J/AJ/163/219 Gaia DR2 stellar flybys in the Sco-Cen OB association (Ma+, 2022) ================================================================================ Search for Stellar Flybys in the Sco-Cen OB Association with the Gaia DR2. Ma Y., De Rosa R.J., Kalas P. =2022AJ....163..219M ================================================================================ ADC_Keywords: Associations, stellar; Stars, masses; Radial velocities Keywords: Celestial mechanics ; Close encounters ; Debris disks ; Circumstellar disks Abstract: High-contrast imaging studies of debris disks have revealed a significant diversity in their morphologies, including large-scale asymmetries. Theories involving stellar flybys, an external source of gravitational disturbance, have offered a plausible explanation for the origin of these morphological variations. Our study is an experiment to gain empirical evidence that has been lacking from such theories. We explore this paradigm by using astrometric and radial velocity measurements from the Gaia DR2 and ground-based observations to trace the trajectories of 625 stars in the Sco-Cen OB association from 5Myr in the past to 2Myr in the future. We identified 119 stars that had at least one past flyby event occurring within one Hill radius, and 23 of these experienced flybys within 0.5 Hill radii. We found no evidence of a significant correlation between the presence of flyby events and infrared excess detections, although the sample is not uniformly sensitive to infrared excess emission. Ten stars that had past flyby events host resolved circumstellar disks that appear relatively symmetric in the existing data except for the circumbinary disk surrounding HD106906. We determined the trajectory and relative velocity of each of these flyby events and compared these to the geometry of the spatially resolved disks. Future work is needed to measure the kinematics of lower-mass stars and to improve sensitivity to circumstellar disks for the entire sample. Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 16 15 -24.2 Sco-Cen = NAME Upper Sco-Cen 16 12 -23.4 USCO = NAME Upper Sco Association ---------------------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 123 67 Events identified from Sco-Cen sample table3.dat 123 113 Events identified from USCO sample table4.dat 105 76 Events involving candidates and field stars with d_ca_<1pc and v_rel_<10km/s table5.dat 123 30 Simulated Potential Flyby events from USCO sample table6.dat 119 462 RV measurements of 462 Sco-Cen stars table7.dat 119 219 RV measurements of USCO sample -------------------------------------------------------------------------------- See also: B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2020) III/190 : WEB Catalog of Radial Velocities (Duflot+ 1995) III/254 : 2nd Cat. Radial Velocities with Astrometric Data (Kharchenko+, 2007) III/272 : RAVE 4th data release (Kordopatis+, 2013) I/345 : Gaia DR2 (Gaia Collaboration, 2018) J/A+AS/118/231 : Velocities & rotation of CP stars (Levato+, 1996) J/AJ/117/354 : OB associations from Hipparcos (de Zeeuw+, 1999) J/A+A/356/541 : T Tauri stars in the Sco-Cen OB association (Koehler+, 2000) J/A+A/460/695 : Search for Associations Containing Young stars (Torres+, 2006) J/AN/328/889 : Mean Radial Velocities of open clusters (Kharchenko+, 2007) J/A+A/480/L33 : Radial velocities of HD 4113 and HD 156846 (Tamuz+, 2008) J/A+A/524/A25 : Radial Velocities on 6 exoplanet host stars (Triaud+, 2010) J/ApJ/738/122 : ScoCen debris disks Around F- and G-type stars (Chen+, 2011) J/ApJ/745/56 : Upper Sco members rotational velocities (Dahm+, 2012) J/ApJ/758/31 : IR photometry for members of Upper Sco (Luhman+, 2012) J/AJ/144/8 : Spectro. of ~100 G/K/M-type Sco-Cen complex memb (Song+, 2012) J/ApJS/208/9 : Intrinsic colors and temperatures of PMS stars (Pecaut+, 2013) J/ApJ/785/47 : Sources around target stars Upper Scorpius (Lafreniere+, 2014) J/A+A/573/A126 : VLT/NaCo Large program I. Sample (Desidera+, 2015) J/ApJ/827/142 : ALMA observations of GKM stars in Upper Sco (Barenfeld+, 2016) J/ApJS/225/15 : IR excess stars from Tycho-2 and AllWISE (Cotten+, 2016) J/MNRAS/461/794 : Scorpius-Centaurus K-Type Stars (Pecaut+, 2016) J/ApJ/840/87 : Young star systems observed with SALT (Riedel+, 2017) J/A+A/616/A37 : Close encounters to the Sun in Gaia DR2 (Bailer-Jones+, 2018) J/ApJ/856/23 : BANYAN. XI. The BANYAN {Sigma} algorithm (Gagne+, 2018) J/AJ/156/194 : Orbits double-lined pairs in multiple stars (Tokovinin, 2018) J/A+A/623/A112 : The Sco OB2 population from Gaia DR2 data (Damiani+, 2019) J/AJ/157/78 : Double &multiple star systems GaiaDR2 (Jimenez-Esteban+, 2019) J/A+A/640/A73 : pi Men radial velocity curves (De Rosa+, 2020) J/AJ/160/24 : Circumstellar dust of 104 stars with GPIES (Esposito+, 2020) J/A+A/633/A82 : Disks around T Tauri stars with SPHERE. II. (Garufi+, 2020) J/ApJS/247/66 : SUPERWIDE; wide binaries in Gaia & SUPERBLINK (Hartman+, 2020) J/A+A/636/A116 : VLTI/PIONIER images of 15 Herbig Ae/Be stars (Kluska+, 2020) J/AJ/160/44 : Upper Scorpius spectroscopy and photometry (Luhman+, 2020) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table[235].dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 23 A23 --- Star1 Star 1 identifier 25- 47 A23 --- Star2 Star 2 identifier 49- 53 F5.2 km/s RVel ? Simulated radial velocity (1) 55- 59 F5.2 Myr Tca Time of closest approach 61- 64 F4.2 Myr e_Tca Lower uncertainty in tca 66- 69 F4.2 Myr E_Tca Upper uncertainty in tca 71- 74 F4.2 pc Dca Distance of closest approach 76- 79 F4.2 pc e_Dca Lower uncertainty in dca 81- 84 F4.2 pc E_Dca Upper uncertainty in dca 86- 89 F4.2 --- dca/RH-T Ratio of closet approach to target Hill radius 91- 94 F4.2 --- e_dca/RH-T Lower uncertainty in dca/RH,T 96- 99 F4.2 --- E_dca/RH-T Upper uncertainty in dca/RH,T 101-104 F4.2 --- dca/RH-F Ratio of closet approach to flyby Hill radius 106-109 F4.2 --- e_dca/RH-F Lower uncertainty in dca/RH,F 111-114 F4.2 --- E_dca/RH-F Upper uncertainty in dca/RH,F 116-120 A5 --- Cat Category (2) 122-123 A2 --- IREx? Infrared excess detected (3) -------------------------------------------------------------------------------- Note (1): For Simulated Potential Flyby (SPF) of the flyby star, which do not have RVel measurement, that outputs the minimum d_ca_. Note (2): Categories as follows: T = Ecounters with 0.5