A Moving Cluster Distance to the Exoplanet 2M1207b in the TW Hydrae Association

By Eric Mamajek. 2005

177 citations recorded by the source corpus.

A candidate extrasolar planet companion to the young brown dwarf 2MASSW J1207334-393254 (hereafter 2M1207) was recently discovered by Chauvin et al. They find that the temperature and luminosity of 2M1207b are consistent with a young, ~5MJ planet. The 2M1207 system is purported to be a member of the TW Hya association (TWA) and situated ~70 pc away. Using a revised space motion vector for TWA and improved proper motion for 2M1207, I use the moving cluster method to estimate the distance to the 2M1207 system and other TWA members. The derived distance for 2M1207 (53 ± 6 pc) forces the brown dwarf and planet to be half as luminous as previously thought. The inferred masses for 2M1207A and 2M1207b decrease to ~21 and ~3-4MJ, respectively, with the mass of 2M1207b well below the observed tip of the planetary mass function and the theoretical deuterium-burning limit. After removing probable Lower Centaurus Crux (LCC) members from the TWA sample, as well as the probable nonmember TWA 22, the remaining TWA membership is found to have distances of 49 ± 3 (s.e.m.) ± 12 (1 σ) pc and an internal one-dimensional velocity dispersion of 0.8 km s-1. There is weak evidence that the TWA is expanding, and the data are consistent with a lower limit on the expansion age of 10 Myr (95% confidence).

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/55abc474e6ef6745db7c62031ae69c9b944e0884

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In Astronomy and Astrophysics

