Would you trust a denial from the guy who killed Pluto?
Quote from: meekGee on 09/17/2017 04:03 pmWould you trust a denial from the guy who killed Pluto?Somebody recently asked him on there if he was after Mercury next!!!
Quote from: Star One on 09/17/2017 07:04 pmQuote from: meekGee on 09/17/2017 04:03 pmWould you trust a denial from the guy who killed Pluto?Somebody recently asked him on there if he was after Mercury next!!!Funny... And I would respond to the idea, but I know where this would lead...
We haven’t found Planet Nine yet, in case you were wondering. To date, the telescopic searches have really just begun to scratch the surface of the area that needs to be scanned, and, while clever new projects to find Planet Nine with different techniques have been proposed, most of these efforts are just getting underway. But don’t worry: the new season of Subaru searching starts tonight! With good weather, we should be able to scan a significant part of our search area. Stay tuned.To get ready for this new season of searching for Planet Nine, we have spent most of the last year developing our understanding of the way that Planet Nine interacts with the rest of the solar system. Much of this has involved large amounts of analytic and computational work to figure out what the orbit of Planet Nine looks like and where in its orbit Planet Nine is. If we could figure that out perfectly, we could simply go out tonight and point our telescopes right at it, as was done for the discovery of Neptune in 1846. Sadly, we have less information on Planet Nine than Le Verrier did for Neptune in 1846, so we’re not able to pinpoint it just yet, but we are able to constrain what the orbit looks like and, thus, where we should look.
From the Twitter feed it seems like Konstantin Batygin is with him. Not sure how long an individual session on Subaru would be, i.e., if you would have exclusive access the whole time or not.
We report the discovery of a Hr=3.4±0.1 dwarf planet candidate by the Pan-STARRS Outer Solar System Survey. 2010 JO179 is red with (g−r)=0.88±0.21, roughly round, and slowly rotating, with a period of 30.6 hr. Estimates of its albedo imply a diameter of 600--900~km. Observations sampling the span between 2005--2016 provide an exceptionally well-determined orbit for 2010 JO179, with a semi-major axis of 78.307±0.009 au, distant orbits known to this precision are rare. We find that 2010 JO179 librates securely within the 21:5 mean-motion resonance with Neptune on hundred-megayear time scales, joining the small but growing set of known distant dwarf planets on metastable resonant orbits. These imply a substantial trans-Neptunian population that shifts between stability in high-order resonances, the detached population, and the eroding population of the scattering disk.
Q. Any part of the #planetnine story?A. No. 2010 JO179's a=78.3 au orbit is close, compared to what a distant giant planet would influence.
A newly discovered, relatively bright, very likely dwarf planet:A dwarf planet class object in the 21:5 resonance with NeptuneQuoteWe report the discovery of a Hr=3.4±0.1 dwarf planet candidate by the Pan-STARRS Outer Solar System Survey. 2010 JO179 is red with (g−r)=0.88±0.21, roughly round, and slowly rotating, with a period of 30.6 hr. Estimates of its albedo imply a diameter of 600--900~km. Observations sampling the span between 2005--2016 provide an exceptionally well-determined orbit for 2010 JO179, with a semi-major axis of 78.307±0.009 au, distant orbits known to this precision are rare. We find that 2010 JO179 librates securely within the 21:5 mean-motion resonance with Neptune on hundred-megayear time scales, joining the small but growing set of known distant dwarf planets on metastable resonant orbits. These imply a substantial trans-Neptunian population that shifts between stability in high-order resonances, the detached population, and the eroding population of the scattering disk.Michele Bannister (one of the coauthors) tweeted some background https://twitter.com/astrokiwi/status/910158216675373056QuoteQ. Any part of the #planetnine story?A. No. 2010 JO179's a=78.3 au orbit is close, compared to what a distant giant planet would influence.
Quote from: hop on 09/23/2017 09:16 pmA newly discovered, relatively bright, very likely dwarf planet:A dwarf planet class object in the 21:5 resonance with NeptuneQuoteWe report the discovery of a Hr=3.4±0.1 dwarf planet candidate by the Pan-STARRS Outer Solar System Survey. 2010 JO179 is red with (g−r)=0.88±0.21, roughly round, and slowly rotating, with a period of 30.6 hr. Estimates of its albedo imply a diameter of 600--900~km. Observations sampling the span between 2005--2016 provide an exceptionally well-determined orbit for 2010 JO179, with a semi-major axis of 78.307±0.009 au, distant orbits known to this precision are rare. We find that 2010 JO179 librates securely within the 21:5 mean-motion resonance with Neptune on hundred-megayear time scales, joining the small but growing set of known distant dwarf planets on metastable resonant orbits. These imply a substantial trans-Neptunian population that shifts between stability in high-order resonances, the detached population, and the eroding population of the scattering disk.Michele Bannister (one of the coauthors) tweeted some background https://twitter.com/astrokiwi/status/910158216675373056QuoteQ. Any part of the #planetnine story?A. No. 2010 JO179's a=78.3 au orbit is close, compared to what a distant giant planet would influence.Impressive. The upper range of the diameter (which naturally is uncertain for now) would make it comparable to Ceres, and certainly worthy of 'dwarf' status. I doubt we'll actually find a new giant planet (gas or ice), but certainly we could find more worlds like these including perhaps those kin to Pluto and Eris' size and perhaps evidence that'd support the theory of a 5th giant that was ejected.
