Search Publications
Evidence for variability time-scale-dependent UV/X-ray delay in Seyfert 1 AGN NGC 7469
Peterson, Bradley M.; Horne, Keith; Gültekin, Kayhan +5 more
Using a month-long X-ray light curve from RXTE/PCA and 1.5 month-long UV continuum light curves from IUE spectra in 1220-1970 Å, we performed a detailed time-lag study of the Seyfert 1 galaxy NGC 7469. Our cross-correlation analysis confirms previous results showing that the X-rays are delayed relative to the UV continuum at 1315 Šby 3.49 ± 0.22 d…
Atmospheric compositions and observability of nitrogen-dominated ultra-short-period super-Earths
Mollière, Paul; Tsai, Shang-Min; Miguel, Yamila +1 more
We explore the chemistry and observability of nitrogen-dominated atmospheres for ultra-short-period super-Earths. We base the assumption that super-Earths could have nitrogen-filled atmospheres on observations of 55 Cancri e that favour a scenario with a high-mean-molecular-weight atmosphere. We take Titan's elemental budget as our starting point …
Fundamental effective temperature measurements for eclipsing binary stars - I. Development of the method and application to AI Phoenicis
Maxted, P. F. L.; Smalley, B.; Miller, N. J.
Stars with accurate and precise effective temperature (Teff) measurements are needed to test stellar atmosphere models and calibrate empirical methods to determine Teff. There are few standard stars currently available to calibrate temperature indicators for dwarf stars. Gaia parallaxes now make it possible, in principle, to …
Regulation of accretion by its outflow in a symbiotic star: the 2016 outflow fast state of MWC 560
Sokoloski, J. L.; Luna, G. J. M.; Munari, U. +11 more
How are accretion discs affected by their outflows? To address this question for white dwarfs accreting from cool giants, we performed optical, radio, X-ray, and ultraviolet observations of the outflow-driving symbiotic star MWC 560 (≡V694 Mon) during its 2016 optical high state. We tracked multi-wavelength changes that signalled an abrupt increas…
Mode identification in three pulsating hot subdwarfs observed with TESS satellite
Heber, U.; Irrgang, A.; Raddi, R. +12 more
We report on the detection of pulsations of three pulsating subdwarf B stars observed by the Transiting Exoplanet Survey Satellite (TESS) satellite and our results of mode identification in these stars based on an asymptotic period relation. SB 459 (TIC 067584818), SB 815 (TIC 169285097), and PG 0342 + 026 (TIC 457168745) have been monitored durin…
The 2019 eruption of recurrent nova V3890 Sgr: observations by Swift, NICER, and SMARTS
Ness, J. -U.; Orio, M.; Osborne, J. P. +6 more
V3890 Sgr is a recurrent nova that has been seen in outburst three times so far, with the most recent eruption occurring on 2019 August 27 UT. This latest outburst was followed in detail by the Neil Gehrels Swift Observatory, from less than a day after the eruption until the nova entered the Sun observing constraint, with a small number of additio…
Planetary nebulae with Wolf-Rayet-type central stars - I. The case of the high-excitation NGC 2371
Guerrero, M. A.; Toalá, J. A.; Todt, H. +4 more
We present the analysis of the planetary nebula (PN) NGC 2371 around the [Wolf-Rayet] (WR) star WD 0722+295. Our Isaac Newton Telescope intermediate dispersion spectrograph spectra, in conjunction with archival optical and ultraviolet images, unveil in unprecedented detail the high ionization of NGC 2371. The nebula has an apparent multipolar morp…
The 2016 January eruption of recurrent Nova LMC 1968
Soszyński, I.; Udalski, A.; Szymański, M. K. +23 more
We present a comprehensive review of all observations of the eclipsing recurrent Nova LMC 1968 in the Large Magellanic Cloud which was previously observed in eruption in 1968, 1990, 2002, 2010, and most recently in 2016. We derive a probable recurrence time of 6.2 ± 1.2 yr and provide the ephemerides of the eclipse. In the ultraviolet-optical-IR p…
The nature of the photometric variability of HgMn stars: a test of simulated light curves of φ Phe against the TESS data
Krtička, Jiří; Korhonen, Heidi; Prvák, Milan
The inhomogeneous surface distribution of heavy elements is known to cause periodic light variability of magnetic chemically peculiar stars. It is unclear to what extent the same paradigm applies to mercury-manganese (HgMn) stars. We aim to model the photometric variability of the HgMn star φ Phe using abundance maps obtained from high-resolution …
The Bubble Nebula NGC 7635 - testing the wind-blown bubble theory
Chu, Y. -H.; Guerrero, M. A.; Toalá, J. A. +5 more
We present a multiwavelength study of the iconic Bubble Nebula (NGC 7635) and its ionizing star BD+60○2522. We obtained XMM-Newton EPIC X-ray observations to search for extended X-ray emission as in other similar wind-blown bubbles around massive stars. We also obtained San Pedro Mártir spectroscopic observations with the Manchester Ech…