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The connection between space weather and Single Event Upsets in polar low earth orbit satellites
Katz, Sari; Goldvais, Uriel; Price, Colin
Space weather is driven and modulated by the activity in the Sun. Space weather events have the potential to inflict critical damage to space systems. Nowadays, space assets are essential in our basic needs, such as communications, cell phone networks, navigation systems, television and internet. Hence, understanding space weather dynamics and its…
A photospheric and chromospheric activity analysis of the quiescent retrograde-planet host ν Octantis A
Cantalloube, F.; Reffert, S.; Robertson, P. +4 more
The single-lined spectroscopic binary ν Octantis provided evidence of the first conjectured circumstellar planet demanding an orbit retrograde to the stellar orbits. The planet-like behaviour is now based on 1437 radial velocities (RVs) acquired from 2001 to 2013. ν Oct's semimajor axis is only 2.6 au with the candidate planet orbiting $\nu ~{\rm …
The First Photometric Investigation and Spectroscopic Analysis of Two Contact Binaries: ASAS J124343+1531.7 and LINEAR 2323566
Li, Kai; Michel, Raul; Xia, Qiqi +1 more
The multi-color passband CCD light curves of ASAS J124343+1531.7 and LINEAR 2323566 were first obtained by the 0.84 m Ritchey-Chrétien telescope with follow up observations by the WIYN 0.90 m Cassegrain telescope. The data from the Transiting Exoplanet Survey Satellite of ASAS J124343+1531.7 was also applied for subsequent analysis. By analyzing t…
Characterization of HD 206893 B from Near- to Thermal-infrared
Lee, Eve J.; Gao, Peter; Beichman, Charles +9 more
HD 206893 B is a brown-dwarf companion orbiting inside the debris disk of its host star. We detect the brown dwarf in the Ms band using the Keck/NIRC2 instrument and vortex coronagraph. We measure its magnitude to be ${Ms}={12.97}_{-0.11}^{0.10}$ . It is at an angular separation of 0"22 ± 0"03, and a position angle of 39.6° ± 5.4° east of north. U…
Collisional effects in the blue wing of Lyman-α
Kielkopf, J. F.; Allard, N. F.; Spiegelman, F.
Spectral observations below Lyman-α are now obtained with the Cosmic Origin Spectrograph (COS) on the Hubble Space Telescope. It is therefore necessary to provide an accurate treatment of the blue wing of the Lyman-α line that enables correct calculations of radiative transport in DA and DBA white dwarf stars. On the theoretical front, we very rec…
Ion Convection as a Function of Distance to the Neutral Sheet in Earth's Magnetotail
Hamrin, M.; Pitkänen, T.; Chong, Ghai Siung +1 more
We utilized 33 years of data obtained by the Geotail, THEMIS, Cluster and MMS missions to investigate the slow (<200 km/s) ion flows perpendicular to the magnetic field in Earth's magnetotail plasma sheet. By using plasma β as a proxy of distance to the neutral sheet, we find that the ion flow patterns vary systematically within the plasma shee…
What causes the absence of pulsations in Central Compact Objects in supernova remnants?
Xiao, Guang-Cheng; Schwope, Axel; Ji, Li +3 more
Most young neutron stars belonging to the class of Central Compact Objects (CCOs) in supernova remnants do not have known periodicities. We investigated seven such CCOs to understand the common reasons for the absence of detected pulsations. Making use of XMM-Newton, Chandra, and NICER observations, we perform a systematic timing and spectral anal…
An extreme case of galaxy and cluster co-evolution at z = 0.7
Smail, I.; Koekemoer, A. M.; Richard, J. +3 more
We report the discovery of eMACS J0252.4-2100 (eMACS J0252), a massive and highly evolved galaxy cluster at z = 0.703. Our analysis of Hubble Space Telescope imaging and VLT/MUSE and Keck/DEIMOS spectroscopy of the system finds a high-velocity dispersion of 1020$^{+180}_{-190}$ km s-1 and a high (if tentative) X-ray luminosity of (1.2 ±…
Searching for the brightest stars in galaxies outside the Local Group
Tikhonov, Nikolay; Galazutdinova, Olga; Sholukhova, Olga +3 more
This paper introduces a technique for searching for bright massive stars in galaxies beyond the Local Group. To search for massive stars, we processed the results of stellar photometry from the Hubble Space Telescope (HST) images using the DAOPHOT and DOLPHOT packages. The results of such searches are demonstrated with examples of the galaxies DDO…
Does a Magnetosphere Protect the Ionosphere?
Gunell, Herbert; Maggiolo, Romain