Search Publications
Investigating the mass of the intermediate mass black hole candidate HLX-1 with the slimbh model
Godet, Olivier; Barret, Didier; Webb, Natalie +2 more
In this paper we present a comprehensive study of the mass of the intermediate mass black hole candidate HLX-1 in the galaxy ESO 243-49. We analyse the continuum X-ray spectra collected by Swift, XMM-Newton, and Chandra with the slim disc model, slimbh, and estimate the black hole mass for the full range of inclination (inc = 0°-85°) and spin (a
A Search for Companions to Brown Dwarfs in the Taurus and Chamaeleon Star-Forming Regions
Todorov, K. O.; Luhman, K. L.; Konopacky, Q. M. +5 more
We have used WFPC2 on board the Hubble Space Telescope to obtain images of 47 members of the Taurus and Chamaeleon I star-forming regions that have spectral types of M6-L0 (M ~ 0.01-0.1 M ⊙). An additional late-type member of Taurus, FU Tau (M7.25+M9.25), was also observed with adaptive optics at Keck Observatory. In these images, we ha…
Observational Studies on the Near-infrared Unidentified Emission Bands in Galactic H II Regions
Onaka, Takashi; Sakon, Itsuki; Shimonishi, Takashi +4 more
Using a large collection of near-infrared spectra (2.5-5.4 µm) of Galactic H II regions and H II region-like objects, we perform a systematic investigation of astronomical polycyclic aromatic hydrocarbon (PAH) features. Thirty-six objects were observed using the infrared camera on board the AKARI satellite as a part of a director's time prog…
Herschel Planetary Nebula Survey (HerPlaNS). First detection of OH+ in planetary nebulae
Sahai, R.; Izumiura, H.; Kastner, J. H. +15 more
Aims: We report the first detections of OH+ emission in planetary nebulae (PNe).
Methods: As part of an imaging and spectroscopy survey of 11 PNe in the far-IR using the PACS and SPIRE instruments aboard the Herschel Space Observatory, we performed a line survey in these PNe over the entire spectral range between 51µm an…
The Spatially Resolved Bipolar Nebula of Sakurai's Object
Hinkle, Kenneth H.; Joyce, Richard R.
Sakurai's object (V4334 Sgr), the final flash object discovered in the mid-1990s, underwent rapid cooling during the first decade of the 21st century becoming as faint as K ~ 25. This stage of evolution has ceased. Between observations in 2010 September and 2013 April V4334 Sgr brightened >2 mag to K = 14.2 and the effective temperature increas…
Areas of Polar Coronal Holes from 1996 Through 2010
Karna, N.; Hess Webber, S. A.; Pesnell, W. D. +1 more
Polar coronal holes (PCHs) trace the magnetic variability of the Sun throughout the solar cycle. Their size and evolution have been studied as proxies for the global magnetic field. We present measurements of the PCH areas from 1996 through 2010, derived from an updated perimeter-tracing method and two synoptic-map methods. The perimeter-tracing m…
Radio-Optical Reference Frame Link Using the U.S. Naval Observatory Astrograph and Deep CCD Imaging
Zacharias, N.; Zacharias, M. I.
Between 1997 and 2004 several observing runs were conducted, mainly with the CTIO 0.9 m, to image International Celestial Reference Frame (ICRF) counterparts (mostly QSOs) in order to determine accurate optical positions. Contemporary to these deep CCD images, the same fields were observed with the U.S. Naval Observatory astrograph in the same ban…
Close Companions to Two High-redshift Quasars
Strauss, Michael A.; Fan, Xiaohui; Jiang, Linhua +5 more
We report the serendipitous discoveries of companion galaxies to two high-redshift quasars. SDSS J025617.7+001904 is a z = 4.79 quasar included in our recent survey of faint quasars in the SDSS Stripe 82 region. The initial MMT slit spectroscopy shows excess Lyα emission extending well beyond the quasar's light profile. Further imaging and spectro…
Single field inflation with modulated potential in light of Planck and BICEP2
Wan, Youping; Li, Siyu; Li, Mingzhe +3 more
The recently released BICEP2 data detected the primordial B-mode polarization in the cosmic microwave background (CMB) map which strongly supports for a large tensor-to-scalar ratio, and, thus, is found to be in tension with the Planck experiment with no evidence of primordial gravitational waves. Such an observational tension, if confirmed by for…
Signatures of the non-Maxwellian κ-distributions in optically thin line spectra. I. Theory and synthetic Fe IX-XIII spectra
Mason, H. E.; Del Zanna, G.; Dzifčáková, E. +1 more
Aims: We investigate the possibility of diagnosing the degree of departure from the Maxwellian distribution using single-ion spectra originating in astrophysical plasmas in collisional ionization equilibrium.
Methods: New atomic data for excitation of Fe ix - Fe xiii are integrated under the assumption of a κ-distribution of electron ene…