Model-Independent Diagnostics of Highly Reddened Milky Way Star Clusters: Age Calibration (2009)
Beletsky, Yuri, Carraro, Giovanni, Ivanov, Valentin D.
The next generation near- and mid-infrared Galactic surveys will yield a large number of new highly obscured star clusters. Detailed characterization of these new objects with spectroscopy is...
Near-infrared spectra of Galactic stellar clusters detected on Spitzer/GLIMPSE images (2009)
Messineo, Maria, Davies, Ben, Ivanov, Valentin D., Figer, Donald F., Schuller, Frederic, Habing, Harm J., ...
We present near-infrared spectroscopic observations of massive stars in three stellar clusters located in the direction of the inner Galaxy. One of them, the Quartet, is a new discovery while the...
Luminosity-Metallicity Relation for dIrr Galaxies in the Near-Infrared (2008)
Saviane, Ivo, Ivanov, Valentin D., Held, Enrico V., Alloin, Danielle, Rich, R. Michael, Bresolin, Fabio, ...
(abridged) The present work is a first step to collect homogeneous abundances and near-infrared (NIR) luminosities for a sample of dwarf irregular (dIrr) galaxies, located in nearby groups. The use...
Hoyer, Sergio, Alegria, Sebastian Ramirez, Ivanov, Valentin D., Minniti, Dante, Pietrzynski, Grzegorz, Ruiz, Maria Teresa, ...
We present precise new V, I, and K-band photometry for the planetary transit candidate star OGLE-TR-82. Good seeing V-band images acquired with VIMOS instrument at ESO VLT allowed us to measure...
Díaz, Rodrigo F., Ramírez, Sebastián, Fernández, José Miguel, Gallardo, José, Gieren, Wolfgang, Ivanov, Valentin D., ...
We present precise V and Ks-band transit photometry for the planetary host star OGLE-TR-113. Using the Ks-band photometry, we confirm the dwarf nature of OGLE-TR-113, and obtain new estimates for its...
Infrared Spectroscopy of the Ultra Low Mass Binary Oph 162225-240515 (2006)
Brandeker, Alexis, Jayawardhana, Ray, Ivanov, Valentin D., Kurtev, Radostin
Binary properties are an important diagnostic of the star and brown dwarf formation processes. While wide binaries appear to be rare in the sub-stellar regime, recent observations have revealed...
Spectroscopy of Young Planetary Mass Candidates with Disks (2006)
Jayawardhana, Ray, Ivanov, Valentin D.
It is now well established that many young brown dwarfs exhibit characteristics similar to classical T Tauri stars, including infrared excess from disks and emission lines related to accretion....
Ivanov, Valentin D., Nuernberger, D., Chauvin, G., Foellmi, C., Hartung, M., Huelamo, N., ...
The multiplicity of early-type stars is still not well established. The studies of individual star forming regions suggest a connection with the age and the environment. To fill in this gap, we...
Optical and near-infrared observations of the peculiar Type la supernova 1999ac (2006)
Phillips, Mark M., Krisciunas, Kevin, Suntzeff, Nicholas B., Abraham, R. G., Beckett, M. G., Bonati, Marco, ...
We present 39 nights of optical photometry, 34 nights of IR photometry, and 4 nights of optical spectroscopy of the Type la supernova 1999ac. This supernova was discovered 2 weeks before maximum...
Optical and near-infrared observations of the peculiar Type la supernova 1999ac (2006)
Phillips, Mark M., Krisciunas, Kevin, Suntzeff, Nicholas B., Abraham, R. G., Beckett, M. G., Bonati, Marco, ...
We present 39 nights of optical photometry, 34 nights of IR photometry, and 4 nights of optical spectroscopy of the Type la supernova 1999ac. This supernova was discovered 2 weeks before maximum...
Ivanov, Valentin D., Chauvin, G., Foellmi, C., Hartung, M., Huelamo, N., Melo, C., ...
The multiplicity of early-type stars is still not well established. The derived binary fraction is different for individual star forming regions, suggesting a connection with the age and the...
