You can manage bookmarks using lists, please log in to your user account for this.
Media type:
E-Article
Title:
Moderate-resolution K-band Spectroscopy of the Substellar Companion VHS 1256 b
Contributor:
Hoch, Kielan K. W.;
Konopacky, Quinn M.;
Barman, Travis S.;
Theissen, Christopher A.;
Brock, Laci;
Perrin, Marshall D.;
Ruffio, Jean-Baptiste;
Macintosh, Bruce;
Marois, Christian
imprint:
American Astronomical Society, 2022
Published in:The Astronomical Journal
Language:
Not determined
DOI:
10.3847/1538-3881/ac84d4
ISSN:
0004-6256;
1538-3881
Origination:
Footnote:
Description:
<jats:title>Abstract</jats:title>
<jats:p>We present moderate-resolution (<jats:italic>R</jats:italic> ∼ 4000) <jats:italic>K</jats:italic>-band spectra of the planetary-mass companion VHS 1256 b. The data were taken with the OSIRIS integral field spectrograph at the W.M. Keck Observatory. The spectra reveal resolved molecular lines from H<jats:sub>2</jats:sub>O and CO. The spectra are compared to custom PHOENIX atmosphere model grids appropriate for young, substellar objects. We fit the data using a Markov chain Monte Carlo forward-modeling method. Using a combination of our moderate-resolution spectrum and low-resolution broadband data from the literature, we derive an effective temperature of 1240 K, with a range of 1200–1300 K, a surface gravity of log <jats:italic>g</jats:italic> = 3.25, with a range of 3.25–3.75, and a cloud parameter of <jats:inline-formula>
<jats:tex-math>
<?CDATA $\mathrm{log}{P}_{\mathrm{cloud}}=6$?>
</jats:tex-math>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:mi>log</mml:mi>
<mml:msub>
<mml:mrow>
<mml:mi>P</mml:mi>
</mml:mrow>
<mml:mrow>
<mml:mi>cloud</mml:mi>
</mml:mrow>
</mml:msub>
<mml:mo>=</mml:mo>
<mml:mn>6</mml:mn>
</mml:math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ajac84d4ieqn1.gif" xlink:type="simple" />
</jats:inline-formula>, with a range of 6.0–6.6. These values are consistent with previous studies, regardless of the new, larger system distance from GAIA EDR3 (21.15 <jats:inline-formula>
<jats:tex-math>
<?CDATA $\pm $?>
</jats:tex-math>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:mo>±</mml:mo>
</mml:math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ajac84d4ieqn2.gif" xlink:type="simple" />
</jats:inline-formula> 0.22 pc). We derive a C/O ratio of <jats:inline-formula>
<jats:tex-math>
<?CDATA ${0.590}_{-0.354}^{+0.280}$?>
</jats:tex-math>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:msubsup>
<mml:mrow>
<mml:mn>0.590</mml:mn>
</mml:mrow>
<mml:mrow>
<mml:mo>−</mml:mo>
<mml:mn>0.354</mml:mn>
</mml:mrow>
<mml:mrow>
<mml:mo>+</mml:mo>
<mml:mn>0.280</mml:mn>
</mml:mrow>
</mml:msubsup>
</mml:math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ajac84d4ieqn3.gif" xlink:type="simple" />
</jats:inline-formula> for VHS 1256b. Both our OSIRIS data and spectra from the literature are best modeled when using a larger 3 <jats:italic>μ</jats:italic>m grain size for the clouds than used for hotter objects, consistent with other sources in the L/T transition region. VHS 1256 b offers an opportunity to look for systematics in the modeling process that may lead to the incorrect derivation of properties like C/O ratio in the high contrast regime.</jats:p>