Solar System Astrometry

Carlos E. LopezUniversidad Nac. de San Juan, Argentina, and

Yale Southern Observatory

Measuring the Positions of:

AsteroidsCometsNatural SatellitesSpace DebrisOccultations

Ptolomy’s Solar System

Copernicus’s scheme of the Solar System

The Solar System Before 1801(and after the Copenican theory had been accepted)

Ceres

The Solar System on Jan 1st, 1801

The Solar System as of Jun 8, 2005

around 150,000 objects

The Kuiper belt is thought to be the source of short-

period comets and of centaurs. It is named after

Gerard Kuiper who predicted its existence in 1951 but

is also sometimes referred to as the Edgeworth-

Kuiper belt, in recognition of the amateur astronomer

Kenneth Edgeworth (1880-1972) who, in his only

scientific paper, published in the Journal of the British

Astronomical Association in 1942, was the first to

suggest the existence of a region of comet-like

objects beyond the outer planets. The first

observational support for it came in 1992 when David

Jewitt of the University of Hawaii and Jane Luu of the

University of California, Berkeley discovered a 200-

kilometer-wide object circling the Sun beyond the

orbit of Pluto.

An Outer Belt?

Orbit of 1996 TL66

The Outer Solar System by the End of 1999

As of Jul 12, 890 objects have been As of Jul 12, 890 objects have been

identified. It is assumed there must be on identified. It is assumed there must be on

the order of 70,000 such objects.the order of 70,000 such objects.

The first TNO ever discovered was 1992 The first TNO ever discovered was 1992

QB1.QB1.

The last one to be discovered was 2005 The last one to be discovered was 2005

JR179.JR179.

How many TNOs have been identified so far?

1801 1 1999 167941802 1 2000 253301804 1 2001 132961807 1 2002 55971845 1 2003 10551847 3 2004 260

Discovery rate

The name of an Asteroid could be:

TemporaryProvisionalPermanent

Provisional Designations

Provisional Designations (cont.)

If there are more than 25 discoveries in any one half-month

period, the second letter is recycled and a numeral `1' is added to

the end of the designation. If more than 50 discoveries, the second-

letter is again recycled, with a numeral ‘2' appended after the

second letter. Discoveries 76-100 have numeral ‘3' added, numbers

101-125 numeral `4', etc. When possible, these additional numbers

should be indicated using subscript characters.

Thus the order of assignment of designations in a particular half-

month period is as follows: 1995 SA, 1995 SB, ..., 1995 SY, 1995 SZ,

1995 SA1, ..., 1995 SZ1, 1995 SA2, ..., 1995 SZ9, 1995 SA10, etc.

J95X00A = 1995 XA J95X01L = 1995 XL1 J95F13B = 1995 FB13 J98SA8Q = 1998 SQ108 J98SC7V = 1998 SV127 J98SG2S = 1998 SS162 K99AJ3Z = 2099 AZ193

The provisional designations stored on the orbit and observations is stored in a 7-character packed format

2005 OH = 5O5604D(July 20.49 UT) 2005 OE = 5O3EC49(July 19.47 UT) 2005 OB = 77G001 (July 18.37 UT) 5NA1C16 does not exist (July 17.93 UT) P03DDA does not exist (July 17.49 UT) 2005 NP82 = 5N5545E(July 17.49 UT) 2005 NW80 = SW40Pz (July 16.66 UT) 2005 NV80 = UHAZ01 (July 16.66 UT)

From temporary to provisional designations

Asteroids: Areas for Study

Shape and StructureCompositionMassSurface StructureMoonsMagnetometry

Classification of Asteroids

The classification can be made from two very different points

of view:

Location within the Solar System

Physical characteristics

Physical Characteristics (main classes only)

C class: they have a dark appearance, implying a composition of rocky material mixed with dark carbon compounds. This class is thought to consist of primitive matter. S class: this is a rather small group –compared with the C ones. They are more reflective and show a preponderance of silicate rock. This is the S class, which stands for stony class. M class: this group consists of bodies with large amounts of metal, such as iron and nickel. Apparently these asteroids come from differentiated bodies that have fractured by collisions. V class: a small number of asteroids have basaltic surfaces. These basaltic asteroids evidently had great flows of lava. D class: a few asteroids having a dark surface. In fact the surface of many of these is dark red. Several of these asteroids, beyond the orbits of Saturn, are called Centaur asteroids.

