7604 Kridsadaporn
Encyclopedia
7604 Kridsadaporn is a Mars-crossing asteroid discovered by R. H. McNaught
on 31 August 1995 at Siding Spring Observatory
near the town of Coonabarabran
, Australia
. Kridsadaporn's high orbital eccentricity
of just over 0.574 places it within a group of objects known as Asteroids in Cometary Orbit (ACOs). Due to its unusual orbital parameters
, Kridsadaporn is listed by the IAU Minor Planets Center
as an Unusual Minor Planet.
, as part of the Siding Spring Survey
(SSS), which itself is part of a broader network of Near-Earth object
search programs.
The then-unnamed asteroid was initially assigned the provisional designation
1995 QY2. In April 2005 it was renamed by its discoverer (Robert McNaught) in honour of Kridsadaporn Ritsmitchai, a then recently deceased friend and colleague
at the Research School of Astronomy and Astrophysics at the Australian National University
, who worked and resided at Siding Spring Observatory.
Kridsadaporn (กฤษฏาพร krìsàtāːpʰōn, กฤษดาพร krìsàdāːpʰōn) is a Thai name comprising two words: "kridsada" (กฤษฏา) of Sanskrit origin, meaning "supernatural powers, divine, celestial"; and "porn" (พร) meaning "blessing, benediction, favour". Often Thai first names are suffixed with "porn" (พร) denoting, "a blessing from the Buddha
", referring to both the gift of a child, and the favour of particular attributes, referred to within the name, manifesting within the child. In Thai tradition, a child's name is chosen using complex Buddhist name giving rituals where Thai astrology is widely used, often in consultation with a Buddhist monk.
Parents of a newly-born child named Kridsadaporn (กฤษฏาพร) may believe, or may accept, the name's meaning as, "a blessing from the Buddha; a child, gifted with divine qualities and supernatural powers".
(T) is applied to cometary encounters with planets (such as Jupiter
) and used to describe their orbital inter-relationship.
Asteroidal-appearing bodies in elliptical orbits with Jovian
Tisserand parameters Tj < 3 only began to appear in search programs in the mid 1980’s - Kridsadaporn's Jovian Tisserand parameter is Tj = 2.858. Before this, the failure to identify these objects was used as an argument against the existence of extinct cometary nuclei. Over the past two decades, an increasing number of asteroids, based upon their orbital and physical characteristics, have been suggested as extinct or dormant comets candidates. It is now considered likely that within the asteroid population there exist a significant number of dormant or extinct comets.
More recently, Kridsadaporn has received closer attention after having been included in a number of studies relating to the analysis of spectral
properties of asteroids in cometary orbits (ACOs);
and, collisional activation processes, and the dynamic and physical properties of ACOs. The investigation of ACOs is considered important in the understanding of formation processes of cometary dust mantles and the end states of comets, so as to determine the population of Jupiter family comets
(JFCs), and, to also understand the dynamical processes involved in the transport mechanism of asteroids from typical asteroidal orbits to cometary-like ones.
In earlier studies, ACOs have sometimes been referred to as cometary asteroids or comet-asteroid transition objects.
as fragments injected into a mean-motion resonance
or secular resonance
, developing increasingly higher orbital eccentricity over time resulting in the perihelion distance becoming smaller than the aphelion distances of the inner planets. At their birth, near-earth asteroids (NEAs) and MC orbits are in resonance, and when their orbital eccentricity becomes large enough, to the point that their orbits cross those of the inner planets, their orbits then become modified in a random-walk fashion
. This results in a complex interplay between planetary encounters and resonances which may lead to a range of unexpected outcomes including cometary-type orbits; solar collisions; or, eventual ejection from the Solar System
.
The histogram of asteroid semi-major axis
has several prominent dips in the distribution. These gaps are more sparingly populated with objects of higher orbital eccentricity. Known as Kirkwood gaps, these dips in distribution density correspond to the location of orbital resonances with Jupiter. Objects with eccentric orbits continue to increase in orbital eccentricity over longer time-scales to eventually break out of resonance due to close encounters with a major planet.
Kridsadaporn, with a semi-major axis of e = 3.110626, corresponds to a very narrow gap associated with the 11:7 resonance within a series of weaker and less sculpted gaps.
classification typified as dark carbonaceous
objects.
A number of studies included Kridsadaporn within a sample of asteroids in cometary orbits in order to understand the relationships in spectral
characteristics between ACOs, the Jupiter-family comets, and the outer main belt asteroids. The only finding was that comets present neutral or red feature-less spectra. Earlier studies
suggested that comets in all stages of evolution - active; dormant; and, dead - were very dark, often reddish, objects with spectra similar to D-type
, P-type
and C-type asteroids
of the outer Solar System with probably carbonaceous dust containing reddish organic compounds
controlling their colour and albedo
characteristics.
found in general that they exhibit lower albedos than objects with Tj > 3 and further concluded that all ACOs in that sample with Tj < 2.6 had albedos pV < 0.075 - similar to those measured for cometary nuclei - suggesting cometary origins.
