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Bond H.E.,US Space Telescope Science Institute | Bond H.E.,9615 Labrador Lane | Kasliwal M.M.,Carnegie Institution for Science
Publications of the Astronomical Society of the Pacific | Year: 2012

NSV 11749 is a little-studied variable star, discovered by W. J. Luyten, which had a long-duration outburst around the year 1903, reaching blue magnitude 12.5 at maximum. Following the outburst, it has apparently been quiescent at about blue magnitude 17 for the past century. It was recently suggested that NSV 11749 may have been a low- or intermediate-mass star that underwent a final helium shell flash, making it temporarily a "born-again" red giant. If so, it would be only the fourth known member of this class, along with V605 Aql, FG Sge, and V4334 Sgr. However, our newly obtained optical and near-IR spectra of the object show that it is instead a symbiotic binary, with strong Balmer and He I-II emission lines, combined with a cool red-giant companion of spectral type M1-2 III. The 1903 outburst was most likely a symbiotic nova event, of which less than a dozen are known at present. © 2012. The Astronomical Society of the Pacific. Source

Walter F.M.,State University of New York at Stony Brook | Battisti A.,State University of New York at Stony Brook | Battisti A.,University of Massachusetts Amherst | Towers S.E.,State University of New York at Stony Brook | And 4 more authors.
Publications of the Astronomical Society of the Pacific | Year: 2012

We introduce the Stony Brook/SMARTS Atlas of (mostly) Southern Novae. This atlas contains both spectra and photometry obtained since 2003. The data archived in this atlas will facilitate systematic studies of the nova phenomenon and correlative studies with other comprehensive data sets. It will also enable detailed investigations of individual objects. In making the data public we hope to engender more interest on the part of the community in the physics of novae. The atlas is NovaAtlas/. © The Astronomical Society of the Pacific. All rights reserved. Source

Farihi J.,University of Cambridge | Farihi J.,University of Leicester | Bond H.E.,US Space Telescope Science Institute | Bond H.E.,Pennsylvania State University | And 7 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2013

This paper presents newobservations of the planet-hosting, visual binary GJ 86 (HR637) using the Hubble Space Telescope. Ultraviolet and optical imaging with WFC3 confirms the stellar companion is a degenerate star and indicates the binary semimajor axis is larger than previous estimates, with a ≥ 28 au. Optical STIS spectroscopy of the secondary reveals a helium-rich white dwarf with C2 absorption bands and Teff = 8180 K, thus making the binary system rather similar to Procyon. Based on the 10.8 pc distance, the companion has 0.59M and descended from a main-sequence A star of 1.9M with an original orbital separation a ≥ 14 au. If the giant planet is coplanar with the binary, the mass of GJ 86Ab is between 4.4 and 4.7MJup. The similarity of GJ 86 and Procyon prompted a re-analysis of the white dwarf in the latter system, with the tentative conclusion that Procyon hosts a planetesimal population. The periastron distance in Procyon is 20 per cent smaller than in α Cen AB, but the metal-enriched atmosphere of Procyon B indicates that the planet formation process minimally attained 25 km bodies, if not small planets as in α Cen. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Source

Bond H.E.,US Space Telescope Science Institute | Bond H.E.,Pennsylvania State University | Bond H.E.,9615 Labrador Lane | Nelan E.P.,US Space Telescope Science Institute | And 3 more authors.
Astrophysical Journal Letters | Year: 2013

HD 140283 is an extremely metal-deficient and high-velocity subgiant in the solar neighborhood, having a location in the Hertzsprung-Russell diagram where absolute magnitude is most sensitive to stellar age. Because it is bright, nearby, unreddened, and has a well-determined chemical composition, this star avoids most of the issues involved in age determinations for globular clusters. Using the Fine Guidance Sensors on the Hubble Space Telescope, we have measured a trigonometric parallax of 17.15 ± 0.14 mas for HD 140283, with an error one-fifth of that determined by the Hipparcos mission. Employing modern theoretical isochrones, which include effects of helium diffusion, revised nuclear reaction rates, and enhanced oxygen abundance, we use the precise distance to infer an age of 14.46 ± 0.31 Gyr. The quoted error includes only the uncertainty in the parallax, and is for adopted surface oxygen and iron abundances of [O/H] = -1.67 and [Fe/H] = -2.40. Uncertainties in the stellar parameters and chemical composition, especially the oxygen content, now contribute more to the error budget for the age of HD 140283 than does its distance, increasing the total uncertainty to about ±0.8 Gyr. Within the errors, the age of HD 140283 does not conflict with the age of the Universe, 13.77 ± 0.06 Gyr, based on the microwave background and Hubble constant, but it must have formed soon after the big bang. © 2013. The American Astronomical Society. All rights reserved.. Source

Clayton G.C.,Louisiana State University | Bond H.E.,US Space Telescope Science Institute | Bond H.E.,Pennsylvania State University | Bond H.E.,9615 Labrador Lane | And 8 more authors.
Astrophysical Journal | Year: 2013

New imaging of V605 Aql, was obtained in 2009 with HST/WFPC2, which had a nova-like outburst in 1919, and is located at the center of the planetary nebula (PN), A58. This event has long been ascribed to a final helium shell flash, but it has been suggested recently that it may instead have been an ONe nova. The new images provide an 18 yr baseline for the expansion of the ejecta from the 1919 event. In addition, the central star has been directly detected in the visible for the first time since 1923, when it faded from sight due to obscuration by dust. The expansion of the ejecta has a velocity of ∼200 km s-1, and an angular expansion rate of ∼10 mas yr-1, consistent with a 1919 ejection. This implies a geometric distance of 4.6 kpc for V605 Aql, consistent with previous estimates. The gas mass in the central knot of ejecta was previously estimated to be 5 × 10-5 M. It is estimated that warm dust associated with this gas has a mass of ∼10 -5 M. There is also evidence for a significant amount, 10 -3 M, of cold (75 K) dust, which may be associated with its PN. The knot ejected in 1919 is asymmetrical and is approximately aligned with the asymmetry of the surrounding PN. Polarimetric imaging was obtained to investigate whether the 2001 spectrum of V605 Aql was obtained primarily in scattered light from dust in the central knot, but the signal-to-noise in the data was insufficient to measure the level of polarization. © 2013. The American Astronomical Society. All rights reserved.. Source

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