J/AJ/150/197 Photometry and spectroscopy of HAT-P-57 (Hartman+, 2015)
HAT-P-57b: a short-period giant planet transiting a bright rapidly rotating A8V
star confirmed via Doppler tomography.
Hartman J.D., Bakos G.A., Buchhave L.A., Torres G., Latham D.W., Kovacs G.,
Bhatti W., Csubry Z., de Val-Borro M., Penev K., Huang C.X., Beky B.,
Bieryla A., Quinn S.N., Howard A.W., Marcy G.W., Johnson J.A., Isaacson H.,
Fischer D.A., Noyes R.W., Falco E., Esquerdo G.A., Knox R.P., Hinz P.,
Lazar J., Papp I., Sari P.
<Astron. J., 150, 197 (2015)>
=2015AJ....150..197H 2015AJ....150..197H (SIMBAD/NED BibCode)
ADC_Keywords: Planets ; Stars, double and multiple ; Photometry ;
Radial velocities
Keywords: planetary systems - stars: individual: HAT-P-57 -
techniques: photometric - techniques: spectroscopic
Abstract:
We present the discovery of HAT-P-57b, a P=2.4653 day transiting
planet around a V=10.465±0.029mag, Teff=7500±250K main sequence
A8V star with a projected rotation velocity of vsini=102.1±1.3km/s.
We measure the radius of the planet to be R=1.413±0.054RJ and,
based on RV observations, place a 95% confidence upper limit on its
mass of M<1.85MJ. Based on theoretical stellar evolution models, the
host star has a mass and radius of 1.47±0.12M☉ and
1.500±0.050R☉, respectively. Spectroscopic observations made
with Keck-I/HIRES during a partial transit event show the Doppler
shadow of HAT-P-57b moving across the average spectral line profile of
HAT-P-57, confirming the object as a planetary system. We use these
observations, together with analytic formulae that we derive for the
line profile distortions, to determine the projected angle between the
spin axis of HAT-P-57 and the orbital axis of HAT-P-57b. The data
permit two possible solutions, with -16.7°<λ<3.3° or
27.6°<λ<57.4° at 95% confidence, and with relative
probabilities for the two modes of 26% and 74%, respectively. Adaptive
optics imaging with MMT/Clio2 reveals an object located 2.7" from
HAT-P-57 consisting of two point sources separated in turn from each
other by 0.22". The H- and L'-band magnitudes of the companion stars
are consistent with their being physically associated with HAT-P-57,
in which case they are stars of mass 0.61±0.10M☉ and
0.53±0.08M☉. HAT-P-57 is the most rapidly rotating star, and
only the fourth main sequence A star, known to host a transiting
planet.
Description:
The star HAT-P-57 was observed by the HATNet wide-field photometric
instruments between the nights of UT 2009 May 12 and UT 2009 September
14. A total of 622 observations of a 10.6°*10.6° field
centered at RA=06h24m, decl.=+30° were made with the HAT-5
telescope in Arizona, and 3202 observations of this same field were
made with the HAT-9 telescope in Hawaii. We used a Sloan r filter.
Photometric follow-up observations of HAT-P-57 were carried out with
KeplerCam on the Fred Lawrence Whipple Observatory (FLWO) 1.2m
telescope. We observed ingress events on the nights of 2010 April 3
and 2012 April 24, in i and g-bands respectively, and a full transit
on the night of 2010 June 26 in z-band. Additional photometric
follow-up observations were carried out with the FLWO 1.2m on the
night of 2015 May 12.
All time-series photometric data that we collected for HAT-P-57 are
provided in Table1.
Spectroscopic observations were obtained using the HIgh-Resolution
Echelle Spectrometer (HIRES) on the Keck-I 10m telescope between UT
2010 June 27 and UT 2012 March 10. A total of 24 HIRES observations
were collected during this time period, including 14 observations made
through the I2 cell (e.g., Marcy & Butler, 1992PASP..104..270M 1992PASP..104..270M), and
10 observations without the I2 cell. These latter observations were
obtained on the night of UT 2010 June 27, primarily during a planetary
transit (Section 3.3 discusses the analysis of these observations in
more detail).
