THE EXTREMELY RED, YOUNG L DWARF PSO J318.5338−22.8603: A FREE-FLOATING PLANETARY-MASS ANALOG TO DIRECTLY IMAGED YOUNG GAS-GIANT PLANETS

By Michael C. Liu, E. Magnier, N. Deacon, K. Allers, T. Dupuy, Michael C. Kotson, K. Aller, W. Burgett, K. Chambers, P. Draper and 9 more. 2013

181 citations recorded by the source corpus.

We have discovered using Pan-STARRS1 an extremely red late-L dwarf, which has (J − K)MKO = 2.78 and (J − K)2MASS = 2.84, making it the reddest known field dwarf and second only to 2MASS J1207−39b among substellar companions. Near-IR spectroscopy shows a spectral type of L7 ± 1 and reveals a triangular H-band continuum and weak alkali (K i and Na i) lines, hallmarks of low surface gravity. Near-IR astrometry from the Hawaii Infrared Parallax Program gives a distance of 24.6 ± 1.4 pc and indicates a much fainter J-band absolute magnitude than field L dwarfs. The position and kinematics of PSO J318.5−22 point to membership in the β Pic moving group. Evolutionary models give a temperature of 1160 K and a mass of 6.5 MJup, making PSO J318.5−22 one of the lowest mass free-floating objects in the solar neighborhood. This object adds to the growing list of low-gravity field L dwarfs and is the first to be strongly deficient in methane relative to its estimated temperature. Comparing their spectra suggests that young L dwarfs with similar ages and temperatures can have different spectral signatures of youth. For the two objects with well constrained ages (PSO J318.5−22 and 2MASS J0355+11), we find their temperatures are ≈400 K cooler than field objects of similar spectral type but their luminosities are similar, i.e., these young L dwarfs are very red and unusually cool but not “underluminous.” Altogether, PSO J318.5−22 is the first free-floating object with the colors, magnitudes, spectrum, luminosity, and mass that overlap the young dusty planets around HR 8799 and 2MASS J1207−39.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/0ba030d240246c7c54c44d75f9d7791fe6af9117

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In Astronomy and Astrophysics

1. Michael C. Liu
2. T. Dupuy
3. B. Bowler
4. A. Burgasser
5. K. Allers
6. Kelle Cruz
7. K. Luhman
8. J. D. Kirkpatrick

Citations in the corpus

• Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e (2020, background): “Here one approach could be to obtain mid-IR spectra of HR 8799 planet analogs such as PSO J318 (Liu et al. 2013)14.”
• Individual Dynamical Masses of Ultracool Dwarfs (2017, background): “…association of NLTT 20346 to the 2MASS J0850+1057 system is questionable (see Section 6.4 of Dupuy & Liu 2012), and the discovery and characterization of young late-L dwarfs indicates that they tend to be fainter at J-band, not brighter (Faherty et al. 2012; Liu et al. 2013a; Liu et al. 2016).”
• THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS (2016, methodology): “The notable outlier is the companion 2MASS J1207−3932b (L3 vl-g), which may reflect the difficulties of assigning a single number, namely spectral type, to this spectrally extreme object (e.g., see Figure 2 of Liu et al. 2013b).”
• ATLAS: A High-cadence All-sky Survey System (2018, background): “…square degrees) in 6 wavebands and is having a major impact—not only in transients and moving objects (Hsieh et al. 2012; Rest et al. 2014) but from low mass stars (Liu et al. 2013), through Milky Way stellar populations (Laevens et al. 2015) to the highest redshift quasars (Bañados et al. 2014).”
• Imaging Extrasolar Giant Planets (2016, background): “…low effective temperatures where older, high-gravity brown dwarfs have already transitioned to T dwarfs (Metchev & Hillenbrand 2006; Chauvin et al. 2004; Marois et al. 2008; Patience et al. 2010; Bowler et al. 2010a; Faherty et al. 2012; Bowler et al. 2013; Liu et al. 2013; Filippazzo et al. 2015).”
• FUNDAMENTAL PARAMETERS AND SPECTRAL ENERGY DISTRIBUTIONS OF YOUNG AND FIELD AGE OBJECTS WITH MASSES SPANNING THE STELLAR TO PLANETARY REGIME (2015, methodology): “…(18) Cruz et al. (2009), (19) Gizis et al. (2012), (20) Burgasser et al. (2006a), (21) Gagliuffi et al. (2014), (22) Scholz et al. (2009), (23) Liu et al. (2013), (24) Kirkpatrick et al. (2006), (25) Cushing et al. (2009), (26) Kirkpatrick et al. (1997), (27) Tinney (1993), (28) Burgasser et…”
• The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs (2020, background): “At colder temperatures, though, the mass range reduces dramatically, with the 300-450K bin containing only objects with masses below ∼ 30MJup.”
• BANYAN. II. VERY LOW MASS AND SUBSTELLAR CANDIDATE MEMBERS TO NEARBY, YOUNG KINEMATIC GROUPS WITH PREVIOUSLY KNOWN SIGNS OF YOUTH (2013, background): “2MASS J21140802–2251358 is a very red L7 object identified by Liu et al. (2013b) to be a planemo candidate member to βPMG.”
• BANYAN. VII. A NEW POPULATION OF YOUNG SUBSTELLAR CANDIDATE MEMBERS OF NEARBY MOVING GROUPS FROM THE BASS SURVEY (2015, background): “…longer wavelengths, causing young BDs to display similar absolute J magnitudes to those of field BDs around spectral type ∼L0, as well as absolute J magnitudes even fainter than those of field dwarfs at later spectral types (Faherty et al. 2012, 2013; Liu et al. 2013a; Zapatero Osorio et al. 2014).”
• Discovery of a warm, dusty giant planet around HIP 65426 (2017, background): “5-22, L7 member of β Pic, Biller et al. 2015; Liu et al. 2013) and WISE 0047, L6.”