Low-resolution optical spectra of ultracool dwarfs with OSIRIS/GTC

Abstract

We present the results of low-resolution optical spectroscopy with OSIRIS/GTC (Optical System for Imaging and Low Resolution Integrated Spectroscopy / Gran Telescopio Canarias) for a sample of ultracool dwarfs. For a subsample of seven objects, based on 2MASS NIR photometric colours, a 'photometric' spectral type is determined and compared to the results of the optical spectroscopy. For the stars, showing H$\alpha$ line in emission, equivalent widths were measured, and the ratio of H$\alpha$ to bolometric luminosity were calculated. We find that two dwarfs show the presence of magnetic activity over long periods, LP 326-21 -- quasi-constant-like, and 2MASS J17071830+6439331 -- variable.

arXiv comment7 pages, 4 figures, 3 tables. arXiv admin note: text overlap with arXiv:astro-ph/0612604 by other authors

References in corpus (30)

• Constraining the Age-Activity Relation for Cool Stars: The SDSS DR5 Low-Mass Star Spectroscopic Sample
• New Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence
• Rotation and Activity in Mid-M to L Dwarfs
• Stellar SEDs from 0.3-2.5 Microns: Tracing the Stellar Locus and Searching for Color Outliers in SDSS and 2MASS
• Spectroscopic Properties of Cool Stars in the SDSS: An Analysis of Magnetic Activity and a Search for Subdwarfs
• The Brown Dwarf Kinematics Project (BDKP) I. Proper Motions and Tangential Velocities for a Large Sample of Late-type M, L and T Dwarfs
• A Spectroscopic Catalog of the Brightest (J<9) M Dwarfs in the Northern Sky
• The First Direct Measurements of Magnetic Fields on Very Low-Mass Stars
• Confirmation of the Electron Cyclotron Maser Instability as the Dominant Source of Radio Emission from Very Low Mass Stars and Brown Dwarfs
• Activity in Very Cool Stars: Magnetic Dissipation in late-M and L Dwarf Atmospheres
• A Volume-limited Sample of 63 M7-M9.5 Dwarfs II. Activity, magnetism, and the fade of the rotation-dominated dynamo
• Activity and Kinematics of Ultracool Dwarfs Including An Amazing Flare Observation
• The True Incidence of Magnetism among Field White Dwarfs
• The Spectra of T Dwarfs. II. Red Optical Data
• The Radio Activity-Rotation Relation of Ultracool Dwarfs
• Periodic Radio and H-alpha Emission from the L Dwarf Binary 2MASSW J0746425+200032: Exploring the Magnetic Field Topology and Radius of an L Dwarf
• Meeting the Cool Neighbors III: Spectroscopy of Northern NLTT Stars
• The White Dwarfs within 20 Parsecs of the Sun: Kinematics and Statistics
• Exploring the Local Milky Way: M Dwarfs as Tracers of Galactic Populations
• The χFactor: Determining the Strength of Activity in Low Mass Dwarfs
• Simultaneous Multi-Wavelength Observations of Magnetic Activity in Ultracool Dwarfs. I. The Complex Behavior of the M8.5 Dwarf TVLM513-46546
• Periodic Radio Emission from the M7 Dwarf 2MASS J13142039+1320011: Implications for the Magnetic Field Topology
• Sporadic Long-term Variability in Radio Activity from a Brown Dwarf
• Volume-limited radio survey of ultracool dwarfs
• A New Brown Dwarf Desert? A Scarcity of Wide Ultracool Binaries
• Variability and periodicity of field M dwarfs revealed by multichannel monitoring
• A Mini-survey of Ultracool Dwarfs at 4.9 GHz
• Steady and Transient Radio Emission from Ultracool Dwarfs
• Comparative analysis of two formation scenarios of bursty radio emission from ultracool dwarfs
• Modelling the radio pulses of an ultracool dwarf

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• The Field Substellar Mass Function Based on the Full-sky 20-pc Census of 525 L, T, and Y Dwarfs
• Preliminary Trigonometric Parallaxes of 184 Late-T and Y Dwarfs and an Analysis of the Field Substellar Mass Function into the "Planetary" Mass Regime
• A Volume-Limited Sample of Ultracool Dwarfs. I. Construction, Space Density, and a Gap in the L/T Transition
• A Panchromatic View of Brown Dwarf Aurorae
• The Ultracool SpeXtroscopic Survey. I. Volume-Limited Spectroscopic Sample and Luminosity Function of M7$-$L5 Ultracool Dwarfs
• Stars and brown dwarfs in the sigma Orionis cluster. IV. IDS/INT and OSIRIS/GTC spectroscopy and Gaia DR2 astrometry
• Optical Spectra of Ultracool Dwarfs with the Southern African Large Telescope
• The Occurrence Rate of Quiescent Radio Emission for Ultracool Dwarfs using a Generalized Semi-Analytical Bayesian Framework
• The Brown Dwarf Kinematics Project (BDKP). V. Radial and Rotational Velocities of T Dwarfs from Keck/NIRSPEC High-Resolution Spectroscopy
• Independent Study and Spectral Classification of a Sample of Poorly Studied High Proper Motion M-dwarf Candidate Stars