ROXs 42Bb

{{Short description|Circumbinary planetary-mass object orbiting ROXs 42B}}

{{Use Canadian English|date=March 2023}}

{{Use mdy dates|date=March 2023}}

{{Infobox planet

| name = ROXs 42Bb

| image = File:ROXs 42B MUSE IR.jpg

| image_scale =

| caption = ROXs 42B and its companion (small red object on the right) with VLT MUSE

| discoverer = Currie et al. & Kraus et al.

| discovery_site = Keck Telescope, Very Large Telescope, Subaru Telescope

| discovered = December, 2013

| discovery_method = Direct imaging

| period = 1968.3 years{{cite web | url=https://exoplanets.nasa.gov/exoplanet-catalog/7139/roxs-42-b-b/ | title=Exoplanet-catalog }}

| apsis = astron

| star = ROXs 42B

| mean_radius = {{val|2.10|0.35}}{{Cite journal |last1=Xuan |first1=Jerry W. |last2=Hsu |first2=Chih-Chun |last3=Finnerty |first3=Luke |last4=Wang |first4=Jason |last5=Ruffio |first5=Jean-Baptiste |last6=Zhang |first6=Yapeng |last7=Knutson |first7=Heather A. |last8=Mawet |first8=Dimitri |last9=Mamajek |first9=Eric E. |last10=Inglis |first10=Julie |last11=Wallack |first11=Nicole L. |last12=Bryan |first12=Marta L. |last13=Blake |first13=Geoffrey A. |last14=Mollière |first14=Paul |last15=Hejazi |first15=Neda |date=2024-07-01 |title=Are These Planets or Brown Dwarfs? Broadly Solar Compositions from High-resolution Atmospheric Retrievals of ∼10–30 M Jup Companions |journal=The Astrophysical Journal |volume=970 |issue=1 |pages=71 |arxiv=2405.13128 |bibcode=2024ApJ...970...71X |doi=10.3847/1538-4357/ad4796 |doi-access=free |issn=0004-637X}}

{{Jupiter radius|link=y}}

| mass = {{val|13|5}} {{Jupiter mass|link=y}}

| surface_grav = 3.2 - 12.8 g

| single_temperature = 2240{{+-|150}} K

}}

ROXs 42Bb is a directly imaged planetary-mass companion{{Cite journal |title=Direct Imaging and Spectroscopy of a Candidate Companion Below/Near the Deuterium-Burning Limit In The Young Binary Star System, ROXs 42B |first1=Thayne |last1=Currie | first2 = Sebastian | last2 = Daemgen | first3 = John | last3 = Debes | first4 = David | last4 = Lafreniere | first5 = Yoichi | last5 = Itoh | first6 = Ray | last6 = Jayawardhana | first7 = Thorsten | last7 = Ratzka | first8 = Serge | last8 = Correia |journal = The Astrophysical Journal Letters|bibcode = 2014ApJ...780L..30C|doi = 10.1088/2041-8205/780/2/L30|year=2014|volume=780|issue=2 |pages=30|arxiv= 1310.4825 |s2cid=118464822 }} to the binary M star ROXs 42B,{{Cite journal| first1=Michael | last1=Simon | first2=A. M. | last2 = Ghez | first3=Ch. | last3 = Leinert | first4=L. | last4 = Cassar | first5=W. P. | last5 = Chen | first6=R. R. | last6 = Howell | first7=R. F. | last7 = Jameson | first8=K. | last8 = Matthews | first9=G. | last9 = Neugebauer | first10=A. | last10 = Richichi |journal = The Astrophysical Journal | title=A lunar occultation and direct imaging survey of multiplicity in the Ophiuchus and Taurus star-forming regions|bibcode = 1995ApJ...443..625S|doi = 10.1086/175554|year=1995|volume=443|pages=625 | s2cid=122944079 | url=https://authors.library.caltech.edu/84585/1/1995ApJ___443__625S.pdf }} a likely member of the Rho Ophiuchi cloud complex. The companion was independently discovered in December, 2013, by astronomers from University of Texas at Austin & University of Toronto.{{Cite journal |last=Kraus |first=Adam L. |last2=Ireland |first2=Michael J. |last3=Cieza |first3=Lucas A. |last4=Hinkley |first4=Sasha |last5=Dupuy |first5=Trent J. |last6=Bowler |first6=Brendan P. |last7=Liu |first7=Michael C. |date=2013-12-31 |title=THREE WIDE PLANETARY-MASS COMPANIONS TO FW TAU, ROXs 12, AND ROXs 42B |url=https://iopscience.iop.org/article/10.1088/0004-637X/781/1/20 |journal=The Astrophysical Journal |volume=781 |issue=1 |pages=20 |arxiv=1311.7664 |bibcode=2014ApJ...781...20K |doi=10.1088/0004-637X/781/1/20 |issn=0004-637X}}

The object has a best estimated mass around 9 to 10 Jupiter masses, depending on the age of the star, similar to the masses of directly imaged planets around HR 8799 and beta Pictoris. However, it is unclear whether ROXs 42Bb formed like these planets via core accretion, by disk (gravitational) instability, or more like a binary star. Preliminary fits of the spectra and broadband photometry to atmospheric models imply a radius of {{jupiter radius|2.43 ± 0.18}} for an effective temperature of about 2,000 K or a radius of {{jupiter radius|2.55 ± 0.20}} for about 1950 K. Like Beta Pictoris b, ROXs 42Bb's atmosphere is likely very cloudy and dusty.{{Cite journal |title=A First-Look Atmospheric Modeling Study of the Young Directly-Imaged Planet-Mass Companion, ROXs 42Bb |first1=Thayne |last1=Currie | first2 = Adam | last2 = Burrows | first3 = Sebastian | last3 = Daemgen |year=2014 |arxiv= 1404.0131 | doi=10.1088/0004-637X/787/2/104 | volume=787 |issue=2 | journal=The Astrophysical Journal | page=104|bibcode = 2014ApJ...787..104C |s2cid=118376549 }}

The object is located in the constellation Ophiuchus, near the border with Scorpius.