Direct measurement of stellar angular diameters by the VERITAS Cherenkov telescopes

W. Benbow, R. Bird, A. Brill, R. Brose, A. J. Chromey, M. K. Daniel, Q. Feng, J. P. Finley, Lucy F Fortson, A. Furniss, G. H. Gillanders, C. Giuri, O. Gueta, D. Hanna, J. P. Halpern, T. Hassan, J. Holder, G. Hughes, T. B. Humensky, A. M. JoyceP. Kaaret, P. Kar, N. Kelley-Hoskins, M. Kertzman, D. Kieda, M. Krause, M. J. Lang, T. T.Y. Lin, G. Maier, N. Matthews, P. Moriarty, R. Mukherjee, D. Nieto, M. Nievas-Rosillo, S. O’Brien, R. A. Ong, N. Park, A. Petrashyk, M. Pohl, E. Pueschel, J. Quinn, K. Ragan, P. T. Reynolds, G. T. Richards, E. Roache, C. Rulten, I. Sadeh, M. Santander, G. H. Sembroski, K. Shahinyan, I. Sushch, S. P. Wakely, R. M. Wells, P. Wilcox, A. Wilhelm, D. A. Williams, T. J. Williamson

Research output: Contribution to journalLetter

2 Citations (Scopus)

Abstract

The angular size of a star is a critical factor in determining its basic properties1. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging telescope. This fundamental limitation can be overcome by studying the diffraction pattern in the shadow cast when an asteroid occults a star2, but only when the photometric uncertainty is smaller than the noise added by atmospheric scintillation3. Atmospheric Cherenkov telescopes used for particle astrophysics observations have not generally been exploited for optical astronomy due to the modest optical quality of the mirror surface. However, their large mirror area makes them well suited for such high-time-resolution precision photometry measurements4. Here we report two occultations of stars observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS)5 Cherenkov telescopes with millisecond sampling, from which we are able to provide a direct measurement of the occulted stars’ angular diameter at the ≤0.1 mas scale. This is a resolution never achieved before with optical measurements and represents an order of magnitude improvement over the equivalent lunar occultation method6. We compare the resulting stellar radius with empirically derived estimates from temperature and brightness measurements, confirming the latter can be biased for stars with ambiguous stellar classifications.

Original languageEnglish (US)
Pages (from-to)511-516
Number of pages6
JournalNature Astronomy
Volume3
Issue number6
DOIs
StatePublished - Jun 1 2019

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telescopes
stars
radiation
lunar occultation
mirrors
occultation
asteroids
astronomy
optical measurement
photometry
temperature measurement
casts
astrophysics
brightness
diffraction patterns
sampling
radii
estimates

Cite this

Benbow, W., Bird, R., Brill, A., Brose, R., Chromey, A. J., Daniel, M. K., ... Williamson, T. J. (2019). Direct measurement of stellar angular diameters by the VERITAS Cherenkov telescopes. Nature Astronomy, 3(6), 511-516. https://doi.org/10.1038/s41550-019-0741-z

Direct measurement of stellar angular diameters by the VERITAS Cherenkov telescopes. / Benbow, W.; Bird, R.; Brill, A.; Brose, R.; Chromey, A. J.; Daniel, M. K.; Feng, Q.; Finley, J. P.; Fortson, Lucy F; Furniss, A.; Gillanders, G. H.; Giuri, C.; Gueta, O.; Hanna, D.; Halpern, J. P.; Hassan, T.; Holder, J.; Hughes, G.; Humensky, T. B.; Joyce, A. M.; Kaaret, P.; Kar, P.; Kelley-Hoskins, N.; Kertzman, M.; Kieda, D.; Krause, M.; Lang, M. J.; Lin, T. T.Y.; Maier, G.; Matthews, N.; Moriarty, P.; Mukherjee, R.; Nieto, D.; Nievas-Rosillo, M.; O’Brien, S.; Ong, R. A.; Park, N.; Petrashyk, A.; Pohl, M.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Rulten, C.; Sadeh, I.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Sushch, I.; Wakely, S. P.; Wells, R. M.; Wilcox, P.; Wilhelm, A.; Williams, D. A.; Williamson, T. J.

In: Nature Astronomy, Vol. 3, No. 6, 01.06.2019, p. 511-516.

