scholarly journals Individual dynamical masses of DENIS J063001.4−184014AB reveal a likely young brown dwarf triple

2020 ◽  
Vol 500 (4) ◽  
pp. 5453-5461
Author(s):  
J Sahlmann ◽  
T J Dupuy ◽  
A J Burgasser ◽  
J C Filippazzo ◽  
E L Martín ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Absolute Magnitude ◽  
Brown Dwarf ◽  
Trigonometric Parallax ◽  
Significant Difference ◽  
Relative Separation ◽  
The Individual ◽  
Available Information ◽  
Dynamical Masses

ABSTRACT The binary nature of the M8.5 dwarf DENIS J063001.4−184014AB (DE0630−18) was discovered with astrometric monitoring from the ground, which determined the unresolved photocentric orbit and the trigonometric parallax of the system. Here we present radial velocity monitoring and resolved observations in the near-infrared with Keck aperture masking that allows us to measure the system’s relative separation and brightness. By combining all available information, we determine the individual dynamical masses of the binary components to be $M_1 = 0.052^{+0.009}_{-0.008}$MSun and $M_2 = 0.052^{+0.005}_{-0.004}$MSun, both firmly in the substellar regime. These masses are surprising, given the object’s M8.5 optical spectral type and equivalent absolute magnitude, and the significant difference in brightness between the components (ΔK = 1.74 ± 0.06 mag). Our results suggest that DE0630−18 is a relatively young system (∼200 Myr) with a secondary component that is itself a potentially unresolved binary.

scholarly journals A possible dividing line between massive planets and brown-dwarf companions

2010 ◽  
Vol 6 (S276) ◽  
pp. 117-120 ◽  
Author(s):  
Johannes Sahlmann ◽  
Damien Ségransan ◽  
Didier Queloz ◽  
Stéphane Udry
Keyword(s):  
Radial Velocity ◽  
Formation Process ◽  
Brown Dwarfs ◽  
Mass Range ◽  
Velocity Measurements ◽  
Brown Dwarf ◽  
The One ◽  
The Individual ◽  
Dividing Line

AbstractBrown dwarfs are intermediate objects between planets and stars. The lower end of the brown-dwarf mass range overlaps with the one of massive planets and therefore the distinction between planets and brown-dwarf companions may require to trace the individual formation process. We present results on new potential brown-dwarf companions of Sun-like stars, which were discovered using CORALIE radial-velocity measurements. By combining the spectroscopic orbits and Hipparcos astrometric measurements, we have determined the orbit inclinations and therefore the companion masses for many of these systems. This has revealed a mass range between 25 and 45 Jupiter masses almost void of objects, suggesting a possible dividing line between massive planets and sub-stellar companions.

scholarly journals T Tauri Binaries in Orion: Evidence for Accelerated and Synchronized Disk Evolution

2011 ◽  
Vol 7 (S282) ◽  
pp. 452-453 ◽  
Author(s):  
Sebastian Daemgen ◽  
Monika G. Petr-Gotzens ◽  
Serge Correia
Keyword(s):  
Accretion Disks ◽  
Near Infrared ◽  
Orion Nebula ◽  
Spatially Resolved ◽  
T Tauri ◽  
Significant Difference ◽  
Disk Evolution ◽  
The Individual ◽  
Gas Accretion

AbstractIn order to trace the role of binarity for disk evolution and hence planet formation, we started the currently largest spatially resolved near-infrared photometric and spectroscopic study of the inner dust and accretion disks of the individual components of 27 visual, 100–400 AU binaries in the Orion Nebula Cluster (ONC). We study the frequency of Brackett-γ (2.165μm) emitters to assess the frequency of accretion disk-bearing stars among the binaries of the ONC: only 34±9% of the binary components show signs of accretion and, hence, the presence of gaseous inner disks—less than the fraction of gas accretion disks among single stars of the ONC of ~50%. Additionally, we find a significant difference between binaries above and below 200 AU separation: no close systems with only one accreting component are found. The results suggest shortened disk lifetimes as well as synchronized disk evolution.

