Search for radial velocity variations in eight M-dwarfs with NIRSPEC/Keck II

Rodler, F.; Deshpande, Rohit; Osorio, M. R. Zapatero; Martín, E. L.; Montgomery, M. M.; Burgo, C. del; Creevey, O.

doi:10.1051/0004-6361/201117577

Cited by 16 publications

(19 citation statements)

References 31 publications

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“…We found these measurements, with uncertainties ranging from 0.5 to 0.9 km s −1 , were all consistent, albeit with lower precision, with those reported in Blake et al (2010) to within 1.6σ . While a forward-modeling approach would have likely produced better precision, our uncertainties are nevertheless roughly equivalent to contemporary NIRSPEC RV measurements of very cool dwarfs (e.g., Prato et al 2002;Zapatero Osorio et al 2007;Blake et al 2008Blake et al , 2010Rice et al 2010;Rodler et al 2012). Table 9 lists the final RV measurements for SDSS J0006−0852 for each epoch.…”

Section: Radial Velocity Measurementsmentioning

confidence: 70%

Discovery of a Very Low Mass Triple With Late-M and T Dwarf Components: Lp 704-48/SDSS J0006–0852ab

Burgasser

Luk

Dhital

et al. 2012

ApJ

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We report the identification of the M9 dwarf SDSS J000649.16−085246.3 as a spectral binary and radial velocity (RV) variable with components straddling the hydrogen-burning mass limit. Low-resolution near-infrared spectroscopy reveals spectral features indicative of a T dwarf companion, and spectral template fitting yields component types of M8.5 ± 0.5 and T5 ± 1. High-resolution near-infrared spectroscopy with Keck/NIRSPEC reveals pronounced RV variations with a semi-amplitude of 8.2 ± 0.4 km s −1 . From these we determine an orbital period of 147.6 ± 1.5 days and eccentricity of 0.10 ± 0.07, making SDSS J0006−0852AB the third tightest very low mass binary known. This system is also found to have a common proper motion companion, the inactive M7 dwarf LP 704-48, at a projected separation of 820 ± 120 AU. The lack of Hα emission in both M dwarf components indicates that this system is relatively old, as confirmed by evolutionary model analysis of the tight binary. LP 704-48/SDSS J0006−0852AB is the lowest-mass confirmed triple identified to date, and one of only seven candidate and confirmed triples with total masses below 0.3 M currently known. We show that current star and brown dwarf formation models cannot produce triple systems like LP 704-48/SDSS J0006−0852AB, and we rule out Kozai-Lidov perturbations and tidal circularization as a viable mechanism to shrink the inner orbit. The similarities between this system and the recently uncovered low-mass eclipsing triples NLTT 41135AB/41136 and LHS 6343ABC suggest that substellar tertiaries may be common in wide M dwarf pairs.

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Section: Radial Velocity Measurementsmentioning

confidence: 70%

Discovery of a Very Low Mass Triple With Late-M and T Dwarf Components: Lp 704-48/SDSS J0006–0852ab

Burgasser

Luk

Dhital

et al. 2012

ApJ

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“…Radial-velocity measurements of UCDs were used to exclude a large population of giant planets 2 Jupiter-mass (M J ) on very tight orbits <0.05 AU (Blake et al 2010;Rodler et al 2012). At wider separations 2 AU, direct-imaging searches equally excluded a large population of giant planets (Stumpf et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Astrometric planet search around southern ultracool dwarfs

Lazorenko

Ségransan

Martín

et al. 2014

A&A

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Context. Extrasolar-planet searches that target very low-mass stars and brown dwarfs are hampered by intrinsic or instrumental limitations. Time series of astrometric measurements with precisions better than one milli-arcsecond can yield new evidence on the planet occurrence around these objects. Aims. We present first results of an astrometric search for planets around 20 nearby dwarf stars with spectral types M8-L2. Methods. Over a time-span of two years, we obtained I-band images of the target fields with the FORS2 camera at the Very Large Telescope. Using background stars as references, we monitored the targets' astrometric trajectories, which allowed us to measure parallax and proper motions, set limits on the presence of planets, and to discover the orbital motions of two binary systems. Results. We determined trigonometric parallaxes with an average accuracy of 0.09 mas ( 0.2%), which resulted in a reference sample for the study of ultracool dwarfs at the M/L transition, whose members are located at distances of 9.5-40 pc. This sample contains two newly discovered tight binaries (DE0630−18 and DE0823−49) and one previously known wide binary (DE1520−44). Only one target shows I-band variability >5 mmag rms. We derived planet exclusion limits that set an upper limit of 9% on the occurrence of giant planets with masses 5 M J in intermediate-separation (0.01-0.8 AU) orbits around M8-L2 dwarfs. Conclusions. We demonstrate that astrometric observations with an accuracy of 120 µas over two years are feasible from the ground and can be used for a planet-search survey. The detection of two tight very low-mass binaries shows that our search strategy is efficient and may lead to the detection of planetary-mass companions through follow-up observations.

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“…We calculate rotational and absolute radial velocities (in a companion paper, we reported relative radial velocities for stars with multiple observations Rodler et al (2012)), and measure p-EWs of 12 neutral atomic lines.…”

Section: Introductionmentioning

confidence: 99%

Intermediate Resolution Near-Infrared Spectroscopy of 36 Late M Dwarfs

Deshpande

Martín

Montgomery

et al. 2012

The Astronomical Journal

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We present observations of 36 late-M dwarfs obtained with the KeckII/NIRSPEC in the J-band at a resolution of ∼ 20,000. We have measured projected rotational velocities, absolute radial velocities, and pseudo-equivalent widths of atomic lines. 12 of our targets did not have previous measurements in the literature.For the other 24 targets, we confirm previously reported measurements. We find that 13 stars from our sample have v sin i below our measurement threshold (12 km s −1 ) whereas four of our targets are fast rotators (v sin i > 30 km s −1 ). As fast rotation causes spectral features to be washed out, stars with low projected rotational velocities are sought for radial velocity surveys.At our intermediate spectral resolution we have confirmed theidentification of neutral atomic lines reported in McLean et al. (2007). We also calculated pseudo-equivalent widths (p-EW) of 12 atomic lines. Our results confirm that the p-EW of K I lines are strongly dependent on spectral types. We observe that the p-EW of Fe I and Mn I lines remain fairly constant with later spectral type. We suggest that those lines are particularly suitable for deriving metallicities for late-M dwarfs.

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Search for radial velocity variations in eight M-dwarfs with NIRSPEC/Keck II

Cited by 16 publications

References 31 publications

Discovery of a Very Low Mass Triple With Late-M and T Dwarf Components: Lp 704-48/SDSS J0006–0852ab

Discovery of a Very Low Mass Triple With Late-M and T Dwarf Components: Lp 704-48/SDSS J0006–0852ab

Astrometric planet search around southern ultracool dwarfs

Intermediate Resolution Near-Infrared Spectroscopy of 36 Late M Dwarfs

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