muahaha...
they have been watching us.... d'oh!
Anything orbiting that fast is also sun synchronous so the temperatures on the dark side might be somewhat tolerable for life.orin stepanek wrote:It is hard to imagine a planet orbiting in 2.2 days. It takes the moon almost a month and it is only a quarter of a million miles from Earth. That planet must be really moving.
Orin
There would probably be a really strong wind carrying heat around from the light side to the dark side, however. The temperature might still be reasonable, but the wind would be.neufer wrote:Anything orbiting that fast is also sun synchronous so the temperatures on the dark side might be somewhat tolerable for life.orin stepanek wrote:It is hard to imagine a planet orbiting in 2.2 days. It takes the moon almost a month and it is only a quarter of a million miles from Earth. That planet must be really moving.
Orin
----------------------------ta152h0 wrote:How do you know if there is only one planet ? and how do you know they are not evenly spread, if so ? pass the beer
How do scientists know if there are more planets around that star, and at which distances they may be orbitting?ta152h0 wrote:i have no idea how ya'll went from what i said to what you are saying
A small close planet like Mercury may have a large enough elliptical orbit that it is ONLY "sun synchronous" during its perihelion phase where the tidal forces are the greatest.Arramon wrote:even with the planet so close, couldn't the rotation still occur? Possibly in reverse, or whatnot. Or would the closeness to a parent star, or a moon to its parent planet, really only cause a sun synchronous orbit.
Right! That would be Hyperion: http://antwrp.gsfc.nasa.gov/apod/ap070128.htmlArramon wrote:So then the proximity of the planet to the sun is just causing it to be whipped around the sun at all times. =)
Making the object keep the same face towards the pull of the sun, like it were tethered as in the video. I've never been on that ride before. =/
A little different than the tilt-a-whirl... =b
You seem to have a problem with the idea of orbits as short as 2.2 daysta152h0 wrote:Is it possible a train of planets transit in the same orbit giving the illusion of only 2.2 days per orbit ?
Code: Select all
_________ Orbital Period in days & inclination
-------------------------------------------------------
1 Neptune III Naiad 0.294 4.7°
2 Neptune IV Thalassa 0.311 0.2°
3 Neptune V Despina 0.335 0.1°
4 Neptune VI Galatea 0.429 0.1°
5 Neptune VII Larissa 0.555 0.2°
6 Neptune VIII Proteus 1.122 0.6°
1 Uranus VI Cordelia 0.335034 0.08479°
2 Uranus VII Ophelia 0.376400 0.1036°
3 Uranus VIII Bianca 0.434579 0.193°
4 Uranus IX Cressida 0.463570 0.006°
5 Uranus X Desdemona 0.473650 0.11125°
6 Uranus XI Juliet 0.493065 0.065°
7 Uranus XII Portia 0.513196 0.059°
8 Uranus XIII Rosalind 0.558460 0.279°
9 Uranus XXVII Cupid 0.618 0.1°
10 Uranus XIV Belinda 0.623527 0.031°
11 Uranus XXV Perdita 0.638 0.0°
12 Uranus XV Puck 0.761833 0.3192°
13 Uranus XXVI Mab 0.923 0.1335°
14 Uranus V Miranda 1.413479 4.232°
15 Uranus I Ariel 2.520379 0.260°
---------------------------------
1 Saturn XVIII Pan +0.57505 0.001° in Encke Division
2 Saturn XXXV Daphnis +0.59408 ≈ 0° in Keeler Gap
3 Saturn XV Atlas +0.60169 0.003° outer A Ring shepherd
4 Saturn XVI Prometheus +0.61299 0.008° inner F Ring shepherd
5 Saturn XVII Pandora +0.62850 0.050° outer F Ring Shepherd
6 Saturn XI Epimetheus +0.69433 0.335° co-orbitals
7 Saturn X Janus +0.69466 0.165° co-orbitals
8 Saturn I Mimas +0.942422 1.566°
9 Saturn XXXII Methone +1.00957 0.007°
10 Saturn XLIX Anthe +1.03650 0.1°
11 Saturn XXXIII Pallene +1.15375 0.181°
12 Saturn II Enceladus +1.370218 0.010° In the thick of E ring
13 Saturn III Tethys +1.887802 0.168°
13a Saturn XIII Telesto leading Tethys trojan
13b Saturn XIV Calypso trailing Tethys trojan
16 Saturn IV Dione +2.736915 0.002°
16a Saturn XII Helene leading Dione trojan
16b Saturn XXXIV Polydeuces trailing Dione trojan
---------------------------------
1 Jupiter XVI Metis +7h 4m 29s 0.06°
2 Jupiter XV Adrastea +7h 9m 30s 0.03°
3 Jupiter V Amalthea +11h 57m 22.67s 0.374°
4 Jupiter XIV Thebe +16h 11m 17s 1.076°
5 Jupiter I Io +1.769137786 0.050°
To a first order, one could consider a single Saturnian ring being a "train of satellites" of roughly equal size in the same orbit. The physics obviously works for very large numbers. Is there a reason why it wouldn't work for much smaller numbers? Or a reason why it wouldn't work for planets around a star? What are the limiting factors?neufer wrote:. . .ta152h0 wrote:Is it possible a train of planets transit in the same orbit giving the illusion of only 2.2 days per orbit ?
none of which involve moons of the same size equally spaced in the same orbit . . .
-----------------------------------Arramon wrote:What about the rotational period of the parent object? Could that cause an orbittal period of a satellite to become altered based on the spin of the parent?