scholarly journals Near-Infrared Adaptive Optics Spectroscopy of Binary Brown Dwarfs HD 130948B and HD 130948C

2003 ◽  
Vol 211 ◽  
pp. 269-270
Author(s):  
M Goto ◽  
A.T. Tokunaga ◽  
M. Cushing ◽  
D. Potter ◽  
N. Kobayashi ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Binary System ◽  
Adaptive Optics ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Brown Dwarfs ◽  
Brown Dwarf ◽  
Low Mass ◽  
The Individual

We present near-infrared spectroscopy of low-mass companions in the HD 130948 system (Goto et al. 2002a). Adaptive optics on the Subaru Telescope allowed for spectroscopy of the individual components of the 0″.13 binary system. Based on a direct comparison with a series of template spectra, we determined the spectral types of HD 130948B and C to be L4 ± 1. We find they are most likely a binary brown dwarf system.

scholarly journals Direct Imaging Of Long Period Radial Velocity Targets With NICI

2013 ◽  
Vol 8 (S299) ◽  
pp. 66-67
Author(s):  
Graeme S. Salter ◽  
Chris G. Tinney ◽  
Robert A. Wittenmyer ◽  
James S. Jenkins ◽  
Hugh R.A. Jones ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Minimum Mass ◽  
Post Processing ◽  
Velocity Measurements ◽  
Brown Dwarf ◽  
Direct Imaging ◽  
Parameter Spaces ◽  
Long Period ◽  
Imaging Parameter

AbstractWe are finally entering an era where radial velocity and direct imaging parameter spaces are starting to overlap. Radial velocity measurements provide us with a minimum mass for an orbiting companion (the mass as a function of the inclination of the system). By following up these long period radial velocity detections with direct imaging we can determine whether a trend seen is due to an orbiting planet at low inclination or an orbiting brown dwarf at high inclination. In the event of a non-detection we are still able to put a limit on the maximum mass of the orbiting body. The Anglo-Australian Planet Search is one of the longest baseline radial velocity planet searches in existence, amongst its targets are many that show long period trends in the data. Here we present our direct imaging survey of these objects with our results to date. ADI Observations have been made using NICI (Near Infrared Coronagraphic Imager) on Gemini South and analysed using an in house, LOCI-like, post processing.

scholarly journals The Luminosity Calibration of the HR Diagram

1998 ◽  
Vol 11 (1) ◽  
pp. 558-558
Author(s):  
A.E. Gómez ◽  
X. Luri ◽  
M.O. Mennessier ◽  
J. Torra ◽  
F. Figueras ◽  
...  
Keyword(s):  
Likelihood Estimation ◽  
Absolute Magnitude ◽  
Motion Data ◽  
Final Sample ◽  
Peculiar Stars ◽  
Absolute Magnitudes ◽  
The Individual ◽  
Available Information ◽  
Hipparcos Parallax ◽  
Hr Diagram

An extensive work on the luminosity calibration of the HR diagram has been performed using the LM method based on the Maximum Likelihood estimation (Luri et al. 1996). The method uses all available information: Hipparcos parallax and proper motion data as well as radial velocities and some measured spectroscopic or photometric parameters related to luminosity. On the other hand, the method takes into account the censorship of the sample and the errors of the data. Finally, it is able to identify and separate in a given sample, groups with different luminosity, kinematical or spatial characteristics providing not only the corresponding luminosity calibration relationship, but also improved individual absolute magnitude estimates. In order to asses how reliable the luminosity calibrations based on the MK spectral classification are, the LM method has been applied to a sample of B to K stars with MK classification selected from the Hipparcos survey. All known binaries, variables and spectroscopically peculiar stars were removed from the sample. The final sample contains 22054 stars. Our results show that the relation between absolute magnitude and luminosity class has a large intrinsic dispersion. As a consequence, the assignation to a star of a mean absolute magnitude given by a MK classification calibration is a rough procedure. It is preferable to use the individual absolute magnitudes estimated using all the available information for each star, like the estimates provided by the LM method (Gómez et al. 1997).

