Discovery of the Young L Dwarf WISE J1741102.78-464225.5
Adam C. Schneider, Michael C. Cushing, J. Davy Kirkpatrick, Gregory N. Mace, Christopher R. Gelino, Jacqueline K. Faherty, Sergio Fajardo-Acosta, Scott S. Sheppard
aa r X i v : . [ a s t r o - ph . S R ] N ov Discovery of the Young L Dwarf WISE J174102.78 − Adam C. Schneider a , Michael C. Cushing a , J. Davy Kirkpatrick b , Gregory N. Mace b,c ,Christopher R. Gelino b,d , Jacqueline K. Faherty e , Sergio Fajardo-Acosta b , and Scott S.Sheppard f ABSTRACT
We report the discovery of the L dwarf WISE J174102.78 − J − K S = 2.35 ± ± g , age, and mass values of 1450 ±
100 K, 4.0 ± − ), 10-100 Myr, and 4-21 M Jup , respectively. With an estimated distance of 10-30pc, we explore the possibility that WISE J174102.78-464225.5 belongs to one of the youngnearby moving groups via a kinematic analysis and we find potential membership in the β Pictoris or AB Doradus associations. A trigonometric parallax measurement and a preciseradial velocity can help to secure its membership in either of these groups. a Department of Physics and Astronomy, University of Toledo, 2801 W. Bancroft St., Toledo, OH 43606,USA; [email protected] b Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA91125, USA c Department of Physics and Astronomy, UCLA, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547, USA d NASA Exoplanet Science Institute, Mail Code 100-22, California Institute of Technology, 770 SouthWilson Ave, Pasadena, CA 91125, USA e Department of Astronomy, University of Chile, Camino El Observatorio 1515, Casilla 36-D, Santiago,Chile f Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Rd. NW,Washington, DC 20015, USA
1. Introduction
The
Wide-field Infrared Survey Explorer (WISE) has heralded in an unprecedented eraof substellar discovery. WISE surveyed the entire sky at 3.4, 4.6, 12, and 22 µ m (W1, W2,W3, and W4 bands), with channels W1 and W2 designed specifically to be sensitive to coldbrown dwarfs with effective temperatures ( T eff ) less than 1400 K (Wright et al. 2010). Withthe substantial sample of substellar objects discovered by WISE (e.g. Kirkpatrick et al.2011, Mace et al. 2013, and Thompson et al. 2013), we can now perform individual in-depthstudies to probe the evolution of such objects. It is critical when investigating the evolutionof substellar objects to identify sources at various ages in order to construct a completeevolutionary sequence. The majority of L and T dwarfs discovered to date are old (age > − − − −
2. Identification and Observations2.1. Identification
WISE 1741 − W − W > >
20. In an attempt to exclude extragalactic objects, candidatesare also required to have W − W > W − W − ′′ to ensure moderate to high proper motions.Lastly, candidates are required to not be flagged as a solar system object. This search hasresulted in the detection of 55 L and T dwarfs, previously discussed in Kirkpatrick et al.(2011), Mace et al. (2013), and Thompson et al. (2013). We observed WISE 1741 − . ′′ λ /∆ λ ) of ∼
150 over the range 0.8 - 2.5 µ m.A series of 10 120s exposures were obtained at two different nod positions along the 15 ′′ longslit, which was oriented to the parallactic angle. The A0V star HD 161706 was observedat a similar airmass as WISE 1741 − WISE 1741 − λ /∆ λ ≈ µ m. Four 500s exposures were takeneach night in an ABBA dither pattern. The A0V stars HIP 84305 (V = 8.41) and HIP 89666(V = 8.65) were also observed for telluric correction purposes. We also obtained flat-fieldand arc lamp (ThAr) exposures for pixel response and wavelength calibration. Data werereduced using the FIREHOSE package, which employs modified routines from the SpeXtooldata reduction package (Vacca et al. 2003, Cushing et al. 2004).
