J/ApJ/880/49 Predictions of giant exoplanet host star's (Hinkel+, 2019)
A recommendation algorithm to predict giant exoplanet host star's using stellar
elemental abundances.
Hinkel N.R., Unterborn C., Kane S.R., Somers G., Galvez R.
<Astrophys. J., 880, 49-49 (2019)>
=2019ApJ...880...49H 2019ApJ...880...49H (SIMBAD/NED BibCode)
ADC_Keywords: Models ; Stars, double and multiple ; Exoplanets
Keywords: methods: statistical - planetary systems -
planets and satellites: detection - stars: abundances
Abstract:
The presence of certain elements within a star, and by extension its
planet, strongly impacts the formation and evolution of the planetary
system. The positive correlation between a host star's iron content
and the presence of an orbiting giant exoplanet has been confirmed;
however, the importance of other elements in predicting giant planet
occurrence is less certain despite their central role in shaping
internal planetary structure. We designed and applied a
machine-learning algorithm to the Hypatia Catalog to analyze the
stellar abundance patterns of known host stars to determine those
elements important in identifying potential giant exoplanet host
stars. We analyzed a variety of different elements ensembles-namely,
volatiles, lithophiles, siderophiles, and Fe. We show that the
relative abundances of oxygen, carbon, and sodium, in addition to
iron, are influential indicators of the presence of a giant planet. We
demonstrate the predictive power of our algorithm by analyzing stars
with known giant planets and found that they had median 75% prediction
score. We present a list of ∼350 stars with no currently
discovered planets that have a ≥90% prediction probability
likelihood of hosting a giant exoplanet. We investigated archival
HARPS data and found significant trends that HIP 62345, HIP 71803, and
HIP 10278 host long-period giant planet companions with estimated
minimum Mpsin(i) values of 3.7, 6.8, and 8.5MJ, respectively.
We anticipate that our findings will revolutionize future target
selection, the role that elements play in giant planet formation, and
the determination of giant planet interior structure models.
Description:
The Hypatia Catalog ( www.hypatiacatalog.com) is a database of
amalgamate stellar abundance data that currently spans 72 unique
elements and species in ∼6000 stars within 150pc of the Sun (Hinkel et
al. 2014, Cat. J/AJ/148/54, 2016ApJS..226....4H 2016ApJS..226....4H, 2017, Cat.
J/ApJ/848/34).
Using our recommendation algorithm, we have compiled a table of the
+4200 target stars with the predicted probabilities that these stars
host a giant planet as determined from the
Volatiles+Lithophiles+Siderophile+Fe ensemble (Table 1). Probabilities
are determined such that the number of times it is positively
predicted to host a giant planet (Pred) is divided by the number of
times each star was sampled (Samp), such that Prob=Pred/Samp. For the
Volatiles+Lithophiles+Siderophile+Fe ensemble, 368 stars, or ∼9% of
the Hypatia stars we predicted on, have prediction probabilities of
hosting a giant planet ≥90%. None of these 368 stars have yet had any
discovered planets, and thus we include the R.A./decl., spectral type,
and V magnitude in anticipation of potential future observations to
detect giant exoplanets orbiting these stars (Table 1).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 170 4259 Predicted Giant Exoplanet Host Stars
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP Hipparcos identifier
8- 17 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
19- 28 F10.6 deg DEdeg Declination in decimal degrees (J2000)
30- 49 A20 --- SpType Spectral type
51- 56 F6.3 mag Vmag V band magnitude
58- 61 I4 --- Sample1 ? Number of times star sampled
in 1st ensemble (1)
63- 66 I4 --- Pred1 ? Predicted to host giant planet
in 1st ensemble (1)
68- 79 F12.9 --- Prob1 ? Overall probability of hosting a giant planet
in 1st ensemble (1)
81- 84 I4 --- Sample2 ? Number of times star sampled
in 2nd ensemble (1)
86- 89 I4 --- Pred2 ? Predicted to host giant planet
in 2nd ensemble (1)
91-102 F12.9 --- Prob2 ? Overall probability of hosting a giant planet
in 2nd ensemble (1)
104-107 I4 --- Sample3 ? Number of times star sampled
in 3rd ensemble (1)
109-112 I4 --- Pred3 ? Predicted to host giant planet
in 3rd ensemble (1)
114-124 F11.9 --- Prob3 ? Overall probability of hosting a giant planet
in 3rd ensemble (1)
126-129 I4 --- Sample4 ? Number of times star sampled
in 4th ensemble (1)
131-134 I4 --- Pred4 ? Predicted to host giant planet
in 4th ensemble (1)
136-147 F12.9 --- Prob4 ? Overall probability of hosting a giant planet
in 4th ensemble (1)
149-152 I4 --- Sample5 ? Number of times star sampled
in 5th ensemble (1)
154-157 I4 --- Pred5 ? Predicted to host giant planet
in 5th ensemble (1)
159-170 F12.9 --- Prob5 ? Overall probability of hosting a giant planet
in 5th ensemble (1)
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Note (1): Definitions:
1st ensemble = Volatiles+Lithophiles+Siderophile+Fe:
C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Mn, Y, Cr, Co, Ni, Fe
2nd ensemble = Volatiles+Lithophiles+Siderophile:
C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Mn, Y, Cr, Co, Ni
3rd ensemble = Volatiles+Lithophiles+Fe:
Na, Mg, Al, Si, Ca, Sc, Ti, V, Mn, Y, Cr, Co, Ni, Fe
4th ensemble = Lithophiles+Siderophile+Fe:
C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Mn, Y, Fe
5th ensemble = Lithophiles+Siderophile:
Na, Mg, Al, Si, Ca, Sc, Ti, V, Mn, Y, Cr, Co, Ni
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Acknowledgements:
Natalie Hinkel, natalie.hinkel(at)gmail.com
(End) Patricia Vannier [CDS] 19-Sep-2019