The "Kuiper Cliff"

[V-GER]

Same reason we've got 50 year old pictures of Sedna and only realized what it was recently.

Its easy to find something when you know where to look.

True, but still, a brown dwarf?

[Doodler]

True, but still, a brown dwarf?

Until REAL recently, we didn't know a brown dwarf from a hole in the ground. Nice and solid theoretical objects without a heck of a lot of observation to back'em up.

Also remember that until very recently, searchers were pretty obsessed with the Solar System's ecliptic plane. If what we're looking for has an orbit akimbo enough to be clear of the ecliptic, then its not impossible that our searches have quite simply been in the wrong place.

That a survey was done is all well and good, but lets face it, every time they go back and do another survey, the find more stuff they missed previously. Now that the Kuiper belt has gotten us over the misconception that objects should be orbiting somewhere near the Sun's equatorial plane, we can start looking in places we might not have considered before, and maybe we have seen it, we just haven't recongnized it for what it is. If it was off the ecliptic, it could have been confused for a distant background object and the significance overlooked. Extremely low proper motion does throw us a curve every once in a not-so-great while.

[Nereid]

Hard to understand how RECONS could have missed a brown dwarf as close as some here have suggested ...

[V-GER]

We might well find an "Earth on steroids" out there but I just can't see how we could have missed a failed star, with a mass many times that of Jupiter within a light year of the Sun(since it's supposed to be one half of a binary, I wouldn't expect it to be much further.)

[Eckelston]

Hard to understand how RECONS could have missed a brown dwarf as close as some here have suggested ...

I wonder if RECONS even capable of finding objects that are very close. I mean if they image the same part of the sky every month or couple of weeks even then a brown dwarf 10000 AU away won't show up. The parallax will be just too high to recognize that you are looking at the same object in different pictures. Well, that's just my guess, maybe you can try to fit ellipses on objects of the same magnitude but you might just end up with a bunch of false positives.

[Nereid]

I wonder if RECONS even capable of finding objects that are very close. I mean if they image the same part of the sky every month or couple of weeks even then a brown dwarf 10000 AU away won't show up. The parallax will be just too high to recognize that you are looking at the same object in different pictures. Well, that's just my guess, maybe you can try to fit ellipses on objects of the same magnitude but you might just end up with a bunch of false positives.

There are (at least) three considerations:

* magnitude (in the bands RECONS is looking in) - how far away would a brown dwarf be, to be just detectable at the faint limit (d_RECONS)? how close would a brown dwarf be, to have been included in the HIPPARCOS input catalogue (d_HIP)?

* parallax - what is the parallax of an object between d_HIP and d_RECONS?

* proper motion - what would the typical proper motion of an object be, in a circular orbit around the Sun, with radius d_HIP and radius d_RECONS?

These aren't very hard limits on the parameter space, but should be enough to give some pointers to the likelihood that a brown dwarf could be lurking, undetected ...

[Blob]

Size distribution of circumstellar disks in the Trapezium cluster
Authors: S. Vicente (1 and 2), J. Alves (1) ((1) ESO, Germany, (2) FCUL, Lisboa, Portugal)

In this paper the researchers present results on the size distribution of circumstellar disks in the Trapezium cluster as measured from Hubble Space Telescope WFPC2 data.

Direct diameter measurements of a sample of 135 bright proplyds and 14 silhouettes disks suggest that there is a single population of disks well characterized by a power-law distribution with an exponent of -1.9 +- 0.3 between disk diameters 100-400 AU. For the stellar mass sampled (from late G to late M stars) they find no obvious correlation between disk diameter and stellar mass.
They also find that there is no obvious correlation between disk diameter and the projected distance to the ionizing Trapezium OB stars.

The researchers estimate that about 40% of the disks in the Trapezium have radius larger than 50 AU, and suggest that the origin of the Solar system's (Kuiper belt) outer edge is likely to be due to the star formation environment and disk destruction processes (photoevaporation, collisions) present in the stellar cluster on which the Sun was probably formed.

Finally, they identified a previously unknown proplyd and named it 266-557, following convention.

Images (PDF)
Read More (PDF)

[transreality]

Could interactions between the terminal shock boundary and kuiper belt objects clear them from the area?

[RalofTyr]

Why does Tau Ceti have such a large Oort/Kuiper cloud/belt? It is ten times more massive than our own. With this in mind, perhaps in the 4.5 billion years the sol system as been around, another star or massive object distrupted the Kuiper belt causing the remove of matter. Or perhap causing some of that material to fall into the Earth orbit to give us are vast oceans?

[A.DIM]

The RECONS site states, in the "100 Nearest..." list, that only 12 of those 100 have been accurately measured, so I'm still unconvinced it would have found it.
And if we have, and there's no CT, it must be miscatalogued or misidentified.

But I think the perturber is in an elliptical orbit, perhaps varied and changeable, and inclined to the ecliptic considerably, some 20-30deg. I think it will have several satellites, of which perhaps only a larger outer body is our hypothetical perturber responsible for the "cliff" or gap.

[Doodler]

The RECONS site states, in the "100 Nearest..." list, that only 12 of those 100 have been accurately measured, so I'm still unconvinced it would have found it.
And if we have, and there's no CT, it must be miscatalogued or misidentified.

But I think the perturber is in an elliptical orbit, perhaps varied and changeable, and inclined to the ecliptic considerably, some 20-30deg. I think it will have several satellites, of which perhaps only a larger outer body is our hypothetical perturber responsible for the "cliff" or gap.