3. Discussion3.1. Comparison to Spectral Standards
The SpeX near-infrared spectrum is presented in Figure 1, with prominent atomicand molecular lines labeled. We first attempted to determine the spectral type of WISE1741 − ). A comparison of WISE 1741 − − − ± O and FeHband strengths.We also investigated the near-infrared spectral type indices examined by Allers & Liu(2013). Most of these indices are degenerate for spectral types later than L5. Because theby-eye comparisons suggest a spectral type later than L5, only the H OD index, originallydefined by McLean et al. (2003), is useful. We calculated an H OD index of 0.78 which,utilizing the polynomial fits in Table 3 of Allers & Liu (2013), gives a spectral type of ∼ L5.5. http://pono.ucsd.edu/ ∼ adam/browndwarfs/spexprism/library.html The spectrum of WISE 1741 − − γ - Faherty et al. 2013), and the red L dwarf WISEP J004701.06+680352.1(W0047+6803; SpT (NIR) = L7.5 (pec) - Gizis et al. 2012). We derive a near-infraredspectral type of L7 (pec) for 2M0355+1133 using the method outlined in Appendix A. Allthree spectra match WISE 1741 − − − O absorption than 2M0355+1133.W0047+6803 is the best match at J, though is slightly redder than WISE 1741 − − OD spectral type index, and the comparison to other red L dwarfs, weassign a spectral type of L7 ± − The “BT-Settl” models from the Phoenix/NextGen group (Allard et al. 2011), using thesolar abundances from Asplund et al. (2009), were used to estimate the T eff and log g valuesof WISE 1741 − g values of 3.5 to 5.5 (cm s − ) in steps of 0.5 dex to our measured SpeX spectrum. In order tocompare the models to our measured spectrum, each model spectrum was resampled to beuniform in ln( λ ) space, smoothed with a Gaussian kernel to a resolving power of 150, andresampled onto the same wavelength grid as the SpeX spectrum. Following Cushing et al.(2008), a goodness of fit parameter is evaluated for each model spectrum. The goodness offit parameter is defined as G k = n X i =1 (cid:18) f i − C k F k,i σ i (cid:19) (1)where n corresponds to each data pixel, f i is the flux density of the data, F k,i is the flux 6 –density of the model k , and σ i are the errors for each observed flux density. The C k parameteris a multiplicative constant given by C k = P f i F k,i /σ i P F k,i /σ i . (2) C k is equivalent to ( R/d ) , where R is the stellar radius and d is the distance (see Section3.4.1). We performed a Monte Carlo simulation using our observed spectrum to determinethe uncertainty of the best fitting spectrum (e.g. Cushing et al. 2010). We generated 1000simulated data sets using both the absolute flux calibration uncertainty and the individualflux uncertainties at each wavelength. Each measured flux in the SpeX spectrum is randomlydrawn from a single Gaussian distribution centered on the observed flux with a width givenby the observed variance. The entire spectrum is also multiplied by a factor randomlydrawn from a Gaussian distribution centered at one with a width given by the absolute fluxcalibration uncertainty.Several low-gravity spectral models provided the best fits (Figure 4). The best fittingmodel spectrum was that with T eff = 1600 K and a log g value of 3.5. In Section 3.4.3 weshow that a T eff of 1600 K and a log g of 3.5 suggest an unphysical age of ≤ − T eff =1500 K and log g = 4.0; T eff = 1400 K and log g = 4.0) for further analysis. The three bestfitting models are displayed in Figure 4. We take T eff = 1450 ±
100 K and log g = 4.0 ± − ) as our final estimates for these parameters. This temperature is in agreement withtemperatures deduced for other ∼ L7 dwarfs (Golimowski et al. 2004).
