Sorry, Emily... but this is a hoax. You've been taken in by someone on Godlike Productions who wants to see people run around in a panic.
Originally posted by Emily_Cragg
Sorry, but this object has been observed all over the place.
*************
** EMERGENCY POSTING **
We have made the first unambiguous detection and image of an elusive type of object known as a brown dwarf.

The hoaxer thinks you're stupid enough to think that the minute someone gets confirmation of something dreadful, that they IMMEDIATELY run off to GLP
to post it (and not post it elsewhere.)
GLP does not have a high reputation anywhere because of the number of hoaxers.

The brown dwarf, called Harrington 911A (HA911A), is a small companion to the cool star Sedna

At this point, a quick Googling on "Sedna" would have saved you worry and caused you to have a good laugh at the inane antics of the hoaxer. Sedna
is a planet, and it's a very tiny planet (about the size of our moon.)
Two other facts that you wouldn't have known unless you read up on physics and astronomy: even white dwarf stars are larger than that. Anything as
massive as a star would have a HUGE gravity (keeps the gas in a ball so that fission can occur. Fission how stars burn.)

The brown dwarf, called Harrington 911A (HA911A), is a small companion to the cool star Sedna , located in our solar system today, and making
its passing from the south.

Sedna's in a stable orbit. If this nonexistant "thing" was a "companion to it, then it and Sedna would be in orbit around each other and
following Sedna's orbit around the solar system. Sedna will never, ever, ever ever get close to any of the other planets.
(another note that you wouldn't know about unless you read astronomy: the astronomers would have detected a companion when they found Sedna because
of the "wobble" in Sedna's orbit that the companion caused.)

Estimated to be 20 to 50 times the mass of Jupiter, 911A is too massive and hot to be classified as a planet as we know it, but too small and
cool to shine like a star.

...and as a "companion" to Sedna, it would have ripped the planet apart by tidal forces.

At least 100,000 times dimmer than Earth´s Sun, the brown dwarf is the faintest object ever seen moving through our solar system.

More technical stuff, here. The hoaxer is quoting from papers on brown dwarf stars and is stupidly unaware that something that's VERY dim when it's
far away might NOT be dim when it's close. I can quote the math at you (but won't); however, a brown dwarf star in the sky at the area of
Sedna/Pluto would be brighter than the full moon.
I think we'd see that, don't you?
Cal Tech Scientist
**************

Oh yeah... signing off with "Cal Tech Scientist" just proves that they're a scientist. I think I'll sign off with "famous anonymous pop
singer." That will make any messages I have about the music industry come true, right?

I'm afraid your wishing "NO" will not affects its existence in our solar system.

Then I challenge you to find the object. It's a brown dwarf star... it is glowing more brightly than the full moon and would cast more light than
the full moon on the nights when the Moon isn't visible.
CdrKeenKid has some good resources, and it's helpful to at least glance at those. They will help you recognize when someone on GLP is attempting to
create another hoax and instead of being a victim of StupidScience, you can hop on GLP to point out just how lame the hoaxer is.