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Searching for Cool Dust in the Mid-to-far Infrared: The Mass-loss Histories of the Hypergiants µ Cep, VY CMa, IRC+10420, and ρ Cas

Gehrz, Robert D.; Humphreys, Roberta M.; Jones, Terry J. +6 more

We present mid- and far-IR imaging of four famous hypergiant stars: the red supergiants µ Cep and VY CMa, and the warm hypergiants IRC +10420 and ρ Cas. Our 11-37 µm SOFIA/FORCAST imaging probes cool dust not detected in visual and near-IR imaging studies. Adaptive optics 8-12 µm imaging of µ Cep and IRC +10420 with MMT/MIR…

A Distant Echo of Milky Way Central Activity Closes the Galaxy’s Baryon Census

Elvis, M.; Nicastro, F.; Krongold, Y. +2 more

We report on the presence of large amounts of million-degree gas in the Milky Way’s interstellar and circum-galactic medium. This gas (1) permeates both the Galactic plane and the halo, (2) extends to distances larger than 60-200 kpc from the center, and (3) its mass is sufficient to close the Galaxy’s baryon census. Moreover, we show that a vast,…

The Wind Nebula around Magnetar Swift J1834.9-0846

Lin, L.; Kouveliotou, C.; Baring, M. G. +12 more

We report on the analysis of two deep XMM-Newton observations of the magnetar Swift J1834.9-0846 and its surrounding extended emission taken in 2014 March and October, 2.5 and 3.1 yr after the source went into outburst. The magnetar is only weakly detected in the first observation, with an absorption-corrected flux {F}_0.5-10{keV}≈ 4× {1…

Annual variations in the Martian bow shock location as observed by the Mars Express mission

Holmström, M.; Fränz, M.; Lester, M. +12 more

The Martian bow shock distance has previously been shown to be anticorrelated with solar wind dynamic pressure but correlated with solar extreme ultraviolet (EUV) irradiance. Since both of these solar parameters reduce with the square of the distance from the Sun, and Mars' orbit about the Sun increases by ∼0.3 AU from perihelion to aphelion, it i…

Large Magellanic Cloud Near-infrared Synoptic Survey. II. The Wesenheit Relations and Their Application to the Distance Scale

Wagner-Kaiser, R.; Sarajedini, Ata; Macri, Lucas M. +4 more

We present new near-infrared (NIR) Cepheid period-Wesenheit (P-W) relations in the LMC using time-series observations from the Large Magellanic Cloud NIR Synoptic Survey. We also derive optical+NIR P-W relations using V and I magnitudes from the Optical Gravitational Lensing Experiment. We employ our new JHK_s data to determine an indepe…

A young cluster with an extended main-sequence turnoff: confirmation of a prediction of the stellar rotation scenario

Salaris, M.; Larsen, S.; Cabrera-Ziri, I. +13 more

We present Hubble Space Telescope photometry of NGC 1850, a ∼100 Myr, ∼10⁵ M_⊙ cluster in the Large Magellanic Cloud. The colour-magnitude diagram clearly shows the presence of an extended main-sequence turnoff (eMSTO). The use of non-rotating stellar isochrones leads to an age spread of ∼40 Myr. This is in good agreement with…

Helical Kink Instability in a Confined Solar Eruption

Kliem, Bernhard; Hassanin, Alshaimaa

A model for strongly writhing confined solar eruptions suggests an origin in the helical kink instability of a coronal flux rope that remains stable against the torus instability. This model is tested against the well observed filament eruption on 2002 May 27 in a parametric MHD simulation study that comprises all phases of the event. Good agreeme…

Discovery of alunite in Cross crater, Terra Sirenum, Mars: Evidence for acidic, sulfurous waters

Murchie, Scott L.; Ehlmann, Bethany L.; Mustard, John F. +11 more

Matching dust emission structures and magnetic field in high-latitude cloud L1642: comparing Herschel and Planck maps

Juvela, M.; Montier, L.; Ristorcelli, I. +7 more

The nearby cloud L1642 is one of only two known very high latitude (|b| > 30 deg) clouds actively forming stars. It is a rare example of star formation in isolated conditions, and can reveal important details of star formation in general, e.g. of the effect of magnetic fields. We compare Herschel dust emission structures and magnetic field orie…

The F-GAMMA programme: multi-frequency study of active galactic nuclei in the Fermi era. Programme description and the first 2.5 years of monitoring

Pearson, T. J.; Nestoras, I.; Zensus, J. A. +15 more

Context. To fully exploit the scientific potential of the Fermi mission for the physics of active galactic nuclei (AGN), we initiated the F-GAMMA programme. Between 2007 and 2015 the F-GAMMA was the prime provider of complementary multi-frequency monitoring in the radio regime.
Aims: We quantify the radio variability of γ-ray blazars. We inve…