HD 106906 b

Promising find to confirm young exoplanets in proplyds.
 
HD 106906 b: A planetary-mass companion outside a massive debris disk
 

Quote :

We report the discovery of a planetary-mass companion, HD 106906 b, with the new Magellan Adaptive Optics (MagAO) + Clio2 system. The companion is detected with Clio2 in three bands: $J$, $K_S$, and $L^\prime$, and lies at a projected separation of 7.1'' (650 AU). It is confirmed to be comoving with its $13\pm2$ Myr-old F5 host using Hubble Space Telescope/Advanced Camera for Surveys astrometry over a time baseline of 8.3 yr. DUSTY and COND evolutionary models predict the companion's luminosity corresponds to a mass of $11\pm2 M_{Jup}$, making it one of the most widely separated planetary-mass companions known. We classify its Magellan/Folded-Port InfraRed Echellette $J/H/K$ spectrum as L$2.5\pm1$; the triangular $H$-band morphology suggests an intermediate surface gravity. HD 106906 A, a pre-main-sequence Lower Centaurus Crux member, was initially targeted because it hosts a massive debris disk detected via infrared excess emission in unresolved Spitzer imaging and spectroscopy. The disk emission is best fit by a single component at 95 K, corresponding to an inner edge of 15-20 AU and an outer edge of up to 120 AU. If the companion is on an eccentric ($e>0.65$) orbit, it could be interacting with the outer edge of the disk. Close-in, planet-like formation followed by scattering to the current location would likely disrupt the disk and is disfavored. Furthermore, we find no additional companions, though we could detect similar-mass objects at projected separations $>35$ AU. In situ formation in a binary-star-like process is more probable, although the companion-to-primary mass ratio, at $<1\%$, is unusually small.

What a weird object - this has the potential to mess up the formation theories even more!

Link about the discovery (Univ. Of Arizona)

https://visao.as.arizona.edu/press/magao-discovers-a-planet/

If the object forms in the same way brown dwarfs form, is this object really so difficult to explain?

myuk myuk sirius short-sighted myuk myuk

Quote :

In situ formation in a binary-star-like process is more probable, although the companion-to-primary mass ratio, at <1%, is unusually small.

Wide-separation brown dwarfs are already difficult to explain, so increasing the mass ratio just makes things more confusing (and, to some extent, formation-ambiguous).

... f**k. I hate Dr. Who.
https://www.change.org/petitions/international-astronomical-union-to-rename-the-newly-discovered-planet-hd-106906-b-to-gallifrey-in-honour-of-doctor-who-and-its-50-years-gallifreyfound

According to IAU rules no curent age/epoch characters or persons should be proposed for naming.

Personally I would propose "Ostro", after XV Century name for Crux sky field (with Ostro meaning "Austral"). Somewhat a cultural reference.

Everything but Doctor Who!   

Doctor Who's fine as long as you don't take it too seriously.

Makes a change from the usual proposals of things from Star Wars anyway.

SPHERE & GPI : the race !

http://arxiv.org/abs/1510.02511

A narrow, edge-on disk resolved around HD 106906 with SPHERE

HD~106906AB is so far the only young binary system around which a planet has been imaged and a debris disk evidenced thanks to a strong IR excess. As such, it represents a unique opportunity to study the dynamics of young planetary systems. We aim at further investigating the close (tens of au scales) environment of the HD~106906AB system. We used the extreme AO fed, high contrast imager SPHERE recently installed on the VLT to observe HD~106906. Both the IRDIS imager and the Integral Field Spectrometer were used. We discovered a very inclined, ring-like disk at a distance of 65~au from the star. The disk shows a strong brightness asymmetry with respect to its semi-major axis. It shows a smooth outer edge, compatible with ejection of small grains by the stellar radiation pressure. We show furthermore that the planet's projected position is significantly above the disk's PA. Given the determined disk inclination, it is not excluded though that the planet could still orbit within the disk plane if at a large separation (2000--3000 au). We identified several additional point sources in the SPHERE/IRDIS field-of-view, that appear to be background objects. We compare this system with other debris disks sharing similarities, and we briefly discuss the present results in the framework of dynamical evolution





