Determining Empirical Stellar Masses and Radii from Transits and Gaia Parallaxes as Illustrated by Spitzer Observations of KELT-11b

Thomas G. Beatty, Daniel J. Stevens, Karen A. Collins, Knicole D. Colón, David J. James, Laura Kreidberg, Joshua Pepper, Joseph E. Rodriguez, Robert J. Siverd, Keivan G. Stassun, John F. Kielkopf

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Using the Spitzer Space Telescope, we observed a transit at 3.6 μm of KELT-11b. We also observed three partial planetary transits from the ground. We simultaneously fit these observations, ground-based photometry from Pepper et al., radial velocity data from Pepper et al., and a spectral energy distribution (SED) model using catalog magnitudes and the Hipparcos parallax to the system. The only significant difference between our results and those of Pepper et al. is that we find the orbital period to be shorter by 37 s, 4.73610 ±0.00003 versus 4.73653 ±0.00006 days, and we measure a transit center time of 2457483.4310 ±0.0007, which is 42 minutes earlier than predicted. Using our new photometry, we precisely measure the density of the star KELT-11 to 4%. By combining the parallax and catalog magnitudes of the system, we are able to measure the radius of KELT-11b essentially empirically. Coupled with the stellar density, this gives a parallactic mass and radius of 1.8 Mand 2.9 R , which are each approximately 1σ higher than the adopted model-estimated mass and radius. If we conduct the same fit using the expected parallax uncertainty from the final Gaia data release, this difference increases to 4σ. The differences between the model and parallactic masses and radii for KELT-11 demonstrate the role that precise Gaia parallaxes, coupled with simultaneous photometric, radial velocity, and SED fitting, can play in determining stellar and planetary parameters. With high-precision photometry of transiting planets and high-precision Gaia parallaxes, the parallactic mass and radius uncertainties of stars become 1% and 3%, respectively. TESS is expected to discover 60-80 systems where these measurements will be possible. These parallactic mass and radius measurements have uncertainties small enough that they may provide observational input into the stellar models themselves.

Original languageEnglish (US)
Article number25
JournalAstronomical Journal
Volume154
Issue number1
DOIs
StatePublished - Jul 2017

Fingerprint

transit
stellar mass
radii
parallax
photometry
spectral energy distribution
radial velocity
catalogs
stars
Space Infrared Telescope Facility
stellar models
energy
planet
planets
orbitals
distribution

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Beatty, T. G., Stevens, D. J., Collins, K. A., Colón, K. D., James, D. J., Kreidberg, L., ... Kielkopf, J. F. (2017). Determining Empirical Stellar Masses and Radii from Transits and Gaia Parallaxes as Illustrated by Spitzer Observations of KELT-11b. Astronomical Journal, 154(1), [25]. https://doi.org/10.3847/1538-3881/aa7511
Beatty, Thomas G. ; Stevens, Daniel J. ; Collins, Karen A. ; Colón, Knicole D. ; James, David J. ; Kreidberg, Laura ; Pepper, Joshua ; Rodriguez, Joseph E. ; Siverd, Robert J. ; Stassun, Keivan G. ; Kielkopf, John F. / Determining Empirical Stellar Masses and Radii from Transits and Gaia Parallaxes as Illustrated by Spitzer Observations of KELT-11b. In: Astronomical Journal. 2017 ; Vol. 154, No. 1.
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abstract = "Using the Spitzer Space Telescope, we observed a transit at 3.6 μm of KELT-11b. We also observed three partial planetary transits from the ground. We simultaneously fit these observations, ground-based photometry from Pepper et al., radial velocity data from Pepper et al., and a spectral energy distribution (SED) model using catalog magnitudes and the Hipparcos parallax to the system. The only significant difference between our results and those of Pepper et al. is that we find the orbital period to be shorter by 37 s, 4.73610 ±0.00003 versus 4.73653 ±0.00006 days, and we measure a transit center time of 2457483.4310 ±0.0007, which is 42 minutes earlier than predicted. Using our new photometry, we precisely measure the density of the star KELT-11 to 4{\%}. By combining the parallax and catalog magnitudes of the system, we are able to measure the radius of KELT-11b essentially empirically. Coupled with the stellar density, this gives a parallactic mass and radius of 1.8 M⊙and 2.9 R⊙ , which are each approximately 1σ higher than the adopted model-estimated mass and radius. If we conduct the same fit using the expected parallax uncertainty from the final Gaia data release, this difference increases to 4σ. The differences between the model and parallactic masses and radii for KELT-11 demonstrate the role that precise Gaia parallaxes, coupled with simultaneous photometric, radial velocity, and SED fitting, can play in determining stellar and planetary parameters. With high-precision photometry of transiting planets and high-precision Gaia parallaxes, the parallactic mass and radius uncertainties of stars become 1{\%} and 3{\%}, respectively. TESS is expected to discover 60-80 systems where these measurements will be possible. These parallactic mass and radius measurements have uncertainties small enough that they may provide observational input into the stellar models themselves.",
author = "Beatty, {Thomas G.} and Stevens, {Daniel J.} and Collins, {Karen A.} and Col{\'o}n, {Knicole D.} and James, {David J.} and Laura Kreidberg and Joshua Pepper and Rodriguez, {Joseph E.} and Siverd, {Robert J.} and Stassun, {Keivan G.} and Kielkopf, {John F.}",
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Beatty, TG, Stevens, DJ, Collins, KA, Colón, KD, James, DJ, Kreidberg, L, Pepper, J, Rodriguez, JE, Siverd, RJ, Stassun, KG & Kielkopf, JF 2017, 'Determining Empirical Stellar Masses and Radii from Transits and Gaia Parallaxes as Illustrated by Spitzer Observations of KELT-11b', Astronomical Journal, vol. 154, no. 1, 25. https://doi.org/10.3847/1538-3881/aa7511