Distribution of Inclinations

Kirkwood Gaps

Dsitribution of the Lagrangian Points

Mercury

Venus

Earth Mars

The Inner Most Solar System

Sun

Classification of NEAs

H Diameter H Diameter H Diameter

Conversion Between Absolute Magnitude (H) and Diameter

"The potential catastrophe of an asteroid hitting Earth should no

longer be ignored. We need to know what is out there. Accounts

of asteroids passing close to Earth with almost no prior warning

should be enough to get our attention. The first step is to assess

the threat. Given the vast number of asteroids and comets that

inhabit the Earth's neighborhood, greater efforts for tracking

and monitoring these objects are critical. This bill would direct

NASA to expand their current program to track and detect

potential threats and would provide a funding authorization. Any

threat that would wreak havoc on or world should be studied

and prevented if possible. We have the technology, we need the

direction - this bill provides that."

Rep. Rohrabacher

The Beginning

"All of these bills will improve our lives through

increasing our understanding of the Earth, how it

works and what may threaten it."

Science Committee Chairman Sherwood Boehlert

The Beginning (cont.)

Search Programs

The Discovery Channel Telescope

The only requirements for participation in the FMO project are 1) interest, 2)

sharp eyes and 3) access to a computer during the hours that the

Spacewatch mosaic system is in operation. If you are interested in

participating, please refer to How to Find FMOs for more information.

The Ritcher’s Scale of Asteroid Impacts

Upcoming Ecounters

How Many NEAs are there?

286 Atens1662 Apollos1471 Amors

IAU Minor Planet Center

IAU Minor Planet Center

IAU Minor Planet Center

IAU Minor Planet Center

Results should be submitted in the MPC format:

COD (observatory code) (YSO = 808) CON (followed by the contact details) OBS (followed by the list of observers) MEA (followed by the list of measurers) TEL (followed by details of the telescope) NET (followed by the abbreviated name(s) of the catalogue(s) used for the reductions). BND (followed by single character representing the mag band) COM (followed by a textual comment) NUM (followed by a count of the observations in this batch)

P Photographic (default if column is blank) E Encoder C CCD T Meridian or transit circle M Micrometer V/v "Roving Observer" observation R/r Radar observation S/s Satellite observation c Corrected-without-republication CCD observation

Accepted Detectors

USNO SA2.0USNO A2.0Tycho 2ACTUCAC 2USNO B1.0GSC 2.2

Reference Catalogues Recommended by the IAU Minor

Planet Center

Image mining

SkyMorph: image mining facility for moving

objects

Addition of the three previous singlets

Asteroid 2002 NT7 detected by NEAT

The DSS Plate Finder

1999 AN10

POSS Image obtained in 1955, 34 years before the official discovery of the asteroid!!!

A new asteroid?

1955 1953

Radar-Detected Asteroids

97 Main-Belt Asteroids

175 Near-Earth Asteroids

High-resolution Model of Asteroid 4179 Toutatis

Radar Observations

Hudson, R. et al., 2003, Icarus, 161, 346

Current Status

Coming Radar Observations

Radar Observations (cont.)

