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Probing trans-Neptunian Objects Probing trans-Neptunian Objects - - PowerPoint PPT Presentation

Dec 11, 2023 483 likes •911 views

Probing trans-Neptunian Objects Probing trans-Neptunian Objects with stellar occultations in Gaia occultations in Gaia era era with stellar Bruno Sicardy Observatoire de Paris - LESIA & universit Pierre et Marie Curie Solar system

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Probing trans-Neptunian Objects Probing trans-Neptunian Objects with stellar with stellar occultations in Gaia

  • ccultations in Gaia era

era Bruno Sicardy Observatoire de Paris - LESIA & université Pierre et Marie Curie Solar system science before and after Gaia Pisa 4-6 May 2011

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Doressoundiram & Lellouch, "Aux confins du système solaire"

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 radius, shape & limb features at kilometric accuracy  density, if mass known from satellite motion ---> internal

structure

 albedo ---> composition, state of surface  if double occultation primary/secondary: accuracy ~ 10 km,

e.g. Pluton/Charon ---> better orbital elements airless Trans-Neptunian Objects (TNO's)

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 density & temperature profiles down to nbar levels  variations with time  detection of activity ( e.g. gravity waves)  zonal winds measurements through central flash  haze properties through chromatic dependence

TNO's with atmosphere

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 strength: can achieve what nobody else can do  weakness: difficult to predict, and thus to plan,

especially on large telescopes ⇒ depending on body and background stellar field:

  • ne occultation of interest every month, year,

decade

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New York Times 11 January 2011: "The War of the Worlds, Round 2"

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Haumea Makemake

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Haumea Makemake

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~ 3x3 arcmin fields of view Pluton ~ 240 candidates in 2011 Eris ~ 1 candidate 06 Nov. 2010 next: 29 August 2013

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thousands of stars measured against UCAC2 stars positions → r.m.s. deviations ~ 50 mas THEN updates 1-3 weeks before → accuracy 20-30 mas

  • M. Assafin et al. (ON, Rio de Janeiro)
  • R. Behrend (Geneva Obs)

J.L. Ortiz et al. (IAA Granada)

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www.lesia.obspm.fr/perso/bruno-sicardy/

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rms 20 mas rms 40 mas

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0.033 arsec (33 mas) stamp at 140 km Pluton Charon Eris Makemake Titan quaoar

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       

2003 AZ84

 

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0.89"

2UCAC 26257135 (D. Herald, Aug. 2004)

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Charon

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Sicardy et al., Nature 439, 52, 2006 « Charonʼs size and an upper limit

  • n its atmosphere from a stellar
  • ccultation »

R= 603.6±1.4 km

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45 mas (∆t= 36 sec)

distance: 42.75 UA

São Luis Quixadá

  • bserved

predicted Rio de Janeiro group & Raoul Behrend (Geneva)

Varuna

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São Luis, Maranhão, Brazil,February 2010, F. Colas

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Mangrove, São Luis, from http://www.blogg.org/blog-16247-offset-415.html São Luis, Brazil telescope 12.5 cm, alt.: 2 m

  • F. Colas
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52.5 sec São Luis

  • F. Colas

Quixadá

  • F. Braga Ribas
  • F. Vachier

something expected at Quixadá around here clouds…

1 1

UT (sec) flux ratio

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dark (pv=0.04) least elongated probability ~ 0 610x525 km dark (pv=0.04) most elongated probability ~ 0.3 860x375 km brightest possible (pv=0.12) probability ~ 0 502x218 km

most probable in this corner

São Luis Quixadá

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6 novembre 2010, Sicardy et al. Nature 2011, to be submitted

Eris

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Alain Maury, 50 cm Sand Pedro de Atacama Emmanuel Jehin, 60 cm La Silla

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most remote object observed in solar system (97 UA, 15 billions km) pV close to one → one of brightest objects of solar system atmospheric limit of N2~ 1 nanobar (10-4 × Pluton atmosphere) Pluto min. radius

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2006 2010 Eris no!

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Mike W… 4 decembre 2010, 14:03 Dear Mr. Sikardy,[…] I am an artist/writer/attorney and have loved Pluto since I first learned about as a little boy. I asked President George W. Bush in July 2002 when I met him in Portland, Oregon […] Anyway, I am very glad that Eris will lose more diameter based on the final calculations

  • f the stellar occultation. Given

the bad behavior of Mike "Pluto-Killer" Brown, it would make it even more joyous, I must admit, if Eris were to lose enough diameter to make it virtually certain that Pluto is

  • larger. Alan Stern told me that

New Horizons, baring a mishap, will measure Pluto's diameter, too.

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2003 AZ84

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~60 mas

2003 AZ84

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Makemake

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~60 mas

Makemake

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VLT NTT

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Quaoar

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~30 mas

Quaoar

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Quaoar, San Pedro de Atacama 50-cm, 4 May 2011

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UCAC2 catalog + update + Pluto ephemeris correction UCAC2 catalog + update + Pluto ephemeris correction ABOUT 1400 EVENTS posted

  • n B. Sicardy's home page
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www.lesia.obspm.fr/perso/bruno-sicardy/

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Conclusions Conclusions TNOs TNOs occultations in Gaia's

  • ccultations in Gaia's

era era at < 1 mas accuracy:

huge relieve in occultation planning (now 99% time

spent in astrometric predictions & updates)

 chose TNO, chose telescope, get many chords on body

(size, shape & limb features at km-accuracy)

 TNOs with atmosphere (Pluto,…): central flash → zonal

winds, haze properties

 get satellites: shape & orbital elements

photo Alain Maury