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The Physical Properties and Effective Temperature Scale of O-type Stars as a Function of Metallicity. III. More Results from the Magellanic Clouds
Philip Massey, Amanda M. Zangari, Nidia I. Morrell +4
In order to better determine the physical properties of hot, massive stars as a function of metallicity, we obtained very high SNR optical spectra of 26 O and early B stars in the…
Do the photometric colors of Type II-P Supernovae allow accurate determination of host galaxy extinction?
Kevin Krisciunas, Mario Hamuy, Nicholas B. Suntzeff +10
We present infrared photometry of SN 1999em, plus optical photometry, infrared photometry, and optical spectroscopy of SN 2003hn. Both objects were Type II-P supernovae. The V-[RIJ…
A New Distance to The Antennae Galaxies (NGC 4038/39) Based on the Type Ia Supernova 2007sr
Francois Schweizer, Christopher R. Burns, Barry F. Madore +13
Traditionally, the distance to NGC 4038/39 has been derived from the systemic recession velocity, yielding about 20 Mpc for H_0 = 72 km/s/Mpc. Recently, this widely adopted distanc…
A Three-Decade Outburst of the LMC Luminous Blue Variable R127 Draws to a Close
Nolan R. Walborn, Otmar Stahl, Roberto C. Gamen +7
The paradigmatic Luminous Blue Variable R127 in the Large Magellanic Cloud has been found in the intermediate, peculiar early-B state, and substantially fainter in visual light, si…
A Spectroscopic Survey of WNL Stars in the LMC: General Properties and Binary Status
O. Schnurr, A. F. J. Moffat, N. St-Louis +2
We report the results of an intense, spectroscopic survey of all 41 late-type, nitrogen-rich Wolf-Rayet (WR) stars in the Large Magellanic Cloud (LMC) observable with ground-based…
Spectroscopic monitoring of Southern Galactic O and WN stars: State of the Art in 2007
R. Gamen, R. Barba, N. Morrell +5
We are conducting a spectroscopic monitoring of O and WN -type stars in our Galaxy. In this work, we summarize some of our first results related to the search for radial-velocity v…
The Massive Star Content of NGC 3603
Nicholas W. Melena, Philip Massey, Nidia I. Morrell +1
We investigate the massive star content of NGC 3603, the closest known giant H II region. We have obtained spectra of 26 stars in the central cluster using the Baade 6.5-m telescop…
The underluminous Type Ia Supernova 2005bl and the class of objects similar to SN 1991bg
S. Taubenberger, S. Hachinger, G. Pignata +24
Optical observations of the Type Ia supernova (SN Ia) 2005bl in NGC 4070, obtained from -6 to +66 d with respect to the B-band maximum, are presented. The photometric evolution is…
A multispectral view of the periodic events in eta Carinae
A. Damineli, D. J. Hillier, M. F. Corcoran +13
A full description of the 5.5-yr low excitation events in Eta Carinae is presented. We show that they are not as simple and brief as previously thought, but a combination of two co…
Optical/Infrared Observations of the Anomalous X-ray Pulsar 1E 1048.1-5937 During Its 2007 X-Ray Flare
Z. Wang, C. Bassa, V. M. Kaspi +2
We report on optical and infrared observations of the anomalous X-ray pulsar (AXP) 1E 1048.1-5937, made during its ongoing X-ray flare which started in 2007 March. We detected the…
The Peculiar SN 2005hk: Do Some Type Ia Supernovae Explode as Deflagrations?
M. M. Phillips, W. Li, J. A. Frieman +41
We present extensive u'g'r'i'BVRIYJHKs photometry and optical spectroscopy of SN 2005hk. These data reveal that SN 2005hk was nearly identical in its observed properties to SN 2002…
Limits to Transits of the Neptune-mass planet orbiting Gl 581
Mercedes Lopez-Morales, Nidia I. Morrell, R. Paul Butler +1
We have monitored the Neptune-mass exoplanet-hosting M-dwarf Gl 581 with the 1m Swope Telescope at Las Campanas Observatory over two predicted transit epochs. A neutral density fil…
The Carnegie Supernova Project: The Low-Redshift Survey
Mario Hamuy, Gastón Folatelli, Nidia I. Morrell +15
Supernovae are essential to understanding the chemical evolution of the Universe. Type Ia supernovae also provide the most powerful observational tool currently available for study…
The infrared Hourglass cluster in M8
J. Arias, R. Barba, J. Maiz Apellaniz +2
A detailed study of the Hourglass Nebula in the M8 star forming region is presented. The study is mainly based on recent subarcsec-resolution JHKs images taken at Las Campanas Obse…
A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds
Nolan R. Walborn, Nidia I. Morrell, Ian D. Howarth +4
From a survey of the 3400 A region in the earliest O-type spectra, we have found that two of the four O2 giants observed in the LMC have the OIV lines there stronger than the NIV,…
Evidence for an asymptotic giant branch star in the progenitor system of a type Ia supernova
Mario Hamuy, M. M. Phillips, Nicholas B. Suntzeff +8
A type Ia supernova (SN Ia), one of the two main classes of exploding stars, is recognized by the absence of hydrogen and the presence of elements such as silicon and sulphur in it…
LSS 1135: an O-Type Spectroscopic Binary in the galactic OB association Bochum 7
Mariela Corti, Virpi Niemela, Nidia Morrell
From radial velocities derived from optical spectroscopic observations performed at CTIO, Chile, and CASLEO, Argentina, we have discovered that LSS 1135 is a single--lined O-type b…
The massive double-lined O-type binary HD 165052
J. I. Arias, N. I. Morrell, R. H. Barba +4
We present a new optical spectroscopic study of the O-type binary HD 165052 based on high- and intermediate-resolution CCD observations. We re-investigated the spectral classificat…
Calculation of the Masses of the Binary Star HD 93205 by Application of the Theory of the Apsidal Motion
O. G. Benvenuto, A. M. Serenelli, L. G. Althaus +2
We present a method to calculate masses for components of both eclipsing and non-eclipsing binary systems as long as their apsidal motion rates are available. The method is based o…
Optical spectroscopy of X-MEGA targets I. CPD -59 2635: A New Double-Lined O type Binary in the Carina Nebula
J. F. Albacete Colombo, N. I. Morrell, V. S. Niemela +1
Optical spectroscopy of CPD -59 2635, one of the O-type stars in the open cluster Trumpler 16 in the Carina Nebula, reveals this star to be a double-lined binary system. We have ob…
Determination of Masses and Radii of the Massive Eclipsing Binary System HV 2543 in the Large Magellanic Cloud
P. G. Ostrov, E. Lapasset, N. I. Morrell
We present a V light curve of the eclipsing binary system HV 2543 (Sk-67 117) in the Large Magellanic Cloud based on CCD images acquired between the years 1995 and 1998. We have an…