Determining Empirical Stellar Masses and Radii from Transits and Gaia Parallaxes as Illustrated by Spitzer Observations of KELT-11b. / Beatty, Thomas G.; Stevens, Daniel J.; Collins, Karen A.; Colón, Knicole D.; James, David J.; Kreidberg, Laura; Pepper, Joshua; Rodriguez, Joseph E.; Siverd, Robert J.; Stassun, Keivan G.; Kielkopf, John F.

In: Astronomical Journal, Vol. 154, No. 1, 25, 07.2017.

Research output: Contribution to journalArticle

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T1 - Determining Empirical Stellar Masses and Radii from Transits and Gaia Parallaxes as Illustrated by Spitzer Observations of KELT-11b

AU - Beatty, Thomas G.

AU - Stevens, Daniel J.

AU - Collins, Karen A.

AU - Colón, Knicole D.

AU - James, David J.

AU - Kreidberg, Laura

AU - Pepper, Joshua

AU - Rodriguez, Joseph E.

AU - Siverd, Robert J.

AU - Stassun, Keivan G.

AU - Kielkopf, John F.

PY - 2017/7

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N2 - Using the Spitzer Space Telescope, we observed a transit at 3.6 μm of KELT-11b. We also observed three partial planetary transits from the ground. We simultaneously fit these observations, ground-based photometry from Pepper et al., radial velocity data from Pepper et al., and a spectral energy distribution (SED) model using catalog magnitudes and the Hipparcos parallax to the system. The only significant difference between our results and those of Pepper et al. is that we find the orbital period to be shorter by 37 s, 4.73610 ±0.00003 versus 4.73653 ±0.00006 days, and we measure a transit center time of 2457483.4310 ±0.0007, which is 42 minutes earlier than predicted. Using our new photometry, we precisely measure the density of the star KELT-11 to 4%. By combining the parallax and catalog magnitudes of the system, we are able to measure the radius of KELT-11b essentially empirically. Coupled with the stellar density, this gives a parallactic mass and radius of 1.8 M⊙and 2.9 R⊙ , which are each approximately 1σ higher than the adopted model-estimated mass and radius. If we conduct the same fit using the expected parallax uncertainty from the final Gaia data release, this difference increases to 4σ. The differences between the model and parallactic masses and radii for KELT-11 demonstrate the role that precise Gaia parallaxes, coupled with simultaneous photometric, radial velocity, and SED fitting, can play in determining stellar and planetary parameters. With high-precision photometry of transiting planets and high-precision Gaia parallaxes, the parallactic mass and radius uncertainties of stars become 1% and 3%, respectively. TESS is expected to discover 60-80 systems where these measurements will be possible. These parallactic mass and radius measurements have uncertainties small enough that they may provide observational input into the stellar models themselves.

AB - Using the Spitzer Space Telescope, we observed a transit at 3.6 μm of KELT-11b. We also observed three partial planetary transits from the ground. We simultaneously fit these observations, ground-based photometry from Pepper et al., radial velocity data from Pepper et al., and a spectral energy distribution (SED) model using catalog magnitudes and the Hipparcos parallax to the system. The only significant difference between our results and those of Pepper et al. is that we find the orbital period to be shorter by 37 s, 4.73610 ±0.00003 versus 4.73653 ±0.00006 days, and we measure a transit center time of 2457483.4310 ±0.0007, which is 42 minutes earlier than predicted. Using our new photometry, we precisely measure the density of the star KELT-11 to 4%. By combining the parallax and catalog magnitudes of the system, we are able to measure the radius of KELT-11b essentially empirically. Coupled with the stellar density, this gives a parallactic mass and radius of 1.8 M⊙and 2.9 R⊙ , which are each approximately 1σ higher than the adopted model-estimated mass and radius. If we conduct the same fit using the expected parallax uncertainty from the final Gaia data release, this difference increases to 4σ. The differences between the model and parallactic masses and radii for KELT-11 demonstrate the role that precise Gaia parallaxes, coupled with simultaneous photometric, radial velocity, and SED fitting, can play in determining stellar and planetary parameters. With high-precision photometry of transiting planets and high-precision Gaia parallaxes, the parallactic mass and radius uncertainties of stars become 1% and 3%, respectively. TESS is expected to discover 60-80 systems where these measurements will be possible. These parallactic mass and radius measurements have uncertainties small enough that they may provide observational input into the stellar models themselves.

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