Origin and Evolution of Short-Period CometsD. Nesvorný et al., 2017Comets are icy objects that orbitally evolve from the trans-Neptunian region (the Kuiper belt and beyond) into the inner Solar System, where they are heated by solar radiation and become active due to sublimation of water ice. Here we perform end-to-end simulations in which cometary reservoirs are formed in the early Solar System and evolved over 4.5 Gyr. The gravitational effects of Planet 9 (P9), hypothesized to circle the Sun on a wide orbit, are included in some of our simulations. Different models are considered for comets to be active, including a simple assumption that comets remain active for Np(q) perihelion passages with perihelion distance q<2.5 au. The orbital distribution and number of active comets produced in our model is compared to observations. The orbital distribution of ecliptic comets (ECs) is well reproduced in models with Np(2.5)=500 and without P9. With P9, the inclination distribution of model ECs is wider than the observed one. We find that the known Halley-type comets (HTCs) have a nearly isotropic inclination distribution (with only a slight preference for prograde orbits). In our model, the HTCs appear to be an extension of the population of returning Oort-cloud comets (OCCs) to shorter orbital periods. The inclination distribution of model HTCs becomes broader with increasing Np, but the existing observational data are not good enough to constrain Np from orbital fits. Np(2.5)>1000 is required to obtain a steady-state population of large active HTCs that is consistent with observations. To fit the ratio of the returning-to-new OCCs, by contrast, our model implies that Np(2.5)<10, possibly because the detected long-period comets are smaller and much easier to disrupt than observed HTCs.
Since the pattern of orbital alignments (of those many "scattered disk" objects) would disappear within a few 10 Ma without P9 (i.e., if it had been ejected early on), chances are it is still out there somewhere. If anyone would ask for reasons to doubt the existence of P9, I'd rather point to articles like this one: https://arxiv.org/abs/1706.07447QuoteOrigin and Evolution of Short-Period CometsD. Nesvorný et al., 2017Comets are icy objects that orbitally evolve from the trans-Neptunian region (the Kuiper belt and beyond) into the inner Solar System, where they are heated by solar radiation and become active due to sublimation of water ice. Here we perform end-to-end simulations in which cometary reservoirs are formed in the early Solar System and evolved over 4.5 Gyr. The gravitational effects of Planet 9 (P9), hypothesized to circle the Sun on a wide orbit, are included in some of our simulations. Different models are considered for comets to be active, including a simple assumption that comets remain active for Np(q) perihelion passages with perihelion distance q<2.5 au. The orbital distribution and number of active comets produced in our model is compared to observations. The orbital distribution of ecliptic comets (ECs) is well reproduced in models with Np(2.5)=500 and without P9. With P9, the inclination distribution of model ECs is wider than the observed one. We find that the known Halley-type comets (HTCs) have a nearly isotropic inclination distribution (with only a slight preference for prograde orbits). In our model, the HTCs appear to be an extension of the population of returning Oort-cloud comets (OCCs) to shorter orbital periods. The inclination distribution of model HTCs becomes broader with increasing Np, but the existing observational data are not good enough to constrain Np from orbital fits. Np(2.5)>1000 is required to obtain a steady-state population of large active HTCs that is consistent with observations. To fit the ratio of the returning-to-new OCCs, by contrast, our model implies that Np(2.5)<10, possibly because the detected long-period comets are smaller and much easier to disrupt than observed HTCs. EDIT: PS: And yes, I also think that we will continue to find dwarf planets in the Kuiper belt for decades to come. Every new generation of telescopes will reveal additional populations. I think its a good bet that there will be many large objects in the Oort cloud, perhaps up to Mars size or more (as this is the typical size of the planetary embryos, of which many had to be ejected early on as the gas giants formed).
Mike Brown @plutokillerNight 4 of Subaru Planet Nine search on Maunakea. We're slowly vacuuming up the sky. My blood O2 level is low, but caffeine level is peaking
Mike Brown @plutokillerCurious where we were looking for Planet Nine last night? Here's the view straight down the Subaru telescope barrel. #NameThatConstellation
Mike Brown @plutokillerNight 5 (of 5) of the Subaru Planet Nine search on Maunakea now underway. Another beautiful night. Tomorrow: home to play with data!
Konstantin Batygin @kbatyginBetween observing runs we hiked up to lake Waiau at 13000ft. @plutokiller got so excited his head fell off. Back on now. P9 search continues
Mike BrownMike Brown @plutokillerTelescope now shuts down for ~2 months of routine maintenance then we're back in December to resume the search. Stay tuned.
Mike Brown @plutokiller(I know 2 months is a long time, but they have to periodically remove the entire mirror from the telescope and realuminize it. Big job.)
I assume the environment degrades it but how often do they have do this?