1 / 21

Photometric Observation of 107P/4015 Wilson-Harrington

Photometric Observation of 107P/4015 Wilson-Harrington. 우라카와 세이다로 Сейтаро Урак а ба. Seitaro Urakawa 1 , Shin-ichiro Okumura 1 , Kota Nishiyama 1 , Tsuyoshi Sakamoto 1 , Masateru Ishiguro 2 , Kouhei Kitazato 3 , Daisuke Kuroda 4 , Sunao Hasegawa 5 , Makoto Yoshikawa 1,5

keiki
Download Presentation

Photometric Observation of 107P/4015 Wilson-Harrington

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Photometric Observation of 107P/4015 Wilson-Harrington 우라카와 세이다로 Сейтаро Уракаба Seitaro Urakawa1, Shin-ichiro Okumura1, Kota Nishiyama1, Tsuyoshi Sakamoto1, Masateru Ishiguro2, Kouhei Kitazato3, Daisuke Kuroda4, Sunao Hasegawa5, Makoto Yoshikawa1,5 (1Japan Spaceguard Association, 2Seoul University, 3Aizu University, 4National Astronomical Observatory of Japan, 5ISAS(Institute of Space and Astronautical Science)/JAXA(Japan Aerospace Exploration Agency)

  2. Outline • Introduction Asteroid Explorer Hayabusa Primitive Body Missions of Japan • 107P/4015 Wilson-Harrington • Observations • Data Reduction • Results (Rotational Period; Rotational Direction; Pole Direction; Shape Model ) • Summary

  3. Welcome Home Asteroid ExplorerHayabusa June 13, 2010 Asteroid explore Hayabusa return to the earth.

  4. Welcome Home Asteroid ExplorerHayabusa Sep 12, 2005: Arrive asteroid Itokawa Nov, 2005: Two times touch down and collect the sample. May 9, 2003: Lift off

  5. Welcome Home Asteroid ExplorerHayabusa June 13 , 2010, at 14:08 (UT) Touch down in Australia June 13 , 2010, at 10:54 (UT) Capsule release

  6. Scientific Purpose of Hayabusa Mission Primitive bodies (asteroids and comets) have not accepted much thermal influences since the early stage of solar system. In addition to it, the objects have not been weathered. Asteroids and comets preserve the condition at the birth of solar system. We can obtain a clue on the birth of solar system by analyzing the samplein detail.

  7. Taxonomy of Asteroids Inner asteroid belt: S-type asteroids are dominated. Center asteroid belt: C-type asteroids are dominated. S-type asteroid: Silicate component C-type asteroid: Carbonaceous component Outer asteroid belt (Trojan): D-type asteroids increases. D-type asteroid: More primitive component, Organic matter, Comet survivors!?

  8. Primitive Body Missions of Japan D-type or Dormant Comets C-type S-type Hayabusa Itokawa Hayabusa Mk2 Wilson-Harrington (Candidate) Hayabusa 2 1999 JU3 More Primitive Body More Difficult Mission

  9. Hayabusa Mk2 mission New Explorer (Development of new ion engine) Candidate of target: D-type or Dormant comet (for example 107P/4015 Wilson-Harrignton) The mission can provide insights on the unknown link between asteroids and comets. In order to design the mission, the physical properties of WH (rotational period, rotational direction, pole direction, shape) are needed. Such physical properties are obtained by the photometric observation (the light-curve of WH).

  10. Fernandez et al. 1997 107P/4015 Wilson-Harrington A comet was discovered in 1949 at the Palomar observatory. The faint tail can see. The comet named as 107P/Wilson-Harrington. However, the comet was lost by the insufficient observation. A near earth asteroid (4015) was discovered in 1979. Semi-major axis 　2.638AU Eccentricity0.624 Inclination　 2.78° Argument of perihelion　91.25° Longitude of ascending node　270.57° Period 　　　　　　 4.28 year The continuous observations identified that 107P/Wilson-Harrington and asteroid (4015) were the same object.

