J/AJ/167/64 HD 136164 Ab IR spectrum with VLTI/GRAVITY (Balmer+, 2024)
VLTI/GRAVITY Provides Evidence the Young, Substellar Companion HD 136164 Ab
Formed Like a "Failed Star".
Balmer W.O., Pueyo L., Lacour S., Wang J.J., Stolker T., Kammerer J.,
Pourre N., Nowak M., Rickman E., Blunt S., Sivaramakrishnan A., Sing D.,
Wagner K., Marleau G.-D., Lagrange A.-M., Abuter R., Amorim A.,
Asensio-Torres R., Berger J.-P., Beust H., Boccaletti A., Bohn A.,
Bonnefoy M., Bonnet H., Bordoni M.S., Bourdarot G., Brandner W.,
Cantalloube F., Caselli P., Charnay B., Chauvin G., Chavez A., Choquet E.,
Christiaens V., Clenet Y., du Foresto V.C., Cridland A., Davies R.,
Dembet R., Drescher A., Duvert G., Eckart A., Eisenhauer F.,
Schreiber N.M.F., Garcia P., Garcia Lopez R., Gendron E., Genzel R.,
Gillessen S., Girard J.H., Grant S., Haubois X., Heissel G., Henning T.,
Hinkley S., Hippler S., Houlle M., Hubert Z., Jocou L., Keppler M.,
Kervella P., Kreidberg L., Kurtovic N.T., Lapeyrere V., Le Bouquin J.-B.,
Lena P., Lutz D., Maire A.-L., Mang F., Merand A., Molliere P.,
Mordasini C., Mouillet D., Nasedkin E., Ott T., Otten G.P.P.L.,
Paladini C., Paumard T., Perraut K., Perrin G., Pfuhl O., Ribeiro D.C.,
Rodet L., Rustamkulov Z., Shangguan J., Shimizu T., Straubmeier C.,
Sturm E., Tacconi L.J., Vigan A., Vincent F., Ward-Duong K., Widmann F.,
Winterhalder T., Woillez J., Yazici S., the GRAVITY Collaboration
<Astron. J., 167, 64 (2024)>
=2024AJ....167...64B 2024AJ....167...64B
ADC_Keywords: Stars, brown dwarf; Exoplanets; Spectra, infrared
Keywords: Brown dwarfs ; Substellar companion stars ; Orbit determination
; Orbits
Abstract:
Young, low-mass brown dwarfs orbiting early-type stars, with low mass
ratios (q≲0.01), appear to be intrinsically rare and present a
formation dilemma: could a handful of these objects be the
highest-mass outcomes of "planetary" formation channels (bottom up
within a protoplanetary disk), or are they more representative of the
lowest-mass "failed binaries" (formed via disk fragmentation or core
fragmentation)? Additionally, their orbits can yield model-independent
dynamical masses, and when paired with wide wavelength coverage and
accurate system age estimates, can constrain evolutionary models in a
regime where the models have a wide dispersion depending on the
initial conditions. We present new interferometric observations of the
16Myr substellar companion HD136164Ab (HIP75056Ab) made with the Very
Large Telescope Interferometer (VLTI)/GRAVITY and an updated orbit fit
including proper motion measurements from the Hipparcos-Gaia Catalog
of Accelerations. We estimate a dynamical mass of 35±10MJ
(q∼0.02), making HD136164Ab the youngest substellar companion with a
dynamical mass estimate. The new mass and newly constrained orbital
eccentricity (e=0.44±0.03) and separation (22.5±1au) could
indicate that the companion formed via the low-mass tail of the
initial mass function. Our atmospheric fit to a SPHINX M-dwarf model
grid suggests a subsolar C/O ratio of 0.45 and 3 x solar metallicity,
which could indicate formation in a circumstellar disk via disk
fragmentation. Either way, the revised mass estimate likely excludes
bottom-up formation via core accretion in a circumstellar disk.