A byproduct of the model fitting technique is an estimate of the multiplicative constant C k that is equivalent to ( R / d ) , where R is the radius of the star and d is the distancefrom Earth. Therefore, a stellar radius, in combination with model spectrum comparisons,can provide a distance estimate. We utilized four sets of low-mass evolutionary modelscombined with our best fit T eff and log g ranges to estimate a stellar radii; the “COND”models (Baraffe et al. 2003), the “DUSTY” models (Chabrier et al. 2000), and the cloudyand cloudless models of Saumon & Marley (2008). For the “DUSTY” models, dust grains aresuspended, while in the “COND” models dust is removed from the photosphere. Similarly,the cloudy and cloudless models of Saumon & Marley (2008) account for cloud sedimenta- 7 –tion, where the sedimentation efficiency parameter ( f sed ) = 2 for the cloudy models and thecloudless models include no opacity from clouds. We found a radius range of 0.137-0.161R ⊙ (1.36-1.60 R Jup ) for the “DUSTY” and “COND” models, and a range of 0.1398-0.1752R ⊙ (1.39-1.74 R Jup ) for the Saumon & Marley (2008) models. This range, in combinationwith the C k values determined via model fitting result in a so-called “spectroscopic parallax”(Bowler et al. 2009) of 8-11 pc.We also estimate photometric distances using the relations of Looper et al. (2008a),Kirkpatrick et al. (2011), and Dupuy & Liu (2012). For a spectral type range of L5-L9 andthe 2MASS and WISE magnitudes given in Table 1, we calculate distance ranges of 12-25 pcand 11-28 pc for the Looper et al. (2008a) and Dupuy & Liu (2012) relations, respectively.For the WISE W2 relation of Kirkpatrick et al. (2011), we calculated a distance range of11-14 pc. The distance estimates using the K S , W1, and W2 magnitudes provided theclosest matches to the distance derived via spectroscopic parallax (11-20 pc, 11-17 pc, and10-15 pc for K S , W1, and W2, respectively), which could imply that the magnitudes fromthe wavelength region between K S and WISE W2 is the least affected by youth. Thisis further supported by Figure 9 of Faherty et al. (2013), which shows that the absoluteflux of 2M0355+1133 matches the field L5 2M1507-16 well at K, while it is underluminouseverywhere blueward of ∼ µ m. Liu et al. (2013) also find that many of their young mid-Ldwarfs with measured parallaxes are fainter at J than field objects of comparable spectraltype. This is supported by the results of Faherty et al. (2012), in which they find that ∼ − The near-infrared spectrum of WISE 1741 − µ m, most notably H O, which results in apeaked triangular appearance.WISE 1741 − J − K S color ( J − K S = 2.35 ± W − W W − W ± J − K S and W − W J − K S and W − W − <
100 Myr.Following the example of Cruz et al. (2009), we take 10 Myr as a lower age limit becauseWISE 1741 − µ m bandheads), VO absorp-tion (centered on the 1.06 µ m bandhead), the K I line at 1.14 µ m, and the H-band continuumshape. We note here that the alkali and molecular band indices are most useful for spectraltypes between ∼ M9 and L5, and are degenerate for our predicted spectral type of L7. Wecan, however, determine the H -cont index, which is designed to quantify the H-band contin-uum shape. We calculated an H -cont value of 0.955 for our SpeX spectrum, which followsthe low gravity sequence, well separated from the location of normal field dwarfs (see Figure24 of Allers & Liu 2013). For the similarly red L7.5 (pec) dwarf W0047+6803, we calculatean H -cont value of 0.963. We can also utilize the K I pseudo-equivalent width (EW) def-initions of Allers & Liu (2013) using our moderate-resolution FIRE spectrum. Alkali linesare known to be gravity sensitive, and can appear narrower than those seen in normal fielddwarfs because of the lack of pressure broadened wings (Kirkpatrick et al. 2006). We firstsmoothed our FIRE spectrum with a gaussian kernel to a resolution (R ∼ µ m K I lines of 0.93, 1.89, and 0.86 ˚A, respectively. We similarly measure thepseudo-EWs of W0047+6803 (3.31, 2.62, and 1.16 ˚A) and W0355+1133 (2.58, 2.59, and 0.98˚A). All three measured pseudo-EWs are consistent with a low-gravity object (see Figure 23and Table 10 of Allers & Liu 2013). Figures 6 and 7 display the K I spectral line regionsof WISE 1741 − − −