Major Planets and Satellites

Galileo’s notes on the discovery of the “Medicean planets”

On the 7th day of January in the present year, 1610, … I noticed a circumstance which I had never been able to notice before, namely that three little stars, small but very bright, were near the planet; and although I believed them to belong to a number of the fixed stars, yet they made me somewhat wonder, because they seemed to be arranged exactly in a straight line, parallel to the ecliptic… I therefore concluded, that there are three stars in the heavens moving about Jupiter, as Venus and Mercury around the Sun …

Orbits of Jupiter’s Known Satellites

Discovery Images of S/2000 J8(taken with the University of Hawaii 88-inch

telescope + 8-K CCD Camera)

Pascu, D. et al. 1987. AJ 93, 963-1007.

Veiga, C., and Vieira Martins. 1995, A&ASS, 111, 387-392

Contour Density of Uranus and …

…Miranda

Veiga, C., and Vieira Martins. 1995, A&ASS, 111, 387-392

Veiga, C., and Vieira Martins. 1995, A&ASS, 111, 387-392

Observing Mars Satellites

Colas, F., and Arlot, J. 1991, A&A, 252, 402

Space Debris

1. In its resolution 51/123, paragraph 32, of 13 December 1996, the General

Assembly considered it essential that Member States pay more attention to

the problem of collisions of space objects, including nuclear power sources,

with space debris, and other aspects of space debris, and called for the

continuation of national research on that question, for the development of

improved technology for the monitoring of space debris and for the

compilation and dissemination of data on space debris. To the extent

possible, the Assembly considered that information thereon should be

provided to the Scientific and Technical Subcommittee of the Committee on

the Peaceful Uses of Outer Space.

Low Earth Orbits (between the surface of the Earth and 2,000 km)

Geosynchronous Region (around 35,785 km altitude)

Since 1961, more than 170 man-made objects in Earth orbit have undergone moderate to serious breakups.

Another 40 have undergone less energetic debris-

producing events. Only three of these fragmentations are known to have

been caused by deliberate or accidental collisions. The vast majority of fragmentations appear to have

arisen from explosions involving residual propellants or pressurants, battery malfunctions, self-destruction charges, or space defense activities.

Space Debris Facts

IAU Minor Planet Center

IAU Minor Planet Center

IAU Minor Planet Center

Stellar Occultations by Solar System Objects

The IOTA Home Page

http://www.lunar-occultations.com/iota/iotandx.htm

The Occultation Path of 1300 Marcelle

Yale Southern Obs.

The Occultation Path of 203 Pompeja

The Diameter of Juno from its Occultation of AG +0º 1022

The Observations are well represented by a mean elliptical limb profile having semimajor and semiminor axes of 145.2+0.8 and 122.8+1.9 km (Millis, R. et al. 1981, AJ 86, 306)

Light variations of SAO 158687 as it was being

occulted by Uranu’s disk in 1977

The discovery of Uranu’s rings

Jul 03 - Asteroid 496 Gryphia Occults HIP 69127 (6.5 Magnitude Star)

Jul 07 - Jupiter Occults PPM 178840 (10.2 Magnitude Star)

Jul 13 - Moon Occults Jupiter

Jul 14 - Asteroid 253 Mathilde Occults TYC 5684-00949-1 (11.3 Magnitude Star)

Jul 15 - Asteroid 14 Irene Occults HIP 75118 (6.1 Magnitude Star)

Jul 22 - Asteroid 39 Laetitia At Opposition (9.6 Magnitude)

Jul 23 - Asteroid 538 Friederike Occults HIP 88504 (7.5 Magnitude Star)

Jul 29 - Asteroid 1233 Kobresia Occults HIP 18491 (7.5 Magnitude Star)

Occultations Predicted for July 2005

Extrasolar Planetary Systems

The Martir

Filippo (Giordano) Bruno (1548 – 1600)

Bruno affirmed that the universe was homogeneous, made up everywhere of the four elements (water, earth, fire, and air), rather than having the stars be composed of a separate quintessence. Essentially, the same physical laws would operate everywhere in the universe.