The influence of artificial light on the capture of deep-water demersal fish by bottom trawling

2002 ◽  
Vol 82 (2) ◽  
pp. 339-344 ◽  
Author(s):  
J.D.M. Gordon ◽  
O.A. Bergstad ◽  
P.L. Pascoe
Keyword(s):  
Demersal Fish ◽  
Individual Species ◽  
North East ◽  
Numerical Abundance ◽  
Significant Difference ◽  
Fish Catch ◽  
Total Fish ◽  
Components Analysis ◽  
The Individual ◽  
Available Information

Lights were attached to the headline of a bottom trawl during a series of tows at 1000 m depth in the Rockall Trough (north-east Atlantic). There was no significant difference in the overall numerical abundance of demersal fish between the trawl catches with light and the controls with no light. A principal components analysis based on the total fish catch between the experimental and the control stations showed no segregation. At the individual species level significant differences in catch rate were found for eight species. These are discussed in relation to the small amount of available information on the visual systems of deep-sea demersal fish and their diet.

scholarly journals Young Binaries as a Test for Pre-Main Sequence Evolutionary Tracks

2006 ◽  
Vol 2 (S240) ◽  
pp. 369-376
Author(s):  
Hans Zinnecker
Keyword(s):  
Main Sequence ◽  
Absolute Magnitude ◽  
Star Formation History ◽  
High Angular Resolution ◽  
Bolometric Luminosity ◽  
Long Baseline ◽  
Low Mass ◽  
The Individual ◽  
Stellar Masses ◽  
Dynamical Masses

AbstractObservations of young low-mass binaries (t ≲ 107 yr, M ≲ 3 M_⊙) can be used to calibrate pre-Main Sequence (pre-MS) evolutionary tracks. Recent high angular resolution HST/FGS, speckle, and long-baseline interferometry have resolved the astrometric orbits of a few SB2 pre-MS binaries and have provided the individual dynamical masses of their components as well as the system orbital parallaxes. Spectroscopic fits and filter photometry have permitted to determine SpT (temperatures) and a good estimate of the absolute magnitude (bolometric luminosity) of the components, which in turn allows one to place the components on a theoretical HR-diagram. In this way, one can check (a) whether the measured dynamical masses agree with the predicted masses on the tracks and (b) whether both components lie on an isochrone, as they should for a coeval physical pair of stars.With a sufficiently large sample of different masses and ages of resolved SB2 systems, most of the parameter space of pre-MS tracks can be tested, even for very low stellar masses (M < 0.5 M_⊙) and very young ages (< 2 Myr). This is a prerequisite in order to derive the IMF and star formation history in very young clusters and associations.

scholarly journals HR 10: a main-sequence binary with circumstellar envelopes around both components

2019 ◽  
Vol 629 ◽  
pp. A19 ◽  
Author(s):  
B. Montesinos ◽  
C. Eiroa ◽  
J. Lillo-Box ◽  
I. Rebollido ◽  
A. A. Djupvik ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Main Sequence ◽  
Near Infrared ◽  
Theoretical Modelling ◽  
Evolutionary Status ◽  
Circumstellar Material ◽  
Combined Use ◽  
Individual Star ◽  
The Individual ◽  
Absorption Features

Context. This paper is framed within a large project devoted to studying the presence of circumstellar material around main sequence stars, and looking for exocometary events. The work concentrates on HR 10 (A2 IV/V), known for its conspicuous variability in the circumstellar narrow absorption features of Ca II K and other lines, so far interpreted as β Pic-like phenomena, within the falling evaporating body scenario. Aims. The main goal of this paper is to carry out a thorough study of HR 10 to find the origin of the observed variability, determine the nature of the star, its absolute parameters, and evolutionary status. Methods. Interferometric near-infrared (NIR) observations, multi-epoch high-resolution optical spectra spanning a time baseline of more than 32 yr, and optical and NIR photometry, together with theoretical modelling, were used to tackle the above objectives. Results. Our results reveal that HR 10 is a binary. The narrow circumstellar absorption features superimposed on the photospheric Ca II K lines – and lines of other species – can be decomposed into two or more components, the two deep ones tracing the radial velocity of the individual stars, which implies that their origin cannot be ascribed to transient exocometary events, their variability being fully explained by the binarity of the object. There does not appear to be transient events associated with potential exocomets. Each individual star holds its own circumstellar shell and there are no traces of a circumbinary envelope. Finally, the combined use of the interferometric and radial velocity data leads to a complete spectrometric and orbital solution for the binary, the main parameters being: an orbital period of 747.6 days, eccentricities of the orbits around the centre of mass 0.25 (HR 10-A), 0.21 (HR 10-B) and a mass ratio of q = MB∕MA = 0.72–0.84. The stars are slightly off the main sequence, the binary being ~530 Myr old.