http://arxiv.org/abs/1510.02747

Direct imaging of an asymmetric debris disk in the HD 106906 planetary system

We present the first scattered light detections of the HD 106906 debris disk using Gemini/GPI in the infrared and HST/ACS in the optical. HD 106906 is a 13 Myr old F5V star in the Sco-Cen association, with a previously detected planet-mass candidate HD 106906b projected 650 AU from the host star. Our observations reveal a near edge-on debris disk that has a central cleared region with radius ∼50 AU, and an outer extent >500 AU. The HST data show the outer regions are highly asymmetric, resembling the ''needle'' morphology seen for the HD 15115 debris disk. The planet candidate is oriented ∼21deg away from the position angle of the primary's debris disk, strongly suggesting non-coplanarity with the system. We hypothesize that HD 106906b could be dynamically involved in the perturbation of the primary's disk, and investigate whether or not there is evidence for a circumplanetary dust disk or cloud that is either primordial or captured from the primary. We show that both the existing optical properties and near-infrared colors of HD 106906b are weakly consistent with this possibility, motivating future work to test for the observational signatures of dust surrounding the planet

And also quietly announcing the central star as a binary, making it a circumbinary planet (they give the discovery paper for the second star as being in prep.)

So it would be another circumbinary planet detected through imaging adding to SRS 21 (AB)b or DT Vir (AB)b.

http://www.eso.org/public/unitedkingdom/images/potw1543a/

Planet-hunting SPHERE Images First Circumbinary Planet System with Disc

Any reference on the binary nature of the star exempt this photo?

the discovery paper for the second star is in prep.

Ok thanks. I guess its a small M dwarf

From the Lagrange et al. paper that Led_Zep linked earlier:

Quote :

We recently demonstrated that HD 106906 is a close binary, therefore named HD 106906AB, with a total stellar mass probably greater than 2.5 M_⊙ (Lagrange et al, 2015, subm.)

Mass estimates before the binary nature of the system usually gave ~1.4 solar masses, e.g. the Geneva-Copenhagen survey, which is roughly what would be expected for an F5V (perhaps slightly on the high side). So secondary could well be another F-type or early G-type star. Maybe the similarity of spectral types could have contributed to the binary nature of the star being overlooked?

Need to wait for the paper...

http://spaceref.com/astronomy/exiled-exoplanet-kicked-out-of-stars-local-neighborhood.html

Exiled Exoplanet Kicked Out of Star's Local Neighborhood?

http://arxiv.org/abs/1604.06847

Magellan AO System z ′ , Y S , and L ′ Observations of the Very Wide 650 AU HD 106906 Planetary System

Daemgen et al. "High signal-to-noise spectral characterization of the planetary-mass object HD 106906 b"
https://arxiv.org/abs/1708.05747

Spectral type L1.5±1.0, mass estimate for hot start is 11.9^+1.7_-0.8 Jupiter masses, for cold start it is 14.0^+0.2_-0.5. No evidence for accretion of hydrogen.

Well, the Lagrange et al. paper is still referred to as "submitted" but the basic details of the binary are given in this paper:

Quote :

It turns out to be a 13±2 Myr old SB2 binary consisting of two F5 V-type stars with very similar masses. Table 1 summarizes the key characteristics of the system components.

Table 1 gives the masses as ~1.34 and ~1.37 solar masses, with a projected separation of 0.36–0.58 AU.

Quote :

The binary orbit is also not much constrained yet, but given its short orbital period (< 100 days), it will presumably be better known in the near future.

Wonder if this is what is holding up the publication?

Looks like you can't neglect the binarity of HD 106906 when investigating the dynamics of the disc: the Laplace radius (which separates the region where the binary's quadrupole dominates versus the perturbations from the planet) seems to be right in the middle of the disc.

Farhat et al. "The case of HD 106906 debris disc: A binary's revenge"
https://arxiv.org/abs/2210.07395