16 and the L7 field dwarf DENIS 0205 − − ≤
10 Myr) brown dwarfs from an older field population, and can be used with confidenceeven with low resolution spectra. We note that the sample used in Canty et al. (2013) has adearth of objects with intermediate ages ( >
10 Myr and less than the age of field dwarfs) andthe effectiveness of the H ( K ) index in this age range is not well constrained. They definean H ( K ) index to quantify the K-band continuum slope, given as H ( K ) = F λ (2 . µm ) F λ (2 . µm ) (3)where F λ (2 . µm ) and F λ (2 . µm ) are the median fluxes over a total range of 0.02 µ m cen-tered at 2.17 and 2.24 µ m, respectively. We calculated the H ( K ) index of WISE 1741 − ≤ L0. Toextend the work of Canty et al. (2013) into the L dwarf regime, we gathered all availablespectra from the Spex Prism Spectral Library for which a resolving power ≥
120 is available.Since many of the given or published spectral types were not determined homogeneously, weindependently derived near-infrared spectral types for each available spectrum based on theKirkpatrick et al. (2010) L dwarf classification scheme (See Appendix A). The H ( K ) indexof each L dwarf was calculated, and is shown in Figure 10 and given in Table 2. Any spectrumfound to be especially noisy was not included in this analysis. While a spectral type depen-dance is seen past L0 (the H ( K ) index generally increases with increasing spectral type),WISE 1741-44642 and the red L dwarfs 2M0355+1133 and 2M0047+6803 are seen to deviatefrom the field population. Also showing strong deviations below their near-infrared spectraltypes are the young, red L6 dwarf 2MASS J214816.28+400359.3 (Looper et al. 2008b), theyoung, red L2 dwarf 2MASS J014158.23-463357.4 (Kirkpatrick et al. 2006), the low gravityL dwarf 2MASS J224953.45+004404.6 (SpT opt = L4 γ ; Faherty et al. 2013), and the red L8dwarf SDSSp J010752.33+004156.1 (Geballe et al. 2002).In summary, WISE 1741 − H ( K ) index, that are characteristic of a young 10 –age. We compared the position of WISE 1741 − T eff vs. log g space with the “COND”(Baraffe et al. 2003), “DUSTY” (Chabrier et al. 2000), and Saumon & Marley (2008) cloudyand cloudless low-mass evolutionary models (discussed in Section 3.4.1). We note herethat the spectral models of Allard et al. (2011) and the low-mass evolutionary models usedin Section 3.4 are not self-consistent. However, such a comparison is the only availableprocedure for determining the physical characteristics of WISE 1741 − T eff = 1600, log g = 3.5) suggests an age ≤ − T eff =1450 ±
100 K and log g = 4.0 ± − − − − Jup , whilethe Saumon & Marley (2008) models suggest a mass range of 4-15 M
Jup (Figures 11 and 12).We take 4-21 M
Jup as our final mass estimate. − Because WISE 1741 − − − space motions for WISE 1741 − − − − − − − β Pictoris and AB Doradusassociations are 94.2 and 91.9%, respectively. Furthermore, the convergent point analysistool returns the ideal kinematic distances and radial velocities for membership in each group.The kinematic distance is predicted to be 12.3 pc for β Pictoris and 19.1 pc for AB Doradus,distances that match well with our photometric distance estimates. The predicted radialvelocities are -5.4 km s − and 2.1 km s − for β Pictoris and AB Doradus, respectively.The Bayesian Analysis for Nearby Young AssociatioNs tool (or BANYAN; Malo et al.2013) uses Bayesian inference to determine association membership probabilities, predictedradial velocities, and the most probable distances for several young nearby associations.Unlike the convergent point analysis tool of Rodriguez et al. (2013), the BANYAN tooldetermines membership probabilities so that they sum to 100%. Using the WISE All-sky UVW space motions are calculated using the measured radial velocity.
U V W are defined with respectto the Sun. U is positive toward the Galactic center, V is positive in the direction of Galactic rotation, andW is positive toward the north Galactic pole.