A sample of objects, which included Kridsadaporn, was used in a study of the relationship between the Jovian Tisserand invariant and spectral properties of asteroids in cometary orbits, which determined that all observed ACOs within the sample with Tj < 2.9 were feature-less. Kridsadaporn, with its Jovian Tisserand invariant of 2.858, falls within the feature-less (without bands) comet-like spectral group. These studies also concluded that ACOs with featured spectra (with bands) typical of the main belt had Tj ≥ 2.9 while those with Tj < 2.9 demonstrated comet-like spectra, suggesting that the subsample of ACOs with 2.9 ≤ Tj ≤ 3.0 could be populated by a large fraction of interlopers from the inner part of the belt.
Kridsadaporn has a perihelion distance q = 1.3224 AU
.
A study of the relationship between the size distribution profile and perihelion distances of ACOs
concluded that a sub-sample of ACOs with a perihelion distance q > 1.3 AU
had a size distribution profile similar to that of the Jupiter family comets, suggesting that sub-sample to be composed of a significant fraction of dormant comets, while a large fraction of ACOs with q < 1.3 AU
could more likely be scattered objects from the outer main belt.
Objects with a Jovian Tisserand invariant Tj ≤ 3 and taxonomic properties consistent with a low albedo, however, are not enough to imply that they are dormant or extinct comets. The fraction of low albedo, Tj ≤ 3, objects actually being dormant or extinct comets is estimated to be 65% ± 10%.
Robert H. McNaught
Robert H. McNaught is a Scottish-Australian astronomer at the Research School of Astronomy and Astrophysics of the Australian National University. He has collaborated with David J. Asher of the Armagh Observatory....
on 31 August 1995 at Siding Spring Observatory
Siding Spring Observatory
Siding Spring Observatory near Coonabarabran, New South Wales, Australia, part of the Research School of Astronomy & Astrophysics at the Australian National University , incorporates the Anglo-Australian Telescope along with a collection of other telescopes owned by the Australian National...
near the town of Coonabarabran
Coonabarabran, New South Wales
Coonabarabran is a town in Warrumbungle Shire in northern New South Wales, Australia. At the 2006 census, the town had a population of 2,609.-History and description:...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. Kridsadaporn's high orbital eccentricity
Orbital eccentricity
The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...
of just over 0.574 places it within a group of objects known as Asteroids in Cometary Orbit (ACOs). Due to its unusual orbital parameters
Orbital elements
Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are generally considered in classical two-body systems, where a Kepler orbit is used...
, Kridsadaporn is listed by the IAU Minor Planets Center
Minor Planet Center
The Minor Planet Center operates at the Smithsonian Astrophysical Observatory , which is part of the Center for Astrophysics along with the Harvard College Observatory ....
as an Unusual Minor Planet.
Discovery and naming
Kridsadaporn was discovered using the 0.5-m Uppsala Schmidt TelescopeUppsala Southern Schmidt Telescope
The Uppsala Schmidt Telescope was moved to Siding Spring Observatory from Mount Stromlo Observatory in 1980. Has field of view three times as large as the Anglo-Australian Telescope. Uses a spherical not parabolic mirror with 0.6m correcting plate to achieve this. Photographic plates and film used...
, as part of the Siding Spring Survey
Siding Spring Survey
The Siding Spring Survey is a Near-Earth object search program that uses the 0.5-m Uppsala Schmidt Telescope at Siding Spring Observatory, New South Wales, Australia. It is the southern hemisphere counterpart of the Catalina Sky Survey located in the Santa Catalina Mountains on Mt Bigelow, near...
(SSS), which itself is part of a broader network of Near-Earth object
Near-Earth object
A near-Earth object is a Solar System object whose orbit brings it into close proximity with the Earth. All NEOs have a perihelion distance less than 1.3 AU. They include a few thousand near-Earth asteroids , near-Earth comets, a number of solar-orbiting spacecraft, and meteoroids large enough to...
search programs.
The then-unnamed asteroid was initially assigned the provisional designation
Provisional designation in astronomy
Provisional designation in astronomy is the naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calculated...
1995 QY2. In April 2005 it was renamed by its discoverer (Robert McNaught) in honour of Kridsadaporn Ritsmitchai, a then recently deceased friend and colleague
at the Research School of Astronomy and Astrophysics at the Australian National University
Australian National University
The Australian National University is a teaching and research university located in the Australian capital, Canberra.As of 2009, the ANU employs 3,945 administrative staff who teach approximately 10,000 undergraduates, and 7,500 postgraduate students...
