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J/AJ/153/138           Radial velocity curve of 51 Peg           (Birkby+, 2017)

Discovery of water at high spectral resolution in the atmosphere of 51 Peg b. Birkby J.L., de Kok R.J., Brogi M., Schwarz H., Snellen I.A.G. <Astron. J., 153, 138-138 (2017)> =2017AJ....153..138B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Radial velocities Keywords: planetary systems - planets and satellites: composition - planets and satellites: gaseous planets - planets and satellites: individual: 51 Peg b Abstract: We report the detection of water absorption features in the day side spectrum of the first-known hot Jupiter, 51 Peg b, confirming the star-planet system to be a double-lined spectroscopic binary. We use high-resolution (R~100000), 3.2µm spectra taken with CRIRES/VLT to trace the radial-velocity shift of the water features in the planet's day side atmosphere during 4 hr of its 4.23 day orbit after superior conjunction. We detect the signature of molecular absorption by water at a significance of 5.6σ at a systemic velocity of Vsys=-33±2km/s, coincident with the 51 Peg host star, with a corresponding orbital velocity KP=133-3.5+4.3km/s. This translates directly to a planet mass of Mp=0.476-0.031+0.032MJ, placing it at the transition boundary between Jovian and Neptunian worlds. We determine upper and lower limits on the orbital inclination of the system of 70°<i<82.2°. We also provide an updated orbital solution for 51 Peg b, using an extensive set of 639 stellar radial velocities measured between 1994 and 2013, finding no significant evidence of an eccentric orbit. We find no evidence of significant absorption or emission from other major carbon-bearing molecules of the planet, including methane and carbon dioxide. The atmosphere is non-inverted in the temperature-pressure region probed by these observations. The deepest absorption lines reach an observed relative contrast of 0.9*10-3 with respect to the host star continuum flux at an angular separation of 3 milliarcseconds. This work is consistent with a previous tentative report of K-band molecular absorption for 51 Peg b by Brogi et al. Description: We observed the bright star 51 Peg (G2.5V, V=5.46mag, K=3.91mag) for 3.7hr during the night beginning 2010 October 21, using the CRyogenic InfraRed Echelle Spectrograph (CRIRES) mounted at Nasmyth A at the VLT (8.2 m UT1/Antu), Cerro Paranal, Chile. The observations were collected as part of the ESO large program 186.C-0289. The instrument setup consisted of a 0.2 arcsec slit centred on 3236nm (order 17), in combination with the Multi-Application Curvature Adaptive Optic system (MACAO). The CRIRES infrared detector is comprised of four Aladdin III InSb-arrays, each with 1024*512 pixels, and separated by a gap of 280 pixels. The resulting wavelength coverage of the observations was 3.1806<λ(µm)<3.2659 with a resolution of R~100000 per resolution element. We observed 51 Peg continuously while its hot Jupiter companion passed through orbital phases 0.55≲Φ≲0.58, corresponding to an expected change in the planet's radial velocity of ΔRVP=-23km/s (15 pixels on the CRIRES detectors). In total, we obtained 42 spectra, with the first 20 spectra each consisting of two sets of 5*20s exposures, and the remainder each consisting of two sets of 5*30s exposures. The increase in the exposure time was aimed at maintaining a constant signal-to-noise ratio (S/N) in the continuum of the observed stellar spectra after a sudden and significant deterioration of the seeing (increasing from 0.75 to 1.4 arcsec between one set of frames, see Section 2.3). To enable accurate sky-background subtraction, the telescope was nodded along the slit by 10 arcsec between each set of exposures in a classic ABBA sequence, with each of the final 42 extracted spectra consisting of an AB or BA pair. A standard set of CRIRES calibration frames was taken the following morning. To ensure we had its most up-to-date orbital solution, we compiled an extensive repository