Table2 gives the relative radial velocity measurements obtained with
the I2 Doppler pipeline, the radial velocity measurements obtained
from the CCFs, and the Bisector Spans for the HIRES observations.
Objects:
----------------------------------------------------------------------
RA (ICRS) DE Designation(s) (Period)
----------------------------------------------------------------------
18 18 58.43 +10 35 50.1 HAT-P-57 = TYC 1014-973-1 (P=2.4652950)
----------------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 49 4870 Differential photometry of HAT-P-57
table2.dat 55 24 Radial velocities and bisector span measurements
of HAT-P-57 from Keck-I/HIRES
--------------------------------------------------------------------------------
See also:
J/AJ/147/128 : HAT-P-44, HAT-P-45, and HAT-P-46 follow-up (Hartman+, 2014)
J/AJ/147/84 : Photometry and spectroscopy of HAT-P-49 (Bieryla+, 2014)
J/AJ/144/139 : HAT-P-39, HAT-P-40, and HAT-P-41 follow-up (Hartman+, 2012)
J/ApJ/710/1724 : Follow-up photometry for HAT-P-11 (Bakos+, 2010)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 F12.5 d BJD UTC Barycentric Julian date (BJD-2400000) (1)
14- 21 F8.5 mag Dmag [-0.027/0.026] Observed differential magnitude
in Flt (2)
23- 29 F7.5 mag e_Dmag [0.0007/0.008] Uncertainty in Dmag
31- 37 F7.5 mag omag [9.4/9.9]? Raw, observed magnitude (3)
39 A1 --- Flt [griz] Filter used in observation (g, r, i, or z)
41- 49 A9 --- Inst Instrument used (HATNet or KeplerCam) (4)
--------------------------------------------------------------------------------
Note (1): Barycentric Julian Date is computed directly from the UTC time without
correction for leap seconds.
Note (2): The out-of-transit level has been subtracted. These values have
been corrected for trends simultaneously with the transit fit for the
follow-up data. For HATNet trends were filtered before fitting for the
transit.
Note (3): Raw magnitude values after correction using comparison stars, but
without additional trend-filtering. We only report this value for the
KeplerCam observations.
Note (4): Instrument/Telescopes used in the observation:
HATNet = HAT-5 telescope, Arizona; HAT-9 telescope, Hawaii;
KeplerCam = KeplerCam, Fred Lawrence Whipple Observatory (FLWO) 1.2m
telescope.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 d BJD [374.8/997.1] Barycentric Julian Date
(BJD-2455000) (1)
11- 14 I4 m/s RV1 [-626/368]? Radial velocity computed using the
I2 method (2)
16- 17 I2 m/s e_RV1 [45/95]? The 1σ error in RV1 (3)
19- 24 F6.2 km/s RV2 [-10.9/-6.9]? Radial velocity computed using the
CCF method, applied only to the I2-free blue
spectral orders (4)
26- 29 F4.2 km/s e_RV2 [0.8/1.1]? The 1σ error in RV2 (4)
31- 35 F5.2 km/s RV3 [-9.6/-6.7]? Radial velocity computed using the
CCF method, applied to the blue and green
spectral orders (5)
37- 40 F4.2 km/s e_RV3 [0.67/0.81]? The 1σ error in RV3
42- 45 I4 m/s BS [-259/350]? Bisector span
47- 49 I3 m/s e_BS [36/108]? 1σ error in BS
51- 55 F5.3 --- Phase [0/1] Phase (6)
--------------------------------------------------------------------------------
Note (1): Calculated directly from UTC, without correction for leap seconds.
Note (2): The zero-point of these velocities is arbitrary. An overall offset
fitted to these velocities in Section 3 has not been subtracted. Spectra
obtained without the I2-cell in do not have an radial velocity
measurement listed in this column.
Note (3): Internal errors excluding the component of astrophysical jitter
considered in Section 3.
Note (4): Note that the units here are km/s rather than m/s.
Note (5): Observations obtained with the I2-cell in do not have a measurement
listed here.
Note (6): Orbital phase, with phase zero corresponding to mid-transit.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 17-May-2016