J/ApJ/799/163 Chandra observations of solar analogs (Miller+, 2015)
A comprehensive statistical assessment of star-planet interaction.
Miller B.P., Gallo E., Wright J.T., Pearson E.G.
<Astrophys. J., 799, 163 (2015)>
=2015ApJ...799..163M 2015ApJ...799..163M
ADC_Keywords: Stars, double and multiple ; X-ray sources ; Planets
Keywords: planetary systems; stars: activity; stars: magnetic field
Abstract:
We investigate whether magnetic interaction between close-in giant
planets and their host stars produce observable statistical
enhancements in stellar coronal or chromospheric activity. New Chandra
observations of 12 nearby (d<60pc) planet-hosting solar analogs are
combined with archival Chandra, XMM-Newton, and ROSAT coverage of 11
similar stars to construct a sample inoculated against inherent
stellar class and planet-detection biases. Survival analysis and
Bayesian regression methods (incorporating both measurements errors
and X-ray upper limits; 13/23 stars have secure detections) are used
to test whether "hot Jupiter" hosts are systematically more X-ray
luminous than comparable stars with more distant or smaller planets.
No significant correlations are present between common proxies for
interaction strength (MP/a2 or 1/a) versus coronal activity (LX
or LX/Lbol). In contrast, a sample of 198 FGK main-sequence stars
does show a significant (∼99% confidence) increase in X-ray luminosity
with MP/a2. While selection biases are incontrovertibly present
within the main-sequence sample, we demonstrate that the effect is
primarily driven by a handful of extreme hot-Jupiter systems with
MP/a2>450MJupAU-2, which here are all X-ray luminous but to a
degree commensurate with their Ca II H and K activity, in contrast to
presented magnetic star-planet interaction scenarios that predict
enhancements relatively larger in LX. We discuss these results in
the context of cumulative tidal spin-up of stars hosting close-in gas
giants (potentially followed by planetary infall and destruction). We
also test our main-sequence sample for correlations between planetary
properties and UV luminosity or Ca II H and K emission, and find no
significant dependence.
Description:
XMM-Newton observations targeting planet-hosting stars within d<30pc
(Kashyap et al. 2008ApJ...687.1339K 2008ApJ...687.1339K; Poppenhager et al.
2010A&A...515A..98P 2010A&A...515A..98P) include an five additional solar analogs (47 UMa,
HD190360, HD217107, 16 Cyg B, and HD70642; 51Peg and HD4308 also have
XMM-Newton coverage), for which we take LX measurements from
Poppenhager et al. (2010A&A...515A..98P 2010A&A...515A..98P). For completeness we also
include complementary ROSAT coverage of five solar analogs at d<30pc
(HD39091, HD82943, HD147513, HD150706, HD210277), calculating LX from
RASS bright or faint source catalog net count rates.
Chandra archival coverage of solar analogs includes observations of
51Peg (ObsID 10825; PI: Schmitt), HD4308 (ObsID 12339), and ρ CrB
(ObsID 12396). We reprocessed these data.
To this archival data we add our 12 new Chandra/ACIS-S observations
(PI: Miller, ObsIDs 13658-13669) to construct a sample of 23 solar
analogs with sensitive X-ray coverage.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 103 198 Sample properties
table2.dat 104 15 Chandra (archival and new) observations of
solar analogs
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
J/A+A/567/A128 : X-ray sources in WASP-18 field (Pillitteri+, 2014)
J/A+A/552/A119 : Planet-star and moon-planet interaction (Saur+, 2013)
J/ApJ/766/9 : GALEX observations of exoplanet host stars (Shkolnik, 2013)
J/A+A/540/A82 : CaIIHK emission in stars with close planets (Krejcova+, 2012)
J/PASP/123/412 : Exoplanet Orbit Database (Wright+, 2011)
J/MNRAS/411/L46 : Exoplanet magnetic fields (Vidotto+, 2011)
J/ApJ/725/875 : Chromospheric activity for CPS stars (Isaacson+, 2010)
