Bean, Jacob L., Seifahrt, Andreas, Hartman, Henrik, Nilsson, Hampus, Wiedemann, Guenter, Reiners, Ansgar, ...
Radial velocities measured from near-infrared spectra are a potentially powerful tool to search for planets around cool stars and sub-stellar objects. However, no technique currently exists that...
Bean, Jacob L., Seifahrt, Andreas
We present a combined analysis of previously published high-precision radial velocities and astrometry for the GJ876 planetary system using a self-consistent model that accounts for the planet-planet...
Observation and modelling of dusty, low gravity L, and M dwarfs (2008)
Seifahrt, Andreas, Helling, Christiane, Burgasser, Adam J., Allers, Katelyn N., Cruz, Kelle L., Cushing, Michael C., ...
Observational facilities allow now the detection of optical and IR spectra of young M- and L-dwarfs. This enables empirical comparisons with old M- and L- dwarfs, and detailed studies in comparison...
Activity and rotation of low mass stars in young open clusters (2008)
Seifahrt, Andreas, Reiners, Ansgar, Scholz, Aleks, Basri, Gibor
We present first results from a multi-object spectroscopy campaign in IC2602, the Hyades, the Pleiades, and the Coma cluster using VLT/FLAMES. We analysed the data for radial velocity, rotational...
A search for wide brown dwarf companions to stars within 10pc (2008)
Treselj, Marin, Seifahrt, Andreas, Hodapp, Klaus-Werner, Bedalov, Ana, Mugrauer, Markus
We present the first results of a large imaging survey to identify wide brown dwarf companions to stars within 10 pc. We have performed a deep (H-band limit ~ 19.0 mag), wide field (up to 16x16...
Synergy of multifrequency studies from observations of NGC6334I (2008)
Seifahrt, Andreas, Thorwirth, Sven, Beuther, Henrik, Leurini, Silvia, Brogan, Crystal L, Hunter, Todd R, ...
We combine multifrequency observations from the millimeter to near infrared wavelengths that demonstrate the spatial distributions of H2, CO, and NH3 emission, which are all manifestations of various...
Seifahrt, Andreas, Kaeufl, Hans-Ulrich
High precision radial velocity (RV) measurements in the near infrared are on high demand, especially in the context of exoplanet search campaigns shifting their interest to late type stars in order...
Observational Consequences of the Recently Proposed Super-Earth Orbiting GJ436 (2008)
Bean, Jacob L., Seifahrt, Andreas
Ribas and collaborators have recently proposed that an additional, ~5 M_earth planet orbits the transiting planet host star GJ436. Long-term dynamical interactions between the two planets leading to...
Integral field spectroscopy of the GQ Lup companion (2008)
Nur wenige sehr junge und extrem massearme substellare Objekte sind zur Zeit bekannt. Ihr Entstehungsmechanismus ist nur unzureichend verstanden und umstritten. Gängige Entwicklungsmodelle...
Astrometric and photometric monitoring of GQ Lup and its sub-stellar companion (2008)
Neuhaeuser, Ralph, Mugrauer, Markus, Seifahrt, Andreas, Schmidt, Tobias, Vogt, Nikolaus
Neuhaeuser et al. (2005) presented direct imaging evidence for a sub-stellar companion to the young T Tauri star GQ Lup. Common proper motion was highly significant, but no orbital motion was...
Synergy of multi-frequency studies from observations of NGC 6334I (2008)
Seifahrt, Andreas, Thorwirth, Sven, Beuther, Henrik, Leurini, Silvia, Brogan, Crystal L., Hunter, Todd R., ...
We combine multi-frequency observations from the millimeter to near infrared wavelengths that demonstrate the spatial distributions of H2, CO, and NH3 emission, which are all manifestations of...
Probing micro-arcsec astrometry with NACO (2007)
Seifahrt, Andreas, Roell, Tristan, Neuhaeuser, Ralph
Relative astrometric measurements with a precision far better than 1 mas (milli-arcsec) are commonly regarded as the domain of interferometry. Pioneering work by Pravdo & Shaklan (1996), made in the...
Reiners, Ansgar, Seifahrt, Andreas, Käufl, Hans Ulrich, Siebenmorgen, Ralf, Smette, Alain
We show individual high resolution spectra of components A, B, and C of the nearby late-M type multiple system LHS 1070. Component A is a mid-M star, B and C are known to have masses at the threshold...
Siebenmorgen, Ralf, Smette, Alain, Käufl, Hans Ulrich, Seifahrt, Andreas, Uttenthaler, Stefan, Bik, Arjan, ...
Near-IR integral-field spectroscopy of the companion to GQ Lup (2006)
Seifahrt, Andreas, Neuhaeuser, Ralph, Hauschildt, Peter H.
The first substellar companion of possibly planetary mass around a normal star, GQ Lup, has been directly imaged (Neuhaeuser et al., 2005). Besides the unknown formation history, the mass of such an...
Detectability of planets in wide binaries by ground-based relative astrometry with AO (2006)
Neuhaeuser, Ralph, Seifahrt, Andreas, Roell, Tristan, Bedalov, Ana, Mugrauer, Markus
Many planet candidates have been detected by radial velocity variations of the primary star; they are planet candidates, because of the unknown orbit inclination. Detection of the wobble in the two...
The University of Hawaii Wide Field Imager (UHWFI) (2006)
Hodapp, Klaus W., Seifahrt, Andreas, Luppino, Gerard A., Wainscoat, Richard, Sousa, Ed, Yamada, Hubert, ...
The University of Hawaii Wide-Field Imager (UHWFI) is a focal compressor system designed to project the full half-degree field of the UH 2.2 m telescope onto the refurbished UH 8Kx8K CCD camera. The...
New brown dwarf companions to dM(e) stars (2005)
Seifahrt, Andreas, Mugrauer, Markus, Wiese, Manuela, Neuhaeuser, Ralph, Guenther, Eike W.
We present new astrometric and spectroscopic data to confirm two new M/L dwarf systems, G124-62 and LHS5166, and discuss the nature of a third system (LP261-75). Age and thus mass determinations of...
Seifahrt, Andreas, Guenther, Eike, Neuhaeuser, Ralph
We present astrometric and photometric measurements of the field binary L1 dwarf DENIS-P J1441-0945. Analysis of archival HST images and photometric parallax measurements give a distance of 34+/-7 pc...
Astrometric proof of companionship for the L dwarf companion candidate GJ 1048B (2004)
Seifahrt, Andreas, Neuhäuser, Ralph, Mugrauer, Markus
Gizis et al. (2001) reported a companion candidate of spectral type L1 near the K2 dwarf GJ 1048 using the Two Micron All-Sky Survey (2MASS). At that time it was not possible to verify companionship...