Search Publications
Detection of the Ultraviolet Spectrum of the Hot Subdwarf Companion of 60 Cygni (B1 Ve) from a Survey of IUE Spectra of Be Stars
Gies, Douglas R.; Wang, Luqian; Peters, Geraldine J.
We used archival International Ultraviolet Explorer (IUE) high-dispersion, short wavelength spectra data to search for evidence of the spectra of hot subdwarf companions of six rapidly rotating Be stars in binary systems. We searched for the signature of a hot companion through an analysis of the cross-correlation functions (CCFs) of observed and …
The Massive CO White Dwarf in the Symbiotic Recurrent Nova RS Ophiuchi
Mikołajewska, Joanna; Shara, Michael M.
If accreting white dwarfs (WDs) in binary systems are to produce type Ia supernovae (SNe Ia), they must grow to nearly the Chandrasekhar mass and ignite carbon burning. Proving conclusively that a WD has grown substantially since its birth is a challenging task. Slow accretion of hydrogen inevitably leads to the erosion, rather than the growth of …
Extending the Calibration of C IV-based Single-epoch Black Hole Mass Estimators for Active Galactic Nuclei
Treu, Tommaso; Barth, Aaron J.; Assef, Roberto J. +5 more
We provide an updated calibration of C IV λ 1549 broad emission line-based single-epoch (SE) black hole (BH) mass estimators for active galactic nuclei (AGNs) using new data for six reverberation-mapped AGNs at redshift z=0.005{--}0.028 with BH masses (bolometric luminosities) in the range {10}6.5{--}{10}7.5 {M}⊙ …
Modifying the Standard Disk Model for the Ultraviolet Spectral Analysis of Disk-dominated Cataclysmic Variables. I. The Novalikes MV Lyrae, BZ Camelopardalis, and V592 Cassiopeiae
Blair, William P.; Sion, Edward M.; Balman, Şölen +1 more
The standard disk is often inadequate to model disk-dominated cataclysmic variables (CVs) and generates a spectrum that is bluer than the observed UV spectra. X-ray observations of these systems reveal an optically thin boundary layer (BL) expected to appear as an inner hole in the disk. Consequently, we truncate the inner disk. However, instead o…
Diffuse Interstellar Bands and the Ultraviolet Extinction Curves: The Missing Link Revisited
Li, Aigen; Xiang, F. Y.; Zhong, J. X.
A large number of interstellar absorption features at ∼4000 Å-1.8 µm, known as the “diffuse interstellar bands” (DIBs), remains unidentified. Most recent works relate them to large polycyclic aromatic hydrocarbon (PAH) molecules or ultrasmall carbonaceous grains which are also thought to be responsible for the 2175 \mathringA extinction bump…
Observational Evidence Linking Interstellar UV Absorption to PAH Molecules
Behar, Ehud; Brosch, Noah; Tielens, Alexander G. G. M. +2 more
The 2175 Å UV extinction feature was discovered in the mid-1960s, yet its physical origin remains poorly understood. One suggestion is absorption by polycyclic aromatic hydrocarbon (PAH) molecules, which is supported by theoretical molecular structure computations and by laboratory experiments. PAHs are positively detected by their 3.3, 6.2, 7.7, …
No Neon, but Jets in the Remarkable Recurrent Nova M31N 2008-12a?—Hubble Space Telescope Spectroscopy of the 2015 Eruption
Ness, J. -U.; Henze, M.; Shafter, A. W. +14 more
The 2008 discovery of an eruption of M31N 2008-12a began a journey on which the true nature of this remarkable recurrent nova continues to be revealed. M31N 2008-12a contains a white dwarf (WD) close to the Chandrasekhar limit, accreting at a high rate from its companion, and undergoes thermonuclear eruptions that are observed yearly and may even …
Masses of the Planetary Nebula Central Stars in the Galactic Globular Cluster System from HST Imaging and Spectroscopy
Bond, Howard E.; De Marco, Orsola; Lanz, Thierry +4 more
The globular cluster (GC) system of our Galaxy contains four planetary nebulae (PNe): K 648 (or Ps 1) in M15, IRAS 18333-2357 in M22, JaFu 1 in Pal 6, and JaFu 2 in NGC 6441. Because single-star evolution at the low stellar mass of present-epoch GCs was considered incapable of producing visible PNe, their origin presented a puzzle. We imaged the P…
A Spectroscopic Orbit for the Late-type Be Star β CMi
Wang, Luqian; Klement, Robert; Richardson, Noel D. +12 more
The late-type Be star β CMi is remarkably stable compared to other Be stars that have been studied. This has led to a realistic model of the outflowing Be disk by Klement et al. These results showed that the disk is likely truncated at a finite radius from the star, which Klement et al. suggest is evidence for an unseen binary companion in orbit. …
Outflow and Metallicity in the Broad-Line Region of Low-Redshift Active Galactic Nuclei
Nagao, Tohru; Woo, Jong-Hak; Shin, Jaejin
Outflows in active galactic nuclei (AGNs) are crucial to understand in investigating the co-evolution of supermassive black holes (SMBHs) and their host galaxies since outflows may play an important role as an AGN feedback mechanism. Based on archival UV spectra obtained with the Hubble Space Telescope and IUE, we investigate outflows in the broad…