J/ApJ/792/L31 HARPS and HARPS-N 55 Cnc radial velocities (Lopez-Morales+, 2014)
Rossiter-McLaughlin observations of 55 Cnc e.
Lopez-Morales M., Triaud A.H.M.J., Rodler F., Dumusque X., Buchhave L.A.,
Harutyunyan A., Hoyer S., Alonso R., Gillon M., Kaib N.A., Latham D.W.,
Lovis C., Pepe F., Queloz D., Raymond S.N., Segransan D., Waldmann I.P.,
Udry S.
<Astrophys. J., 792, L31 (2014)>
=2014ApJ...792L..31L 2014ApJ...792L..31L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Radial velocities
Keywords: planets and satellites: formation -
planets and satellites: individual: 55 Cancri e -
stars: individual: 55 Cnc - techniques: radial velocities -
techniques: spectroscopic
Abstract:
We present Rossiter-McLaughlin observations of the transiting
super-Earth 55 Cnc e collected during six transit events between 2012
January and 2013 November with HARPS and HARPS-N. We detect no radial
velocity signal above 35 cm/s (3σ) and confine the stellar
vsini* to 0.2±0.5 km/s. The star appears to be a very slow
rotator, producing a very low amplitude Rossiter-McLaughlin effect.
Given such a low amplitude, the Rossiter-McLaughlin effect of 55 Cnc e
is undetected in our data, and any spin-orbit angle of the system
remains possible. We also performed Doppler tomography and reach a
similar conclusion. Our results offer a glimpse of the capacity of
future instrumentation to study low amplitude Rossiter-McLaughlin
effects produced by super-Earths.
Description:
Shortly after the detection of 55 Cnc e's transit was announced, we
requested four spectroscopic time series on HARPS (Prog. ID
288.C-5010; PI: Triaud) as Director Discretionary Time. HARPS is
installed on the 3.6 m telescope at the European Southern Observatory
on La Silla, Chile (Mayor et al. 2003Msngr.114...20M 2003Msngr.114...20M). The position of
55 Cnc in the sky-RA(J2000)=08:52:35.81, DE(J2000)=+28:10:50.95-is low
as seen from La Silla. The target remains at a zenith distance of z<2
for only ∼2.5 hr per night, with a transit duration of about 1.5 hr
having to fit within this tight window. This constraint on the
airmass, essential to obtain precise radial velocities (RVs), is set
by the instrumental atmospheric dispersion corrector. We used the
ephemeris by Gillon et al. (2012, J/A+A/539/A28), then at an advanced
stage of preparation, to schedule our observations. In total, we
gathered 179 spectra on the nights starting on 2012 January 27, 2012
February 13, 2012 February 27, and 2012 March 15 UT.
Objects:
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RA (ICRS) DE Designation(s)
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08 52 35.81 +28 19 51.0 55 Cnc e = NAME Janssen
08 52 35.81 +28 19 51.0 55 Cnc = GC 12244
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 81 293 Radial velocities of all spectra of 55 Cnc
observed with HARPS and HARPS-N
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See also:
J/A+A/533/A114 : Transit of super-Earth 55 Cnc e (Demory+, 2011)
J/A+A/539/A28 : New transit photometry for super-Earth 55 Cnc e
(Gillon+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d BJD Barycentric Julian Date (BJD-2400000)
14- 21 F8.5 km/s RV Radial Velocity
23- 29 F7.5 km/s e_RV Error in RV
31- 37 F7.5 km/s FWHM Full Width at Half Maximum
39- 46 F8.5 km/s BisSpan Bisector slope span
48- 53 F6.2 --- S/N Signal-to-Noise ratio at 6240Å
55- 58 F4.2 --- Airmass Airmass
60- 65 F6.2 arcsec Seeing ? Seeing from La Silla seeing monitor
67- 71 F5.1 s ExpTime Exposure time
73- 81 F9.6 km/s RVcorr Corrected Radial Velocity (1)
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Note (1): With the five planet Doppler displacement removed.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 05-Apr-2017