later, in 2010, a Hubble Cosmic Origins Spectrograph SNAPshot of α Per found the far-ultraviolet (FUV) coronal-proxy Si IV unexpectedly…
Herschel GASPS spectral observations of T Tauri stars in Taurus. Unraveling far-infrared line emission from jets and discs
Dent, W. R. F.; Kamp, I.; Eiroa, C. +5 more
Context. At early stages of stellar evolution young stars show powerful jets and/or outflows that interact with protoplanetary discs and their surroundings. Despite the scarce knowledge about the interaction of jets and/or outflows with discs, spectroscopic studies based on Herschel and ISO data suggests that gas shocked by jets and/or outflows ca…
Automatic detection of Martian dark slope streaks by machine learning using HiRISE images
Di, Kaichang; Wang, Yexin; Xin, Xin +1 more
Dark slope streaks (DSSs) on the Martian surface are one of the active geologic features that can be observed on Mars nowadays. The detection of DSS is a prerequisite for studying its appearance, morphology, and distribution to reveal its underlying geological mechanisms. In addition, increasingly massive amounts of Mars high resolution data are n…
Post-perihelion observations of comet 67P/Churyumov-Gerasimenko at the 6 m BTA telescope: optical spectroscopy
Afanasiev, V. L.; Kiselev, N. N.; Ivanova, O. V. +2 more
In the framework of the worldwide ground-based campaign, long-slit spectroscopy of comet 67P/Churyumov-Gerasimenko was performed at the 6 m BTA telescope of the Special Astrophysical Observatory RAS in the post-perihelion period from 2015 November to 2016 April at a heliocentric distance from 1.61 to 2.72 au. Strong CN and relatively weak C2<…