  11. P=3.556h Harris and Young 1983 P=6.1h Osip and Campine1995 Past Study of Wilson-Harrington Rotational period: two solutions for 0.148 day (3.556 hour) or 0.254 ±0.002day (6.1 ±0.05 hour) Spectral type: C-type (NASA/JPL database) Rotational direction: unknown Pole direction: unknown Shape: unknown

  12. Okayama Astrophysical Observatory 0.5m (PI: Dr.Kuroda) Nov 7, 2009 – Dec 21, 2009 / 19 days Observations Kiso Observatory 1.05m (PI: Dr.Kitazato) Aug 17, 19, 20, Dec 12, 2009 / 4 days Bise Spaceguard Center 1.0m Sep 6, 2009 – Mar 11, 2010 / 43 days Lulin Observatory 1.0m (PI: Dr.Kitazato) Dec 7-10, 2009 / 4 days University of Hawaii 2.2m (PI: Dr.Ishiguro) Dec 18, 2009

  13. Data Reduction • Bias and flat field calibration • Aperture photometry (IRAF) • Relative photometry by using reference stars

  14. Rotational Period Method of period analysis: Lomb-Scargel Periodgram (Lomb 1976 & Scargel 1982). We use the photometric precise data (Data of December). Candidate 1: 0.2592 day Candidate 2: 0.2979 day Candidate 3: 0.0993 day

  15. Rotational Period Results: 0.2979day (7.15 h) *The past data consist with the period of candidate 2 (0.2979 day). When we made the folded light-curve with other candidates, the shape of light-curve was not good. *Unusual six-peak light-curve (The light-curve represented the cross section area of asteroid. When the shape of asteroid is an ellipsoidal body, the shape of typical light-curve is double-peak.)

  16. Rotational Direction Appearance Rotation (Red circled asteroid) True Rotation (Green circled asteroid) ≠ Appearance Rotation : The rotation is determined by the light-curve. Retrograde rotation True Rotation : The rotation is slightly shorter or longer than the appearance rotation. Prograde rotation Prograde rotation: The true period is shorterthan the appearance period. Asteroid Retrograde rotation: The true period is longer than the appearance period. Observer

  17. Prograde Retrograde Rotational Direction We calibrated the difference between the appearance rotation and the true rotation. Assume retrograde rotation Assume prograde rotation The light-curve shape is good. The light-curve shape is not good.

  18. Determination of Pole Direction by Epoch Method Epoch method (Magnusson 1986): Phase shift in the light-curve→　Pole direction Phase shift (Observational values) Phase shift (Theoretical values) (T : The time when a specific feature (for example, the flux minimum) appears, P: Rotational Period, n: Number of rotation during the observation term, θ: A vector that is related with the pole direction. We search θ value which minimizes the residuals between the left-hand and the right-hand.

  19. Determination of Pole Direction by Epoch Method Candidate 1 λ: 320°±15 β: -20 °±15 Candidate 2 λ=140±15° β= -20±15

  20. Shape Model Light-curve →　Shape Model (The software is developed and distributed by Kassalainen et al. 1992.) edge on pole on Like hexagonal shape

  21. Summary • We introduced the primitive body mission of Japan. →The target candidate of Hayabusa Mk2 is 107P/4015 Wilson-Harrignton. • We found the following properties from the light-curve of WH, Rotational period: 0.2979 day (7.15 hour)→Hayabusa Mk2 can touch down. Rotational direction: Retrograde rotation Pole direction: (λ,β）=(320°,-20 °) or (140°,-20 °) Shape: Like hexagonal shape • In order to calculate the precise rotational period, it is important to observe the target from multi-longitude location. WH is not the only target. There is the possibility of the target change. We would like to collaborate with Maidanak observatory and other observatories for the next ground-base observation campaign.

More Related