12 –catalog position and the proper motions provided in Table 1, the BANYAN tool determinedthat WISE 1741 − β Pictoris, AB Doradus, Argus, and old field stars are40.75%, 43.45%, 15.34%, and 0.47%, respectively (Argus is not considered by the convergentpoint analysis tool of Rodriguez et al. 2013). As with the convergent point analysis tool, theBANYAN tool claims a high likelihood that WISE 1741 − β Pictoris orAB Doradus ( ∼
84% total). Statistical distances are in excellent agreement with those fromthe convergent point method as well; 13.0 pc for β Pictoris and 19.5 pc for AB Doradus, againconsistent with our photometric distance estimates. The predicted radial velocities fromBANYAN are -4.7 km s − and +2.57 km s − for β Pictoris and AB Doradus, respectively.We estimated the radial velocity of WISE 1741 − µ m and from these calculated a radial velocity, corrected forthe heliocentric radial velocity, of -5.7 ± − . While uncertainties using this methodare large, a radial velocitiy significantly discrepant from those predicted for WISE 1741 − β Pictoris or AB Doradus member could have ruled out potential membership. Ourmeasured radial velocity range does not rule out β Pictoris or AB Doradus membership. Wealso examined the XYZ position of WISE 1741 − β Pictoris (9.27 ± ± ± ± ± ± − β Pictoris and AB Doradus associations.Given the youthful characteristics of the near-infrared spectrum of WISE 1741 − β Pictoris and AB Doradus associations, webelieve there is a strong possibility of moving group membership. The position and propermotion of WISE 1741 − β Pictoris and AB Dordadosmembers from Schneider (2013) is displayed in Figure 14. Accurate parallax and radialvelocity measurements will aid in clearing up any young association membership ambiguity.
4. Conclusions
We have shown through an analysis of the near-infrared spectrum and photometric colorsof WISE 1741 − − ± ±
100 K and a log g of 4.0 ± T eff and log g estimates, we estimate the mass of WISE 1741 − Jup . We also explored the possibility that WISE 1741 − − β Pictoris or AB Doradus moving groups is a possibility deservingfollow-up observations. Future parallax and radial velocity measurements can confirm anyassociation membership.This research has made use of the SIMBAD database and VizieR catalog access tool,operated at CDS, Strasbourg, France. This publication makes use of data products from theTwo Micron All Sky Survey, which is a joint project of the University of Massachusetts andthe Infrared Processing and Analysis Center/California Institute of Technology, funded bythe National Aeronautics and Space Administration and the National Science Foundation,and the
Wide-field Infrared Survey Explorer , which is a joint project of the University of Cal-ifornia, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology,funded by the National Aeronautics and Space Administration. This research has made useof the NASA/ IPAC Infrared Science Archive, which is operated by the Jet Propulsion Labo-ratory, California Institute of Technology, under contract with the National Aeronautics andSpace Administration. This research has benefitted from the SpeX Prism Spectral Libraries,maintained by Adam Burgasser at http://pono.ucsd.edu/ ∼ adam/browndwarfs/spexprism.This research has benefitted from the M, L, T, and Y dwarf compendium housed at dwar-farchives.org. Visiting Astronomer at the Infrared Telescope Facility, which is operatedby the University of Hawaii under Cooperative Agreement no. NNX − REFERENCES
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A. SpeX Near-Infrared Spectral Fitting
The SpeX Prism Spectral Library is an invaluable resource to the brown dwarf commu-nity. We chose to utilize this resource to extend the work of Canty et al. (2013) regardingthe H K youth index to the entire L dwarf spectral sequence. Since many of the given orpublished spectral types in the Spex Prism Spectral Library were not determined homoge-neously, we independently derived near-infrared spectral types for each available spectrumbased on the Kirkpatrick et al. (2010) L dwarf classification scheme. For each spectrum, wefirst normalized to 1.28 µ m, then performed a χ fitting to the region between 0.9 and 1.4 µ m. Each spectrum was then inspected by-eye over the entire near-infrared range from 0.8 to2.5 µ m to see which subtype was most similar to the spectrum in question, with the resultsof the χ fitting used as a guide. The newly derived near-infrared spectral types are givenin Table 2, along with the reference where the original near-infrared SpeX spectrum waspublished. We also include previously derived optical and near infrared spectral types, whenavailable. Those spectra with blue or red near-infrared colors compared to their best fittingspectral type are labeled as blue or red in the notes section of Table 2. The newly derived in-frared spectral types of the sample agree to within ± ∼
89% (101/114)with previously published infrared spectral types and ∼
93% (103/111) with optical spectraltypes. A comparison of the newly derived spectral types with previously published spectraltypes is shown in Figure 15.