If its an object of substantial mass, how could its orbit remain unstable after so long? Pushing a planet out of its orbit entails a massive amount of energy...even for a dinky little thing like the Moon.

Are you sure this is a likely situation?

[Blob]

Hum,
it is very unlikely.

http://www.bautforum.com/showthread.php?t=14571&page=3

[A.DIM]

If its an object of substantial mass, how could its orbit remain unstable after so long? Pushing a planet out of its orbit entails a massive amount of energy...even for a dinky little thing like the Moon.

Are you sure this is a likely situation?

I am sure of nothing regarding such an hypothesis as this.

[A.DIM]

Hum,
it is very unlikely.

http://www.bautforum.com/showthread.php?t=14571&page=3

Sorry, I'm unsure what in that thread is so illuminating?

[Blob]

Hum,
I was just pointing out the thread in general.

But the main points i found were that pulsar timing studies excluded a small companion within 300-400 AU.
And if it is further away, there is a question whether it would have survived the close passages of stars in the past.
It would presumably have to be very lucky or large to survive those encounters; and if it were so large then it seems likely that it would have been seen in the infrared or optical surveys, and identified by the redshift.
But, the most compelling evidence, for me, is the existence and orbit of Sedna, (ie the orbit would have been perturbed by now).

And knowing what we already know about the early solar system nursery, and the galactic orbit of the sun to explain the extinction events etc, then there is really no need to invent a solar companion, (er - unless we want to sell a book about it)

[Nereid]

The RECONS site states, in the "100 Nearest..." list, that only 12 of those 100 have been accurately measured, so I'm still unconvinced it would have found it.
And if we have, and there's no CT, it must be miscatalogued or misidentified.

But I think the perturber is in an elliptical orbit, perhaps varied and changeable, and inclined to the ecliptic considerably, some 20-30deg. I think it will have several satellites, of which perhaps only a larger outer body is our hypothetical perturber responsible for the "cliff" or gap.

Time to dust off our calculators perhaps?

We could start with 'what's the closest distance a brown dwarf could be, to have just avoided being included in the HIPPARCOS input catalogue?'

Note that this assumes all stars down to a (visual) mag of ~12 have been catalogued.

So, what's a reasonable absolute (visual) magnitude for a brown dwarf? It doesn't have to be too precise ...

[Blob]

Hum,
there are some handy figures that have already been worked out here...

Title: Mass Limit on Nemesis
Authors: Varun Bhalerao (1), M. N. Vahia (2) ((1) Indian Institute of Technology Bombay, (2) TIFR)

We assume that if the sun has a companion, it has a period of 27 Myr corresponding to the periodicity seen in cometary impacts on earth. Based on this assumption, it is seen that the inner Lagrengian point of the interaction between the Sun and its companion is in the Oort cloud. From this we calculate the mass -- distance relation for the companion. We then compute the expected apparent magnitude (visible and J band) for the companion using the models of Burrows (1993). We then compare this with the catalogue completeness of optical and infrared catalogues to show that the sun cannot have a companion of mass greater than 44 M_jup (0.042 M_sun)

Read more (67kb, PDF)

[A.DIM]

Time to dust off our calculators perhaps?

We could start with 'what's the closest distance a brown dwarf could be, to have just avoided being included in the HIPPARCOS input catalogue?'

Note that this assumes all stars down to a (visual) mag of ~12 have been catalogued.

So, what's a reasonable absolute (visual) magnitude for a brown dwarf? It doesn't have to be too precise ...

Hi Nereid.

Let's say 19 to 22 although I'm unconvinced by the assumption that all stars down to ~12 have been catalogued, for various reasons stated previously.


But what do you think is the cause of the so called "cliff?"

[Foriiiiz]

Ok, don t know about all this heady stuff. Just know, I am interested and via this forum, wish to become enlightened. In regards to kwiper cliff: is it possible that this seemingly void of any cosmic junk...it could be like the bodies of water In that, they are divided by brackish waters and so, the same with the cliff as we low it. There are seven such worlds like our own and this area separates us from them?...I think Einstein was onto something when he said that space is very like fabric folded in and upon itself in an accordion pattern and, by punching a hole in the fabric of space, we can time travel.

[publiusr]

You guys certainly have forgotten more than I would ever hope to learn on the subject--but what if Gilese 710/ DM 61 366 which was supposed to make a return--was misidentified as a star farther out and thus is the companion/nemesis everyone has been looking for?

[kzb]

WISE should have found anything from small brown dwarf mass upwards. There is also a recent paper (Matiese et al ??) where they have searched the WISE data for massive planets in the orbital space they expect from putative cometary orbit disruption. They didn't find one.

WISE should be able to detect a Jupiter to about 1 light year distance. But I don't think the data mining to date would have found it, if it existed. They've only searched for BD's so far.

But I've got to say, this object is fast running out of parameter space in which to hide. I think it is already constrained to something like four times Jupiter mass or it would've been found already. Disappointing I know, but my money is on no further massive planets in orbit around our sun.

This does not preclude rogue planets, in fact there is evidence (Sumi et al) that there are plenty of these. There is also a theoretical basis for expecting unbound planets to be plentiful, because stellar system formation models show that many planets get ejected from their home systems in the early days after its formation.

[Jerry]

It is not unusual for a prediction for where planetary masses are to fail. If the 'dwarf planet' count is not increased by a factor of three or more, expect the 'dwarf' term to drop.

I think it can be said that a companion brown dwarf would have to be much cooler than expected; and likewise for most dwarfs we might have missed. Missing on the temperature, composition and mass of planets and comets is common.