Writing in Aphasia Rehabilitation: Cursive vs Manuscript

1976 ◽  
Vol 41 (4) ◽  
pp. 523-529 ◽  
Author(s):  
Daniel R. Boone ◽  
Harold M. Friedman
Keyword(s):  
Correct Response ◽  
The Other ◽  
Read Aloud ◽  
Writing Style ◽  
Reading And Writing ◽  
Manual Responses ◽  
Significant Difference ◽  
Written Form ◽  
The Individual ◽  
Read Number

Reading and writing performance was observed in 30 adult aphasic patients to determine whether there was a significant difference when stimuli and manual responses were varied in the written form: cursive versus manuscript. Patients were asked to read aloud 10 words written cursively and 10 words written in manuscript form. They were then asked to write on dictation 10 word responses using cursive writing and 10 words using manuscript writing. Number of words correctly read, number of words correctly written, and number of letters correctly written in the proper sequence were tallied for both cursive and manuscript writing tasks for each patient. Results indicated no significant difference in correct response between cursive and manuscript writing style for these aphasic patients as a group; however, it was noted that individual patients varied widely in their success using one writing form over the other. It appeared that since neither writing form showed better facilitation of performance, the writing style used should be determined according to the individual patient’s own preference and best performance.

Aftermath Effect Of GST On Consumer Purchasing Power

2019 ◽  
Vol 118 (5) ◽  
pp. 122-131
Author(s):  
S. Thowseaf ◽  
M. Ayisha Millath ◽  
K. Malik Ali
Keyword(s):  
Living Standard ◽  
Purchasing Power ◽  
Percentage Increase ◽  
Defense System ◽  
Key Factors ◽  
Predominant Role ◽  
Tax System ◽  
Significant Difference ◽  
The Individual ◽  
Taxation System

Tax is an important source of income for the country. It is through tax; country strengthens its defense system, infrastructure, and government. Hence, tax system plays a predominant role in developing country’s economy. The complication in taxation system and liberty for taxpayers are key factors generating loopholes for corruption. GST is superior taxation system over VAT but, if neither properly implemented nor scrutinized according to the economy, it is people residing get affected.  GST taxation system is capable of increasing legal transaction, reducing corruption and complexity that exists in current taxation. India is 166th country to adopt GST and GST taxation slab in India is 0%, 5%, 12%, 18% and 28%.  Although average Tax levied is 14.8750% in India, it is 28% tax that is levied for most of the commodities, which are directly or indirectly used in everyday life of common individuals. Despite, GST being favorable to distributor in-terms of profit and government to attain tax by increasing legal transaction through invoice. It is noted that for the same percentage of taxation, the amount does not vary for VAT and GST. The tax slab decreased for 71 commodities and no change in 21 commodities; there has been an increase in tax slab for 60 commodities. 26% taxation was levied for most commodities considered was currently levied by 28% taxation which is greater than before. It was found that average tax percentage reduced was calculated to be 6.07143. The average tax percentage increase was calculated to be 4.7833 percentage for the considered commodities. The overall tax average tax percentage is estimated to be 14.8750% which does not have a significant difference concerning tax levied before GST, which was calculated to be 15.7829% for considered commodities. Therefore, the consumer purchasing power and overall living standard of the individual in India will remain almost same.

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