Under Bruno’s model, the Sun was simply one more star, and the stars all suns, each with its own planets. Bruno saw a Solar System of a sun/star with planets as the fundamental unit of the universe.

According to Bruno, infinite God necessarily created an infinite universe, formed of an infinite number of solar systems, separated by vast regions full of Aether, because empty space could not exist. (Bruno did not arrive at the concept of a galaxy.)

Each comet is a world, a permanent celestial body, formed of the four elements.

Bruno’s Thoughts

His observations led him to conclude in 1935

that the average separation between the

components of binary stars was about 20 AU,

which is similar to the distance of the gas giants

from the Sun…

Extrapolating from the fact that about 10% of

binaries contained companion stars that were

one-tenth or less as massive as the primaries,

Kuiper suggested there might be 100 billion

planetary systems in our Galaxy alone.

Gerard Peter Kuiper (1905 – 1973)

Searching for Extrasolar Planets

Two Basic Methods

Direct DetectionsIndirect Detections

Indirect Detections

http://exoplanets.org/exoplanets_pub.html

Spectroscopy:Doppler spectroscopy is used to detect the periodic velocity shift of the stellar spectrum caused by an orbiting giant planet.

Transit Photometry:Photometry measures the periodic dimming of the star caused by a planet passing in front of the star along the line of sight from the observer.

Astrometry:Astrometry is used to look for the periodic wobble that a planet induces in the position of its parent star.

The apparent orbit of the Sun around the center of mass of the Solar Systemfrom 1960 to 2025. The tic marks are in intervals of 0.2 mas.

Astrometry

Spectroscopy

Apparent radial velocity of the Sun as it orbits the centrer of mass of the Solar System from 1960 to 2025 as viewed from the vernal

equinox.

Title: Proposal for a project of high-precision stellar radial velocity work Author: Otto Struve Journal: The Observatory, Vol. 72, p. 199-200 (1952) Submission Date: 24 July 1952 Publication Date: October 1952

Transit Photometry

Transit of Venus, June 2004

Second contactJune 8, 2004, 05:39:47.7

UT

Lasne, Belgium

Third contactJune 8, 2004, 11:03:59.8

UT

Lasne, Belgium

Planetary Transit in HD 209458

Artwork by Lynette Cook

Transit in HD 2049458: light variation

Some Results from the University of New South Wales Extrasolar Planets Search

Hidas, M. et al. 2005. MNRAS, 360, 703.

The Future

Darwin will use a flotillaof six space telescopes, each of which will be at least 1.5 metres in diameter. They will work together to scan the nearby Universe, looking for signs of life on Earth-like planets.

At optical wavelengths, a star outshines an Earth-like planet by a billion to one. Partly to alleviate this difficulty, Darwin will observe in the mid-infrared. At these wavelengths, the star-planet contrast drops to a million to one, making detection somewhat more manageable.

Another key reason for observing in the infrared is because life on Earth leaves its mark at these wavelengths.

To see planets around nearby stars would require a telescope of roughly 30 metres in size and this is way beyond the current limits of technology. To overcome this limitation, Darwin will use six telescopes.

Mission facts

Mission factsOBSS is an astrometric satellite designed to determine with unprecedented accuracy the positions, distances, and motions of a billion stars within our galaxy.

OBSS will be optimized for the detection of extrasolar giant planets of 10 Jupiter masses and less, orbiting all Sun-like stars within 300 light-years of the solar system with orbital periods of up to 10 years.

OBSS will detect more than 80 percent of near asteroids with a radius greater than 140 meter. It will also detect hundreds of new Kuiper Belt and trans-Neptunian objects.

OBSS will yield a comprehensive characterization of stars in a volume that will encompass half the Galaxy, including the solar neighborhood and the galactic nucleus.

The OBSS's 1-metre optical telescope would orbit the Sun for five years. It would view each star about 400 times to pinpoint stellar positions to a precision of 100 microarcseconds - 10 times the accuracy of Hipparcos.

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