This preprint was prepared with the AAS L A TEX macros v5.2.
18 –Table 1. WISE 1741 − α (J2000) 17:41:02.79 1 δ (J2000) − µ α cos δ (mas yr − ) − ± µ δ (mas yr − ) − ± v rad -5.7 ± −
3J (mag) 15.786 ± ± S (mag) 13.438 ± ± ± ± < J − H (mag) 1.25 ± J − K S (mag) 2.35 ± J − W ± W − W ± ± T eff ±
100 K 3log g ± − ) 3Mass 4-21 M Jup opt (Pub.) SpT
NIR (Pub.) SpT IR (Adopted) H ( K ) Ref. note2M0004 − − − − − − − − γ L0 (pec) L2 - 22 red2M0144 − − − − − − − − − opt (Pub.) SpT NIR (Pub.) SpT IR (Adopted) H ( K ) Ref. note2M0300 − − − − − γ L1 (pec) L2 - 2 red?2M0439 − − − − − − − opt (Pub.) SpT NIR (Pub.) SpT IR (Adopted) H ( K ) Ref. note2M0859 − − − − − − − − − opt (Pub.) SpT NIR (Pub.) SpT IR (Adopted) H ( K ) Ref. note2M1239+5515 L5 - L5 1.048 32M1247 − − − − − − − opt (Pub.) SpT NIR (Pub.) SpT IR (Adopted) H ( K ) Ref. note2M1617+4019 - L4 L6.5 1.064 5 sl. red2M1622+1159 - L6 L4.5 - 52M1630+4344 - L7 L8.5 1.105 32M1632+1904 L8 L8 L8 1.078 152M1633 − − − − − − − − − − − opt (Pub.) SpT NIR (Pub.) SpT IR (Adopted) H ( K ) Ref. note2M2101+1756 L7.5 - L7.5 1.097 32M2104 − − − − − − − − − λ (µm) N o r m a l i ze d F λ FeH NaK KH OFeH H O H O CO
Fig. 1.— The SpeX near-infrared spectrum of WISE 1741 − λ (µm) F λ + c o n s t a n t L4L5L6L7L8L9T0W1741−4642
Fig. 2.— The near-infrared spectrum of WISE 1741 − µ m. The spectra are separatedalong the vertical axis by a constant of 1.0 for clarity. The spectral standards used for thiscomparison are as follows: 2MASS J21580457-1550098 (L4; Kirkpatrick et al. 2010), SDSSJ083506.16+195304.4 (L5; Chiu et al. 2006), 2MASSI J1010148 − − λ (µm) F λ + c o n s t a n t W0047 +68032M2244 +20432M0355 +1133W1741−4642
Fig. 3.— The near-infrared spectrum of WISE 1741 − IR = L7.5 (pec) - Gizis et al. 2012), 2M2244+2043(SpT IR = L7.5 (pec) - Kirkpatrick et al. 2008), and 2M0355+1133 (SpT opt = L5 γ -Faherty et al. 2013). Each spectrum is normalized by the mean flux from 1.27 to 1.32 µ m.While the spectra match better than the spectral standards in Figure 2, WISE 1741 − λ (µm) F λ + c o n s t a n t ( − W m − ) k Fig. 4.—
Top:
The near-infrared spectrum of WISE 1741 − T eff and log g values. Bottom:
The distribution of G k values for the three best fitting models.Red: T eff = 1400 K and log g = 4.0, blue: T eff = 1500 K and log g = 4.0, and cyan: T eff =1600 K and log g = 3.5. 30 – J−K S (mag) −0.20.00.20.40.60.81.01.21.4 W − W ( m a g ) Fig. 5.— 2MASS J − K S vs. WISE W1 − W2 colors for dwarfs with photometric uncertainties ≤ − γ dwarfs from Table 3 of Faherty et al. (2013), the majority of whichhave optical spectral types earlier than L5. 31 – F λ + c o n s t a n t λ (µm) F λ + c o n s t a n t Fig. 6.— A K I line comparison of the WISE 1741 − F λ + c o n s t a n t λ (µm) F λ + c o n s t a n t Fig. 7.— A K I line comparison of the WISE 1741 − γ dwarf 2M0355+1133 (red) (Faherty et al. 2013). The FIRE spectrum was smoothedwith a gaussian kernel to the resolution of the comparison spectrum. The flux of bothspectra were normalized to the continuum. 32 – F λ + c o n s t a n t λ (µm) F λ + c o n s t a n t Fig. 8.— A K I line comparison of the WISE 1741 − −