Ivanov, Valentin D., Kurtev, Radostin, Borissova, Jordanka
Deep near infrared photometry of the newly discovered Galactic globular Cluster GLIMPSE-C01 is reported. We derived for the first time the metal abundance of this object from the slope of the RGB:...
A Medium-Resolution Near-Infrared Spectral Library of Late Type Stars: I (2003)
Ivanov, Valentin D., Rieke, Marcia J., Engelbracht, Charles W., Alonso-Herrero, Almudena, Rieke, George H., Luhman, Kevin L.
We present an empirical infrared spectral library of medium resolution (R~2000-3000) H (1.6 micron) and K (2.2 micron) band spectra of 218 red stars, spanning a range of [Fe/H] from ~-2.2 to ~+0.3....
Spectral Energy Distributions of Seyfert Nuclei (2003)
Alonso-Herrero, Almudena, Quillen, Alice C., Rieke, George H., Ivanov, Valentin D., Efstathiou, Andreas
We present nuclear spectral energy distributions (SEDs) in the range 0.4-16micron for an expanded CfA sample of Seyfert galaxies. The spectral indices from 1-16micron range from alpha_IR 0.9 to 3.8....
T Tauri Stars in the Small Magellanic Cloud (2002)
Ivanov, Valentin D., Jayawardhana, Ray
The Small Magellanic Cloud (SMC) is an excellent laboratory to study the formation of solar-mass stars in a low-metallicity environment, similar to the conditions expected in the early phases of...
Deep I-band Imaging of z=5.99 Quasar (2002)
Deep I-band imaging was carried out to search for the optical counterpart of the X-ray jet candidate near SDSS 1306+0356, reported by Schwartz (2002, astro-ph/0202190). The data suggest that the...
Ivanov, Valentin D., Borissova, Jordanka
The near-infrared behavior of the red giant branch (RGB hereafter) as a function of abundance is examined with an unprecedented large sample of 27 Galactic globular clusters with Two Micron All Sky...
Optical and Infrared Spectroscopy of SN 1999ee and SN 1999ex (2002)
Hamuy, Mario, Maza, Jose, Pinto, Philip A., Phillips, M. M., Suntzeff, Nicholas B., Blum, R. D., ...
We report optical and infrared spectroscopic observations of the Type Ia SN 1999ee and the Type Ib/c SN 1999ex, both of which were hosted by the galaxy IC 5179. For SN 1999ee we obtained a continuous...
Deep Near Infrared Photometry of New Galactic Globular Clusters (2000)
Ivanov, Valentin D., Borissova, Jordanka, Vanzi, Leonardo
We present a preliminary report on the first deep infrared photometry of 2MASS GC01 and 2MASS GC02 (GC01 and GC02 hereafter) - new Galactic globular cluster (GC) candidates, discovered by the 2MASS....
Testing the AGN-Starburst Connection in Seyfert Galaxies (2000)
Ivanov, Valentin D., Rieke, George H., Groppi, Christopher E., Alonso-Herrero, Almudena, Rieke, Marcia J., Engelbracht, C. W.
We use the CO band at 2.3 micron to constrain the populations of young stars in the central regions of Seyfert galaxies. We report new CO band spectroscopy of 46 Seyfert galaxies. In most cases, the...
Ivanov, Valentin D., Hamuy, Mario, Pinto, Philip A.
We study the properties of Type Ia Supernovae (SNe Ia) as functions of the radial distance from their host galaxy centers. Using a sample of 62 SNe Ia with reliable luminosity, reddening, and decline...
Ivanov, Valentin D., Borissova, Jordanka, Alonso-Herrero, Almudena, Russeva, Tatiana
Infrared JKs-band photometry of the Galactic globular clusters M15 and, for the first time, M56 is presented. We estimated the reddening (E(B-V)=0.18+/-0.08 mag) and distance modulus...
An Infrared Determination of the Reddening and Distance to Dwingeloo 1 (1999)
Ivanov, Valentin D., Alonso-Herrero, Almudena, Rieke, Marcia J., McCarthy, Don
We present for the first time infrared observations of the nearby highly obscured galaxy Dwingeloo 1 (Dw1), including deep H-band imaging covering a total of 4.9x4.9 arcmin, together with J and Ks...