J/A+A/567/A128 X-ray sources in WASP-18 field (Pillitteri+, 2014)
No X-rays from WASP-18. Implications for its age, activity, and the influence
of its massive hot Jupiter.
Pillitteri I., Wolk S.J., Sciortino S., Antoci V.
<Astron. Astrophys., 567, A128-128 (2014)>
=2014A&A...567A.128P 2014A&A...567A.128P
ADC_Keywords: X-ray sources
Keywords: stars: activity - stars: coronae - stars: individual: WASP-18
Abstract:
About 20% of the >1000 known exoplanets are Jupiter analogs orbiting
very close to their parent stars. It is still under debate to what
detectable level such hot Jupiters possibly affect the activity of the
host stars through tidal or magnetic star-planet interaction. In this
paper we report on an 87ks Chandra observation of the hot Jupiter
hosting star WASP-18. This system is composed of an F6 type star and a
hot Jupiter of mass 10.4MJup orbiting in less than 20hr around the
parent star. On the basis of an isochrone fitting, WASP-18 is thought
to be 600Myr old and within the range of uncertainty of 0.5-2Gyr. The
star is not detected in X-rays down to a luminosity limit of
4x1026erg/s, which is more than two orders of magnitude lower than
expected for a star of this age and mass. This value proves an unusual
lack of activity for a star with an estimated age around 600Myr. We
argue that the massive planet can play a crucial role in disrupting
the stellar magnetic dynamo created within its thin convective layers.
Other additional 212 X-ray sources are detected in the Chandra image.
We list them and briefly discuss their nature.
Description:
We observed WASP-18 (RA=1h37m24.2s, DE=-45d40m40.3s, J2000) using
Chandra with a continuous ∼87ks long observation with ACIS camera
and CCD numbers 1, 2, 3, 6, 7. WASP-18 falls in the CCD #3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 126 212 List of X-ray sources detected in the ACIS image
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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- 3 I3 --- Seq [1/212] X-ray source sequential number
5- 12 F8.5 deg RAdeg Right ascension (J2000)
14- 22 F9.5 deg DEdeg Declination (J2000)
24- 27 F4.1 arcsec ePos [0.4/13] Positional error
29- 33 F5.2 arcmin Offaxis Off-axis angle θ
35- 39 F5.2 --- Signi [4/29] Significance (in σbkg)
41- 46 F6.2 ct Count [3/918] Counts
48- 52 F5.2 ct e_Count [2.9/83] rms uncertainty on Count
54- 59 F6.3 ct/ks CRate [0.05/10.3] Count rate
61- 65 F5.3 ct/ks e_CRate [0.03/0.93] rms uncertainty on CRate
67- 71 F5.2 ks ExpTime [12/99] Exposure time
73-102 A30 --- OName NED or Simbad name of optical counter part (1)
104-126 A23 --- IName 2MASS name of IR counterpart (1)
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Note (1): From table4 of the paper.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 09-Oct-2014