1. Michael C. Liu
2. K. Luhman
3. Eric Mamajek
4. T. Dupuy
5. L. Hillenbrand
6. A. Kraus
7. S. Andrews
8. D. Wilner

Citations in the corpus

• BANYAN. XI. The BANYAN Σ Multivariate Bayesian Algorithm to Identify Members of Young Associations with 150 pc (2018, methodology): “TWA 19 AB is a young star that was defined as a candidate member of TWA by Mamajek (2005), but later listed as a likely contaminant from LCC by Gagné et al. (2017a) based on a preliminary version of BANYAN Σ.”
• TWO WIDE PLANETARY-MASS COMPANIONS TO SOLAR-TYPE STARS IN UPPER SCORPIUS (2010, result): “The absolute K-magnitude of 9.1 is then about 2 magnitudes brighter than for corresponding field objects, providing clear evidence of a larger radius and young age; this height above the main sequence is similar to that observed for other late-type members of Upper Sco (Lodieu et al. 2007) and TW Hy”
• PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS (2014, unknown): “— (1) Webb et al. (1999), (2) Navascués (2006) (3) Mamajek (2005), (4) Torres et al. (2006), (5) Weinberger et al. (2013), (6) Yee & Jensen (2010), (7) Binks & Jeffries (2014), (8) Malo et al. (2014b), (9) Mamajek & Bell (2014), (10) Torres et al. (2008), (11) Torres et al. (2000) (12) Zuckerman…”
• INTRINSIC COLORS, TEMPERATURES, AND BOLOMETRIC CORRECTIONS OF PRE-MAIN-SEQUENCE STARS (2013, methodology): “Assuming it is a member and adopting the TWA mean group space motions from Weinberger et al. (2012) of (U, V, W) = (-10.9±0.2, -18.2±0.2, -5.3±0.2) km s−1, we estimate a kinematic distance of 70.0±3.8 pc, based on the method discussed in Mamajek (2005).”
• FUNDAMENTAL PARAMETERS AND SPECTRAL ENERGY DISTRIBUTIONS OF YOUNG AND FIELD AGE OBJECTS WITH MASSES SPANNING THE STELLAR TO PLANETARY REGIME (2015, unknown): “…(18) Vrba et al. (2004), (19) Leggett et al. (2012), (20) Burgasser et al. (2008c), (21) Tinney et al. (2003), (22) Faherty et al. (2014), (23)Mamajek (2005), (24) Manjavacas et al. (2014), (25) Burningham et al. (2011), (26) Geballe et al. (2001), (27) van Altena et al. (1995), (28) van…”
• A STELLAR CENSUS OF THE TUCANA–HOROLOGIUM MOVING GROUP (2014, background): “• Radial velocities: By definition, young moving groups are comoving with a very small velocity dispersion (σ ∼1 km/s for TWA; Mamajek 2005), and hence the radial velocities of Tuc-Hor members should correlate very well with the projection of the group UVW velocity into the line of sight.”
• BANYAN. II. VERY LOW MASS AND SUBSTELLAR CANDIDATE MEMBERS TO NEARBY, YOUNG KINEMATIC GROUPS WITH PREVIOUSLY KNOWN SIGNS OF YOUTH (2013, background): “Faherty et al. (2012) measure a distance of 28.5± 3.5 pc for this object, and Weinberger et al. (2013a) measure 42.0± 4.5 pc. Mamajek (2005) measure a radial velocity of 11.6±2 km s−1 and propose it as a TWA member.”
• THE DISK POPULATION OF THE TAURUS STAR-FORMING REGION (2009, background): “…Lawson et al. 2002; Gizis 2002; Feigelson et al. 2003; Luhman & Steeghs 2004; Luhman 2004a; Lyo et al. 2004; Song et al. 2004; Zuckerman & Song 2004; Mamajek 2005; Scholz et al. 2005; Looper et al. 2007; Luhman et al. 2008a; Kastner et al. 2008) and young late-type dwarfs in the solar…”
• EMPIRICAL CONSTRAINTS ON TURBULENCE IN PROTOPLANETARY ACCRETION DISKS (2010, methodology): “…Procedure We assume that the disks have a Keplerian velocity field, using stellar masses and distances from the literature to model the rotation pattern (0.6M⊙ at 51 pc for TW Hya and 2.3M⊙ at 122pc for HD 163296; see Calvet et al. 2002; Webb et al. 1999; Mamajek 2005; van den Ancker et al. 1998).”
• THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS (2016, background): “Weinberger et al. (2013) and Ducourant et al. (2014) also report parallaxes for this object of 23.8± 2.6mas and 26.2± 1.1mas, respectively, which agree with ours at 0.1σ and 1.3σ (as does the Mamajek 2005 kinematic parallax of 25.0 ± 2.5 mas).”
• A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood (2015, methodology): “…for assigning distances to each star, however in cases where these are not available or the associated uncertainties are prohibitively large, we adopt either a kinematic distance from the literature or derive one using the so-called ‘convergent point’ method (de Bruijne 1999; Mamajek 2005).”
• THE GEMINI/NICI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF PLANETS AROUND YOUNG MOVING GROUP STARS (2013, unknown): “…et al. 1999; Jayawardhana et al. 1999; Zuckerman et al. 2001c, 2004; Gizis 2002; Song et al. 2002, 2003; Kastner et al. 2008; Scholz et al. 2005; Mamajek 2005; Looper et al. 2007; Torres et al. 2008; Fernández et al. 2008; da Silva et al. 2009; Looper et al. 2010a, 2010b; Rodriguez et al.…”
• AN OPTICAL SPECTROSCOPIC STUDY OF T TAURI STARS. I. PHOTOSPHERIC PROPERTIES (2014, background): “However, even if the estimated age of a single star were younger, the dynamical age and cluster age are both consistent with 7–10 Myr (e.g. Mamajek 2005; Ducourant et al. 2014).”
• The star formation history and accretion-disc fraction among the K-type members of the Scorpius–Centaurus OB association (2016, methodology): “We adopt the formalism and methods of Mamajek (2005) and adopt the updated Sco-Cen subgroup space motions listed in Chen et al. (2011).”
• BAYESIAN ANALYSIS TO IDENTIFY NEW STAR CANDIDATES IN NEARBY YOUNG STELLAR KINEMATIC GROUPS (2012, methodology): “TWA TWA 19: This star (G5V) was rejected as a member of TWA and suggested instead to be member of the ScorpiusCentaurus complex by Mamajek (2005) and Torres et al. (2008).”
• The Ages of Stars (2007, methodology): “Another limitation is that some young groups appear to have little net expansion (Mamajek (2005); Makarov (2007)), so that a time when the members were closest together is illdefined.”