, who worked and resided at Siding Spring Observatory.
Kridsadaporn (กฤษฏาพร krìsàtāːpʰōn, กฤษดาพร krìsàdāːpʰōn) is a Thai name comprising two words: "kridsada" (กฤษฏา) of Sanskrit origin, meaning "supernatural powers, divine, celestial"; and "porn" (พร) meaning "blessing, benediction, favour". Often Thai first names are suffixed with "porn" (พร) denoting, "a blessing from the Buddha
Gautama Buddha
Siddhārtha Gautama was a spiritual teacher from the Indian subcontinent, on whose teachings Buddhism was founded. In most Buddhist traditions, he is regarded as the Supreme Buddha Siddhārtha Gautama (Sanskrit: सिद्धार्थ गौतम; Pali: Siddhattha Gotama) was a spiritual teacher from the Indian...
", referring to both the gift of a child, and the favour of particular attributes, referred to within the name, manifesting within the child. In Thai tradition, a child's name is chosen using complex Buddhist name giving rituals where Thai astrology is widely used, often in consultation with a Buddhist monk.
Parents of a newly-born child named Kridsadaporn (กฤษฏาพร) may believe, or may accept, the name's meaning as, "a blessing from the Buddha; a child, gifted with divine qualities and supernatural powers".
Context
An approximation known as the Tisserand criteriaTisserand's parameter
Tisserand's parameter is a combination of orbital elements used in a restricted three-body problem.-Definition:...
(T) is applied to cometary encounters with planets (such as Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
) and used to describe their orbital inter-relationship.
Asteroidal-appearing bodies in elliptical orbits with Jovian
Jovian
Jovian , was Roman Emperor from 363 to 364. Upon the death of emperor Julian during his campaign against the Sassanid Persians, Jovian was hastily declared emperor by his soldiers...
Tisserand parameters Tj < 3 only began to appear in search programs in the mid 1980’s - Kridsadaporn's Jovian Tisserand parameter is Tj = 2.858. Before this, the failure to identify these objects was used as an argument against the existence of extinct cometary nuclei. Over the past two decades, an increasing number of asteroids, based upon their orbital and physical characteristics, have been suggested as extinct or dormant comets candidates. It is now considered likely that within the asteroid population there exist a significant number of dormant or extinct comets.
More recently, Kridsadaporn has received closer attention after having been included in a number of studies relating to the analysis of spectral
Spectral line
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from a deficiency or excess of photons in a narrow frequency range, compared with the nearby frequencies.- Types of line spectra :...
properties of asteroids in cometary orbits (ACOs);
and, collisional activation processes, and the dynamic and physical properties of ACOs. The investigation of ACOs is considered important in the understanding of formation processes of cometary dust mantles and the end states of comets, so as to determine the population of Jupiter family comets
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
(JFCs), and, to also understand the dynamical processes involved in the transport mechanism of asteroids from typical asteroidal orbits to cometary-like ones.
In earlier studies, ACOs have sometimes been referred to as cometary asteroids or comet-asteroid transition objects.
Orbit
Kridsadaporn's highly elliptical orbit has similar orbital characteristics to those of the Jupiter-family comets (JFCs) which populate the Jovian Tisserand invariant range 2 ≤ Tj ≤ 3, which supports the scenario that a significant number of asteroids in cometary orbits are extinct or dormant cometary candidates.Mars-crossing orbit
Kridsadaporn is amongst another group of bodies [Mars-crossing (MC) and/or near-Earth object (NEO) populations] that may have originated from the main asteroid beltAsteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...
as fragments injected into a mean-motion resonance
Mean motion
Mean motion, n\,\!, is a measure of how fast a satellite progresses around its elliptical orbit. Unless the orbit is circular, the mean motion is only an average value, and does not represent the instantaneous angular rate....
or secular resonance
Secular resonance
A secular resonance is a type of orbital resonance.Secular resonances occur when the precession of two orbits is synchronised . A small body in secular resonance with a much larger one will precess at the same rate as the large body...
, developing increasingly higher orbital eccentricity over time resulting in the perihelion distance becoming smaller than the aphelion distances of the inner planets. At their birth, near-earth asteroids (NEAs) and MC orbits are in resonance, and when their orbital eccentricity becomes large enough, to the point that their orbits cross those of the inner planets, their orbits then become modified in a random-walk fashion
Random walk
A random walk, sometimes denoted RW, is a mathematical formalisation of a trajectory that consists of taking successive random steps. For example, the path traced by a molecule as it travels in a liquid or a gas, the search path of a foraging animal, the price of a fluctuating stock and the...
. This results in a complex interplay between planetary encounters and resonances which may lead to a range of unexpected outcomes including cometary-type orbits; solar collisions; or, eventual ejection from the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
.