J/ApJS/182/97 : Radial velocities of multi-planet systems (Wittenmyer+, 2009)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/A+A/475/359 : Predicting radio fluxes of exoplanets (Griessmeier+, 2007)
J/ApJ/646/523 : Exoplanet systems with stellar companions (Raghavan+, 2006)
J/ApJ/622/1102 : The planet-metallicity correlation. (Fischer+, 2005)
J/ApJS/152/261 : Chromospheric Ca II emission in nearby stars (Wright+, 2004)
J/A+A/333/231 : O-M stars model atmospheres (Bessell+ 1998)
http://exoplanets.org/ : Exoplanet Orbit Database home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Name of host star (1)
13 A1 --- m_Name Component ID of the primary planet (1)
15- 18 I4 K Teff [4640/6387] Effective stellar temperature
20- 24 F5.2 [10-7W] Lbol [32.7/34.4] Log bolometric luminosity; erg/s
26- 31 F6.2 --- R'HK [-5.2/-4.42]?=-99 R'HK activity index
33- 38 F6.2 m/s RMS [0.7/62]?=-99 RMS velocity
40- 44 F5.2 Mjup Msini [0.01/19] Minimum planet mass in Jupiter units
46- 50 F5.3 AU a [0.03/6.8] Semi-major axis of planetary orbit
52- 58 F7.2 d Period [2.2/5894] Planetary orbital period
60- 66 F7.2 m/s K [0.7/1813] Radial velocity semi-amplitude
68- 74 F7.2 Mjup/AU2 Mp/a2 The Mp/a2 ratio
76- 80 F5.2 AU-1 1/a [0.1/33] Inverse separation
82- 86 F5.2 [10-7W] Lx [26/29.6] Log X-ray luminosity; erg/s
88- 91 F4.2 [10-7W] e_Lx [0/0.4] Uncertainty on Lx
93- 97 F5.2 [-] Lx/Lb Log X-ray to bolometric luminosity ratio
99 I1 --- X [0/1] X-ray detection; 1=det and 0=limit
101 A1 --- Obs Observatory for Lx (2)
103 I1 --- S [0/2] in solar analog sample (1=yes) (3)
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Note (1): Most non-X-ray properties were taken from the Exoplanet Orbit
Database and the most current values with uncertainties are
at exoplanets.org.
Note (2): Observatory as follows:
L = RASS limit;
B = Bright RASS source;
F = Faint RASS source;
P = ROSAT pointed PSPC detection;
H = ROSAT HRI detection;
X = XMM-Newton detection or limit;
C = Chandra detection or limit;
O = Other as explained in paper.
Note (3): Include in the solar analog with sensitive X-ray coverage sample:
0 = no
1 = yes (23 stars)
2 = HD147513 and HD150706, solar analogs with ROSAT coverage are quite
active (likely because they are young), with logR'HK>-4.5, and they
are set aside for this analysis (see section 2.2).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name
12- 16 I5 --- ObsID [10825/13669] Chandra observation identifier
18 A1 --- f_ObsID [a] observations from Chandra Archive (1)
20- 29 F10.2 d HJD Heliocentric Julian Date at the beginning
of the observation
31- 35 F5.3 --- phi [0/1] Radial-velocity orbital phase φ
relative to our line of sight
37- 41 F5.2 ks Exp [4.9/14.9] Effective exposure time
43 A1 --- l_Cts Limit flag on Cts
45- 49 F5.2 ct Cts [2.9/42.8] Net counts within a 2" aperture (2)
51 A1 --- f_Cts [b] (1)
53 A1 --- l_Rate Limit flag on Rate
55- 58 F4.2 ct/ks Rate [0.2/3.6] Net counts per ks
60 A1 --- l_Flux Limit flag on Flux
62- 66 F5.2 aW/m2 Flux [0.8/14.2] Unabsorbed 0.2-2keV flux for a
mekal model with logT=7
68- 72 F5.2 pc Dist [15/58] Distance calculated
from Hipparcos parallax
74 A1 --- l_Lx Limit flag on Lx
76- 80 F5.2 [10-7W] Lx [26/27.7] Log of 0.2-2keV X-ray luminosity
in erg/s
82- 85 F4.2 [10-7W] e_Lx [0.1/0.4]? Lx uncertainty
87- 90 F4.2 mag Vmag [5.3/8.5] Apparent V-band magnitude
92- 96 F5.2 [10-7W] Lbol [33.5/33.9] Bolometric luminosity
98 A1 --- l_Lx/Lb Limit flag on Lx/Lb
100-104 F5.2 [-] Lx/Lb [-8/-5.9] Log X-ray to bolometric luminosity
ratio
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Note (1): Flag as follows:
a = From archival Chandra data; see Section 2.2.
All other Chandra observations are from our Cycle 13 program.
b = HD134987 is formally a detection at >90% confidence with our
conservative methodology but is found by wavdetect; see Section 2.2.
Note (2): The net counts within a 2" aperture centered on the object coordinates
at the time of the observation, or else the 95% confidence upper limit.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 17-Jun-2015