The discovery of a Hot Jupiter exoplanet that transfers orbital momentum to its host star may hold the key to a clearer understanding of the evolution of common planetary systems, according to findings presented today by Dr. Edward Guinan, a professor of astronomy at Villanova University in Villanova, Pa. Guinan announced the find at a press conference held at the opening of the 217th American Astronomy Society meeting in Seattle, Washington. The discovery is of special interest because it represents a rare case in which a research team was able to make an independent age determination of the planet system by studying the system’s faint red dwarf companion star. The discovery opens a new gateway to learning about the dynamics and evolution of many other planetary systems that also contain close-in hot-Jupiter type planets.
HD189733b, the Hot Jupiter exoplanet, orbits an orange (dwarf K) star HD18973A in the constellation Vulpecula (the Fox). It orbits at only three percent of the distance of the Earth from the Sun: i.e. ~0.03 AU) with an orbital period of only 2.2 days (for comparison the Earth takes 365 days to orbit our Sun). The host star is about 63 light-years away and has a mass and diameter about ~80 percent that of our Sun. This star, invigorated by its hot Jupiter planetary companion, appears to have been spun up (rotating ~ >2x faster than our Sun – having a ~12-day rotation period) and is gaining angular momentum from magnetic and tidal interactions with its close-in Jupiter-size planet. The star, however, is being spun-up at the expense of the planet’s orbital angular energy.
The loss in the planet’s orbital momentum in the past may explain why it (and other similar planetary systems) orbit so close to their host stars. While the planet is spiraling in toward the star, and is most likely doomed, there is a possibility that the interacting magnetic fields of the star and planet could create a tidal-magnetically locked orbit rotation that might allow the planet to survive. The most likely scenario, however, is that the planet will draw closer to the star and its atmosphere will be eroded away by the star’s intense radiation and strong winds. The planet will ultimately be ripped apart by the star’s gravity if it survives the star’s radiation and winds.
HD 189733 Ab is a relatively rare eclipsing planetary system that was discovered in 2005 (by Buchy et al.) and has attracted much attention in astronomical circles because it hosts a transiting Hot Jupiter exoplanet. The system is relatively bright (e.g. can be seen with binoculars). The eclipses by the planet permit substantial information to be gained from observing the system inside and outside the planetary eclipses. For example, spectroscopic studies by other teams (e.g. G. Tinnetti et al.) reveal that its hot atmosphere contains water vapor, carbon dioxide, sodium, and, interestingly, organic molecules of methane and particulate haze.
The Villanova team, which includes undergraduates Thomas Santapaga and Ronald Ballouz, found that this system is about over five billion years old and that the Jupiter-size planet has been estimated to be very hot at ~1,500 degrees Fahrenheit by other researchers. HD189733b has one of the shortest known orbital periods of only P = 2.22 days and is only 0.031AU from its host star (i.e. only ~8.75x the radius of the host star). The exoplanet system includes a cool red dwarf companion star (HD 189733B). This faint companion star is located at ~12” distance to the K-dwarf. At the distance of HD 189733 this corresponds to a separation of ~220 AU/ For comparison this 220x the distance of the Earth from the Sun / or over 5.5x further than the distance of Pluto from the Sun.) The presence of this red dwarf star makes a reliable age estimate of the binary system possible via activity-age relations developed at Villanova.
“Planetary systems like HD 189733 with short period, “hot-Jupiter” planets are very common – over a hundred have been discovered so far,” Guinan noted. He continued, “HD 189733 and dozens of other planetary systems like it, many of which were recently discovered by NASA’s Kepler mission, may also be undergoing the same process of strong magnetic interactions between their close-in large planets and their host stars.”
“The big clue that is different here is that we know the age of HD 189733 from the study of its coeval faint companion star.” This discovery should help in our endeavors to try to better understand the dynamics of other planetary systems like HD 189733, he added.”
Of the over 500 exoplanets that have been discovered to date, HD 189733 is the only one of a handful whose age and physical properties have been well determined.
“This study may help explain how and why hot Jupiters form and evolve. It may help explain this whole class of planets,” Guinan remarked.
In conducting this study the research team, which includes Villanovans Thomas Santapaga, Ronald L. Ballouz, Scott E. Engle, Laurence E. DeWarf, along with Styliani (Stella) Kafka from the Carnegie Institute in Washington, D.C.’s Department of Terrestrial Magnetism, observed the exoplanet system using the Clay Telescope at the Carnegie Institution of Washington’s Las Campanas Observatory in Chile. Observations of the eclipse timings of HD 189733 continue at Villanova using the Four College Automatic Photoelectric Telescope (FCAPT) located in southern Arizona. The eclipse timings made with this telescope over time could provide evidence that the orbital period of the system is indeed decreasing.
The research project is funded through The National Science Foundation‘s Research at Undergraduate Institutions and grants from NASA.
Guinan’s Jan. 10 presentation of the team’s findings at the 217th AAS Meeting are from a paper titled, “Some Like It Hot” – Evidence for the Shrinking Orbit of the 2.2-day Transiting Hot Jupiter Exoplanet HD 189733b – Evidence of Transfer of Planet Orbital Momentum to its Host Star” (AAS 217th Meeting Abstract 343.12, P. 566).
“One of the most amazing results of our team’s research is that a planet-size body that is only 1/1000x times the mass of the host star can make such a large impact by magnetically interacting with its host star to the extent that it causes the star to spin up, activating a strong magnetic dynamo of the star that produces the observed strong X-ray coronal emissions, large starspots and other phenomena,” Guinan concluded.