HD136164Ab joins a select group of young substellar objects with
dynamical mass estimates; epoch astrometry from future Gaia data
releases will constrain the dynamical mass of this crucial object
further.
Description:
HD136164Ab was first detected using SPHERE at ESO's VLT. We observed
HD136164A and Ab four times between 2022 February and 2023 May using
the GRAVITY instrument at the European Southern Observatory (ESO)'s
VLTI. We used the four 8.2m unit telescopes (UTs).
Objects:
-------------------------------------------------
RA (2000) DE Designation(s)
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15 20 13.39 -34 55 31.5 HD 136164 = ** KOU 36A
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig4.dat 23 240 *The spectrum of HD 136164 Ab
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Note on fig4.dat : The Spectro-Polarimetic High contrast imager for
Exoplanets REsearch (SPHERE) spectrum covers 1-1.6micron and includes
flux uncertainties. The GRAVITY spectrum spans the 2-2.4micron region
and includes flux uncertainties computed from the square root of the
diagonal of the full covariance matrix, which can be found in the FITS
file.
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See also:
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+AS/141/371 : Low-mass stars evolution tracks & isochrones (Girardi+, 2000)
J/A+A/464/581 : Sco OB2 intermediate-mass stars (Kouwenhoven+, 2007)
J/AJ/144/64 : Solar neighborhood XXVIII. Substellar comp (Dieterich+, 2012)
J/A+A/547/A105 : D-burning in core accretion objects (Molliere+, 2012)
J/A+A/564/A125 : AGN Torus model comparison of AGN in CDFS (Buchner+, 2014)
J/MNRAS/461/794 : Scorpius-Centaurus K-Type Stars (Pecaut+, 2016)
J/A+A/605/L9 : NIR spectrum of exoplanet HIP 65426b (Chauvin+, 2017)
J/ApJS/231/15 : Astrometric monito of ultracool dwarf binaries (Dupuy+, 2017)
J/AJ/155/149 : Properties of comoving stars obs by Gaia (Bochanski+, 2018)
J/ApJ/856/23 : BANYAN. XI. The BANYAN Σ algorithm (Gagne+, 2018)
J/AJ/155/226 : Gemini Planet Imager spectra HR8799 c/d/e (Greenbaum+, 2018)
J/A+A/623/A72 : Bin of Hipparcos stars from Gaia pm anomaly (Kervella+, 2019)
J/AJ/158/13 : The first 300 stars observed by the GPIES (Nielsen+, 2019)
J/AJ/159/63 : AO obs of exoplanets & brown dwarf companions (Bowler+, 2020)
J/A+A/633/A110 : K band spectrum of beta Pictoris b (GRAVITY+, 2020)
J/AJ/160/215 : Sun neighborhood.XLVI. New M dwarf binaries (Vrijmoet+, 2020)
J/ApJS/254/42 : Hipparcos-Gaia (EDR3) Catalog of Accelerations (Brandt, 2021)
J/AJ/161/172 : Sun Neighborhood. XLVII. Mdwarfs with STIS (Dieterich+, 2021)
J/A+A/657/A53 : Wideorbit companions to K-type stars in Sco-Cen (Bohn+, 2022)
J/A+A/657/A7 : Stellar & substellar companions Gaia EDR3 (Kervella+, 2022)
J/AJ/163/178 : Solar Neighborhood XLIV. M dwarfs with SOAR (Vrijmoet+, 2022)
J/AJ/163/80 : The Scorpion Planet Survey; A-stars IR spectr (Wagner+, 2022)
Byte-by-byte Description of file: fig4.dat
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Bytes Format Units Label Explanations
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1- 5 F5.3 um Wave [1.02/2.43] Wavelength
7- 14 E8.2 W/m2/um Flux [5e-16/5e-15] Flux density
16- 23 E8.2 W/m2/um e_Flux [1e-17/4e-16]? Uncertainty in Flux
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 26-Apr-2024