Orbital evolution
Detailed investigations into Kridsadaporn’s dynamic evolution have been carried out by creating 15 "clone" orbits, integrated forward over a period of 1.2 × 106 years, by changing the last digit of its orbital parameters. Nine (9) clones demonstrated moderate chaotic behaviour jumping between the Jovian mean-motion resonances of 15:7, 9:4, and 11:5 with some orbits becoming Earth-crossers within the integration period. The remaining six (6) clones grew in orbital eccentricity until becoming Jupiter-crossers, and then, behaving as Jupiter-family comets, they were ejected from the Solar System over periods in the order of 105 years.The histogram of asteroid semi-major axis
Semi-major axis
The major axis of an ellipse is its longest diameter, a line that runs through the centre and both foci, its ends being at the widest points of the shape...
has several prominent dips in the distribution. These gaps are more sparingly populated with objects of higher orbital eccentricity. Known as Kirkwood gaps, these dips in distribution density correspond to the location of orbital resonances with Jupiter. Objects with eccentric orbits continue to increase in orbital eccentricity over longer time-scales to eventually break out of resonance due to close encounters with a major planet.
Kridsadaporn, with a semi-major axis of e = 3.110626, corresponds to a very narrow gap associated with the 11:7 resonance within a series of weaker and less sculpted gaps.
Physical characteristics
Kridsadaporn is of a C-type taxonomicTaxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
classification typified as dark carbonaceous
Carbonaceous
Carbonaceous is the defining attribute of a substance rich in carbon. Particularly, carbonaceous hydrocarbons are very unsaturated, high-molecular-weight hydrocarbons, having an elevated carbon:hydrogen ratio....
objects.
A number of studies included Kridsadaporn within a sample of asteroids in cometary orbits in order to understand the relationships in spectral
Spectral line
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from a deficiency or excess of photons in a narrow frequency range, compared with the nearby frequencies.- Types of line spectra :...
characteristics between ACOs, the Jupiter-family comets, and the outer main belt asteroids. The only finding was that comets present neutral or red feature-less spectra. Earlier studies
suggested that comets in all stages of evolution - active; dormant; and, dead - were very dark, often reddish, objects with spectra similar to D-type
D-type asteroid
D-type asteroids have a very low albedo and a featureless reddish electromagnetic spectrum. It has been suggested that they have a composition of organic rich silicates, carbon and anhydrous silicates, possibly with water ice in their interiors...
, P-type
P-type asteroid
P-type asteroids have low albedo and a featureless reddish electromagnetic spectrum. It has been suggested that they have a composition of organic rich silicates, carbon and anhydrous silicates, possibly with water ice in their interior...
and C-type asteroids
C-type asteroid
C-type asteroids are carbonaceous asteroids. They are the most common variety, forming around 75% of known asteroids, and an even higher percentage in the outer part of the asteroid belt beyond 2.7 AU, which is dominated by this asteroid type...
of the outer Solar System with probably carbonaceous dust containing reddish organic compounds
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
controlling their colour and albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
characteristics.
Origins of ACO objects
Studies analysing the albedo distribution of a sample of asteroids in cometary orbits,found in general that they exhibit lower albedos than objects with Tj > 3 and further concluded that all ACOs in that sample with Tj < 2.6 had albedos pV < 0.075 - similar to those measured for cometary nuclei - suggesting cometary origins.
A sample of objects, which included Kridsadaporn, was used in a study of the relationship between the Jovian Tisserand invariant and spectral properties of asteroids in cometary orbits, which determined that all observed ACOs within the sample with Tj < 2.9 were feature-less. Kridsadaporn, with its Jovian Tisserand invariant of 2.858, falls within the feature-less (without bands) comet-like spectral group. These studies also concluded that ACOs with featured spectra (with bands) typical of the main belt had Tj ≥ 2.9 while those with Tj < 2.9 demonstrated comet-like spectra, suggesting that the subsample of ACOs with 2.9 ≤ Tj ≤ 3.0 could be populated by a large fraction of interlopers from the inner part of the belt.
Kridsadaporn has a perihelion distance q = 1.3224 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
.
A study of the relationship between the size distribution profile and perihelion distances of ACOs
concluded that a sub-sample of ACOs with a perihelion distance q > 1.3 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
had a size distribution profile similar to that of the Jupiter family comets, suggesting that sub-sample to be composed of a significant fraction of dormant comets, while a large fraction of ACOs with q < 1.3 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
could more likely be scattered objects from the outer main belt.
Objects with a Jovian Tisserand invariant Tj ≤ 3 and taxonomic properties consistent with a low albedo, however, are not enough to imply that they are dormant or extinct comets. The fraction of low albedo, Tj ≤ 3, objects actually being dormant or extinct comets is estimated to be 65% ± 10%.