of literature and archival radial velocity measurements of the star 51 Peg from multiple observatories. These data are given in Table 1 and span observing dates from 1994 September 15 to 2014 July 9, resulting in 639 radial velocity measurements over 20 years. The table includes the discovery measurements from the ELODIE spectrograph at Observatoire Haute Provence and subsequent additional monitoring. We took these radial velocity measurements from the Naef et al. 2004 (Cat. J/A+A/414/351) compilation. We also included the legacy data set from Lick Observatory observed with the Hamilton spectrograph, taking measurements from the self-consistent reprocessing of all the Lick spectra presented by Fischer et al. 2014 (Cat. J/ApJS/210/5). Finally, we included more recent additional monitoring from the High Resolution Echelle Spectrometer (HIRES) at the Keck Observatory, and extracted RVs from observations with the High Accuracy Radial velocity Planet Searcher (HARPS) at the ESO-3.6m telescope in 2013 (ESO program ID 091.C-0271, PI: Santos). The reduced HARPS spectra were obtained from the ESO Science Archive (http://archive.eso.org/wdb/wdb/adp/phase3_spectral/query). Objects: ------------------------------------------------------------- RA (ICRS) DE Designation(s) (Period) ------------------------------------------------------------- 22 57 27.98 +20 46 07.8 * 51 Peg = HR 8729 (P=4.2307869) ------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 51 639 Stellar radial velocity measurements of 51 Peg from multiple observatories
See also: J/A+A/576/A134 : Radial velocities of 51 Peg (Martins+, 2015) J/ApJS/210/5 : The twenty-five year Lick planet search (Fischer+, 2014) J/ApJ/646/505 : Catalog of nearby exoplanets (Butler+, 2006) J/A+A/414/351 : ELODIE survey for northern extrasolar planets (Naef+, 2004) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 16 F16.8 d BJD Barycentric Julian Date (BJDTDB) (1) 18- 32 F15.8 m/s RV [-33332/132.82] Radial velocity (2) 34- 44 F11.8 m/s e_RV [0.174537/22.17] Uncertainty in RV (σRV) 46- 51 A6 --- Set Dataset identifier (either ELODIE, HARPS, HIRES, Lick6, Lick8, or Lick13) (3)
Note (1): Barycentric Dynamical Time. Note (2): The Lick8 radial velocities reported include a +13.1m/s velocity offset correction to the radial velocities extracted from Vizier, to account for the instrumental systematic reported in Fischer et al. 2014 (Cat. J/ApJS/210/5). The following additional offsets, determined from a circular orbit fit to each dataset using EXOFAST, can be applied to place all of the radial velocity measurements onto the same zero-point: γLick13=-21.70m/s, γLick8 =-4.52m/s, γLick6=-14.64m/s, γELODIE=+33251.59m/s, γHIRES =+2.24m/s, γHARPS=+33152.54m/s. Note (3): The discovery measurements datasets are defined as follows: ELODIE = The ELODIE spectro-graph at Observatoire Haute Provence and subsequent additional monitoring. We took these radial velocities measurements from the Naef et al. 2004 (Cat. J/A+A/414/351) compilation; Lick6 = Hamilton spectrograph at the Lick Observatory. The numbers in the Lick dataset names denote the dewar associated with each upgrade to the Hamilton spectrograph, which introduced different velocity offsets; Lick8 = Hamilton spectrograph at the Lick Observatory. The numbers in the Lick dataset names denote the dewar associated with each upgrade to the Hamilton spectrograph, which introduced different velocity offsets; Lick13 = Hamilton spectrograph at the Lick Observatory. The numbers in the Lick dataset names denote the dewar associated with each upgrade to the Hamilton spectrograph, which introduced different velocity offsets; HIRES = High Resolution Echelle Spectrometer (HIRES) at the Keck Observatory; HARPS = High Accuracy Radial velocity Planet Searcher (HARPS) at the ESO-3.6m telescope in 2013 (ESO program ID 091.C-0271, PI: Santos).
History: From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 27-Jul-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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