J/ApJ/794/159 Statistical analysis of exoplanet surveys (Brandt+, 2014) ================================================================================ A statistical analysis of SEEDS and other high-contrast exoplanet surveys: massive planets or low-mass brown dwarfs? Brandt T.D., McElwain M.W., Turner E.L., Mede K., Spiegel D.S., Kuzuhara M., Schlieder J.E., Wisniewski J.P., Abe L., Biller B., Brandner W., Carson J., Currie T., Egner S., Feldt M., Golota T., Goto M., Grady C.A., Guyon O., Hashimoto J., Hayano Y., Hayashi M., Hayashi S., Henning T., Hodapp K.W., Inutsuka S., Ishii M., Iye M., Janson M., Kandori R., Knapp G.R., Kudo T., Kusakabe N., Kwon J., Matsuo T., Miyama S., Morino J.-I., Moro-Martin A., Nishimura T., Pyo T.-S., Serabyn E., Suto H., Suzuki R., Takami M., Takato N., Terada H., Thalmann C., Tomono D., Watanabe M., Yamada T., Takami H., Usuda T., Tamura M. =2014ApJ...794..159B (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Stars, dwarfs ; Stars, double and multiple ; Planets ; Stars, ages Keywords: brown dwarfs - methods: statistical - open clusters and associations: general - planetary systems stars: activity - stars: imaging Abstract: We conduct a statistical analysis of a combined sample of direct imaging data, totalling nearly 250 stars. The stars cover a wide range of ages and spectral types, and include five detections ({kappa} And b, two ~60 M_J_ brown dwarf companions in the Pleiades, PZ Tel B, and CD-35 2722B). For some analyses we add a currently unpublished set of SEEDS observations, including the detections GJ 504b and GJ 758B. We conduct a uniform, Bayesian analysis of all stellar ages using both membership in a kinematic moving group and activity/rotation age indicators. We then present a new statistical method for computing the likelihood of a substellar distribution function. By performing most of the integrals analytically, we achieve an enormous speedup over brute-force Monte Carlo. We use this method to place upper limits on the maximum semimajor axis of the distribution function derived from radial-velocity planets, finding model-dependent values of ~30-100 AU. Finally, we model the entire substellar sample, from massive brown dwarfs to a theoretically motivated cutoff at ~5 M_J_, with a single power-law distribution. We find that p(M,a){prop.to}M^-0.65+/-0.60^a^-0.85+/-0.39^ (1{sigma} errors) provides an adequate fit to our data, with 1.0%-3.1% (68% confidence) of stars hosting 5-70 M_J_ companions between 10 and 100 AU. This suggests that many of the directly imaged exoplanets known, including most (if not all) of the low-mass companions in our sample, formed by fragmentation in a cloud or disk, and represent the low-mass tail of the brown dwarfs. Description: We merge five samples to create our high-contrast data set: three published subgroups of the Strategic Exploration of Exoplanets and Disks with Subaru project (SEEDS; Tamura 2009, Exoplanets and Disks: Their Formation and Diversity (AIP Conf. Ser. 1158), ed. T. Usuda, M. Tamura, & M. Ishii (Melville, NY: AIP), 11), the GDPS (Lafreniere et al. 2007, J/ApJ/670/1367), and the moving groups targets from the NICI survey (Biller et al. 2013, J/ApJ/777/160). In total, our merged survey contains 248 unique stars with spectral types ranging from late B to mid M, at distances from ~5 pc to ~130 pc, with sensitivities down to ~1 MJ around the nearest, youngest targets. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 79 249 Age Distributions of All Targets -------------------------------------------------------------------------------- See also: V/70A : Nearby Stars, Preliminary 3rd Version (Gliese+ 1991) III/182 : HDE Charts: positions, proper motions (Nesterov+ 1995) I/239 : The Hipparcos and Tycho Catalogues (ESA 1997) J/ApJ/670/1367 : Gemini Deep Planet Survey (Lafreniere+, 2007) J/MNRAS/408/2457 : Low-mass stars and brown dwarfs in Praesepe (Baker+, 2010) J/ApJ/777/160 : NIR imaging survey for planets around MG stars (Biller+, 2013) Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 23 A23 --- Name The HIP, HD, GJ, or other source identifier 25- 26 I2 h RAh Hour of Right Ascension (J2000) 28- 29 I2 min RAm Minute of Right Ascension (J2000) 31- 34 F4.1 s RAs Second of Right Ascension (J2000) 36 A1 --- DE- Sign of the Declination (J2000) 37- 38 I2 deg DEd Degree of Declination (J2000) 40- 41 I2 arcmin DEm Arcminute of Declination (J2000) 43- 44 I2 arcsec DEs Arcsecond of Declination (J2000) 46- 49 I4 Myr Age5 Age at Posterior cumulative distribution function (CDF) Value 5% 51- 54 I4 Myr Age10 Age at Posterior CDF Value 10% 56- 59 I4 Myr Age25 Age at Posterior CDF Value 25% 61- 64 I4 Myr Age50 Age at Posterior CDF Value 50% 66- 69 I4 Myr Age75 Age at Posterior CDF Value 75% 71- 74 I4 Myr Age90 Age at Posterior CDF Value 90% 76- 79 I4 Myr Age95 Age at Posterior CDF Value 95% -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 16-May-2017