16 spectrum from the BDSS (red) (McLean et al. 2007). The NIRSPECspectrum was smoothed with a gaussian kernel to the resolution of the FIRE spectrum. Theflux of both spectra were normalized to the continuum. F λ + c o n s t a n t λ (µm) F λ + c o n s t a n t Fig. 9.— A K I line comparison of the WISE 1741 − −
11 spectrum from the BDSS (red) (McLean et al. 2007). The NIRSPECspectrum was smoothed with a gaussian kernel to the resolution of the FIRE spectrum. Theflux of both spectra were normalized to the continuum. 33 –Fig. 10.— H ( K ) index as a function of spectral type for L dwarfs from the SpeX PrismSpectral Library based on our new spectral typing system. Red points indicate the mean H ( K ) index and standard deviation for L dwarfs binned by 0.5 subtype. The young and/orred L dwarfs 2M2148+4003, 2M0355+1133, 2M0141 − − − Top:
Theoretical “COND” log g vs. T eff evolutionary tracks from Baraffe et al.(2003). 1, 5, 10, 50, 100, and 120 Myr isochrones are shown by solid lines from right to left.Curves of constant mass from 0.005, 0.010, and 0.020 M ⊙ (5, 10, and 21 M Jup ) are shown bydashed lines from left to right. The red, blue, and cyan shaded regions represent the threebest model spectrum fits; T eff = 1400 K and log g = 4.0 (red), T eff = 1500 K and log g = 4.0(blue), T eff = 1600 K and log g = 3.5 (cyan). The colors match those in Figure 6. Bottom:
Same figure as on the
Left for the theoretical “DUSTY” log g vs. T eff evolutionary tracksfrom Chabrier et al. (2000). 35 –Fig. 12.— Top:
Theoretical (cloudless) log g vs. T eff evolutionary tracks fromSaumon & Marley (2008). 3, 6, 10, 20, 30, 60, 100, and 200 Myr isochrones are shownby solid lines from right to left. Curves of constant mass from 0.004 − ⊙ (4 −
17 M
Jup )in steps of 0.002 M ⊙ are shown by dashed lines from left to right. The red, blue, and cyanshaded regions represent the three best model spectrum fits; T eff = 1400 K and log g = 4.0(red), T eff = 1500 K and log g = 4.0 (blue), T eff = 1600 K and log g = 3.5 (cyan). The colorsmatch those in Figure 6. Right:
Same figure as on the
Bottom for the theoretical (cloudy -f sed = 2) log g vs. T eff evolutionary tracks from Saumon & Marley (2008). 36 –
100 80 60 40 20 0 20 40 60 80U (km/s)60402002040 V ( k m / s )
10 pc20 pc30 pc
100 80 60 40 20 0 20 40 60 80U (km/s)40302010010203040 W ( k m / s )
10 pc20 pc30 pc
Fig. 13.— UVW space velocities for WISE 1741 − − in 10 km s − steps) for distances of 10, 20, and 30 pc. Negative radial velocityvalues are represented by open circles. The black square indicates the “good box” fromZuckerman & Song (2004). The blue and green empty boxes indicate the extent of highlyprobably members from Torres et al. (2008) for β Pictoris and the AB Dor association,respectively. Small blue and green filled squares represent the core UVW values of β Pictorisand AB Doradus as defined in Faherty et al. (2013). 37 –Fig. 14.—
Left:
The positions and proper motion of WISE 1741 − Right:
The positions and proper motion of WISE 1741 − Left: