Search Publications
Environmental effects on AGN activity via extinction-free mid-infrared census
Hashimoto, Tetsuya; Goto, Tomotsugu; Kim, Seong Jin +20 more
How does the environment affect active galactic nucleus (AGN) activity? We investigated this question in an extinction-free way by selecting 1120 infrared (IR) galaxies in the AKARI North Ecliptic Pole Wide field at redshift z ≤ 1.2. A unique feature of the AKARI satellite is its continuous nine-band IR filter coverage, providing us with an unprec…
Molecular gas budget and characterization of intermediate-mass star-forming galaxies at z ≈ 2-3
Dahle, H.; Rigby, J. R.; Sharon, K. +9 more
Star-forming galaxies (SFGs) with stellar masses below 1010 M⊙ make up the bulk of the galaxy population at z > 2. The properties of the cold gas in these galaxies can only be probed in very deep observations or by targeting strongly lensed galaxies. Here we report the results of a pilot survey using the Atacama Compact Ar…
The temperatures of red supergiants in low-metallicity environments
Kudritzki, Rolf-Peter; Davies, Ben; González-Torà, Gemma +1 more
The temperatures of red supergiants (RSGs) are expected to depend on metallicity (Z) in such a way that lower Z RSGs are warmer. In this work, we investigate the Z-dependence of the Hayashi limit by analysing RSGs in the low-Z galaxy Wolf-Lundmark-Mellote, and compare with the RSGs in the higher Z environments of the Small Magellanic Cloud and Lar…
Chandra grating spectroscopy of embedded wind shock X-ray emission from O stars shows low plasma temperatures and significant wind absorption
Leutenegger, Maurice A.; Cohen, David H.; Gagné, Marc +4 more
We present a uniform analysis of six examples of embedded wind shock (EWS) O star X-ray sources observed at high resolution with the Chandra grating spectrometers. By modelling both the hot plasma emission and the continuum absorption of the soft X-rays by the cool, partially ionized bulk of the wind we derive the temperature distribution of the s…
HD 344787: a true Polaris analogue?
Plachy, E.; Clementini, G.; Ripepi, V. +10 more
Context. Classical Cepheids (DCEPs) are the most important primary indicators for the extragalactic distance scale, but they are also important objects in their own right, allowing us to place constraints on the physics of intermediate-mass stars and the pulsation theories.
Aims: We have investigated the peculiar DCEP HD 344787, which is know…
An investigation of open cluster Melotte 72 using Gaia DR2
Hendy, Yasser; Tadross, Ashraf
The estimation of the main parameters of star clusters is significant in astrophysical studies. The most important aspect of using the Gaia DR2 survey lies in the positions, parallax, and proper motions of cluster stars with homogeneous photometry that make the membership probability determine with high accuracy. In this respect, depending on Gaia…
Transmission of an ICME Sheath Into the Earth's Magnetosheath and the Occurrence of Traveling Foreshocks
Pulkkinen, Tuija I.; Dimmock, Andrew P.; Turc, Lucile +4 more
The transmission of a sheath region driven by an interplanetary coronal mass ejection into the Earth's magnetosheath is studied by investigating in situ magnetic field measurements upstream and downstream of the bow shock during an ICME sheath passage on 15 May 2005. We observe three distinct intervals in the immediate upstream region that include…
The Stellar Initial Mass Function and Population Properties of M89 from Optical and NIR Spectroscopy: Addressing Biases in Spectral Index Analysis
Freedman, Wendy L.; Feldmeier-Krause, A.; Lonoce, I.
The complexity of constraining the stellar initial mass function (IMF) in early-type galaxies cannot be overstated, given the necessity of very high signal-to-noise ratio (S/N) data and the difficulty of breaking the strong degeneracies that occur among several stellar population parameters, including age, metallicity, and elemental abundances. Wi…
NOEMA Redshift Measurements of Extremely Bright Submillimeter Galaxies near the GOODS-N
Cowie, Lennox L.; Barger, Amy J.; Jones, Logan H. +1 more
We report spectroscopic redshift measurements for three bright submillimeter galaxies (SMGs) near the GOODS-N field, each with SCUBA-2 850 µm fluxes >10 mJy, using the Northern Extended Millimeter Array (NOEMA). Our molecular line-scan observations of these sources, which occupy an ~7 arcmin2 area outside of the Hubble Space Te…
Orbits and Masses of Binaries from Speckle Interferometry at SOAR
Mendez, Rene A.; Clavería, Rubén M.; Costa, Edgardo
We present results from Speckle inteferometric observations of 15 visual binaries and one double-line spectroscopic binary, carried out with the HRCam Speckle camera of the SOAR 4.1 m telescope. These systems were observed as a part of an on-going survey to characterize the binary population in the solar vicinity, out to a distance of 250 pc. We o…