Research output: Contribution to journalLetter

Benbow, W, Bird, R, Brill, A, Brose, R, Chromey, AJ, Daniel, MK, Feng, Q, Finley, JP, Fortson, LF, Furniss, A, Gillanders, GH, Giuri, C, Gueta, O, Hanna, D, Halpern, JP, Hassan, T, Holder, J, Hughes, G, Humensky, TB, Joyce, AM, Kaaret, P, Kar, P, Kelley-Hoskins, N, Kertzman, M, Kieda, D, Krause, M, Lang, MJ, Lin, TTY, Maier, G, Matthews, N, Moriarty, P, Mukherjee, R, Nieto, D, Nievas-Rosillo, M, O’Brien, S, Ong, RA, Park, N, Petrashyk, A, Pohl, M, Pueschel, E, Quinn, J, Ragan, K, Reynolds, PT, Richards, GT, Roache, E, Rulten, C, Sadeh, I, Santander, M, Sembroski, GH, Shahinyan, K, Sushch, I, Wakely, SP, Wells, RM, Wilcox, P, Wilhelm, A, Williams, DA & Williamson, TJ 2019, 'Direct measurement of stellar angular diameters by the VERITAS Cherenkov telescopes', Nature Astronomy, vol. 3, no. 6, pp. 511-516. https://doi.org/10.1038/s41550-019-0741-z
Benbow W, Bird R, Brill A, Brose R, Chromey AJ, Daniel MK et al. Direct measurement of stellar angular diameters by the VERITAS Cherenkov telescopes. Nature Astronomy. 2019 Jun 1;3(6):511-516. https://doi.org/10.1038/s41550-019-0741-z
Benbow, W. ; Bird, R. ; Brill, A. ; Brose, R. ; Chromey, A. J. ; Daniel, M. K. ; Feng, Q. ; Finley, J. P. ; Fortson, Lucy F ; Furniss, A. ; Gillanders, G. H. ; Giuri, C. ; Gueta, O. ; Hanna, D. ; Halpern, J. P. ; Hassan, T. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Joyce, A. M. ; Kaaret, P. ; Kar, P. ; Kelley-Hoskins, N. ; Kertzman, M. ; Kieda, D. ; Krause, M. ; Lang, M. J. ; Lin, T. T.Y. ; Maier, G. ; Matthews, N. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Nievas-Rosillo, M. ; O’Brien, S. ; Ong, R. A. ; Park, N. ; Petrashyk, A. ; Pohl, M. ; Pueschel, E. ; Quinn, J. ; Ragan, K. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Rulten, C. ; Sadeh, I. ; Santander, M. ; Sembroski, G. H. ; Shahinyan, K. ; Sushch, I. ; Wakely, S. P. ; Wells, R. M. ; Wilcox, P. ; Wilhelm, A. ; Williams, D. A. ; Williamson, T. J. / Direct measurement of stellar angular diameters by the VERITAS Cherenkov telescopes. In: Nature Astronomy. 2019 ; Vol. 3, No. 6. pp. 511-516.
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abstract = "The angular size of a star is a critical factor in determining its basic properties1. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging telescope. This fundamental limitation can be overcome by studying the diffraction pattern in the shadow cast when an asteroid occults a star2, but only when the photometric uncertainty is smaller than the noise added by atmospheric scintillation3. Atmospheric Cherenkov telescopes used for particle astrophysics observations have not generally been exploited for optical astronomy due to the modest optical quality of the mirror surface. However, their large mirror area makes them well suited for such high-time-resolution precision photometry measurements4. Here we report two occultations of stars observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS)5 Cherenkov telescopes with millisecond sampling, from which we are able to provide a direct measurement of the occulted stars’ angular diameter at the ≤0.1 mas scale. This is a resolution never achieved before with optical measurements and represents an order of magnitude improvement over the equivalent lunar occultation method6. We compare the resulting stellar radius with empirically derived estimates from temperature and brightness measurements, confirming the latter can be biased for stars with ambiguous stellar classifications.",
author = "W. Benbow and R. Bird and A. Brill and R. Brose and Chromey, {A. J.} and Daniel, {M. K.} and Q. Feng and Finley, {J. P.} and Fortson, {Lucy F} and A. Furniss and Gillanders, {G. H.} and C. Giuri and O. Gueta and D. Hanna and Halpern, {J. P.} and T. Hassan and J. Holder and G. Hughes and Humensky, {T. B.} and Joyce, {A. M.} and P. Kaaret and P. Kar and N. Kelley-Hoskins and M. Kertzman and D. Kieda and M. Krause and Lang, {M. J.} and Lin, {T. T.Y.} and G. Maier and N. Matthews and P. Moriarty and R. Mukherjee and D. Nieto and M. Nievas-Rosillo and S. O’Brien and Ong, {R. A.} and N. Park and A. Petrashyk and M. Pohl and E. Pueschel and J. Quinn and K. Ragan and Reynolds, {P. T.} and Richards, {G. T.} and E. Roache and C. Rulten and I. Sadeh and M. Santander and Sembroski, {G. H.} and K. Shahinyan and I. Sushch and Wakely, {S. P.} and Wells, {R. M.} and P. Wilcox and A. Wilhelm and Williams, {D. A.} and Williamson, {T. J.}",
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AU - Benbow, W.

AU - Bird, R.

AU - Brill, A.

AU - Brose, R.

AU - Chromey, A. J.

AU - Daniel, M. K.

AU - Feng, Q.

AU - Finley, J. P.

AU - Fortson, Lucy F

AU - Furniss, A.

AU - Gillanders, G. H.

AU - Giuri, C.

AU - Gueta, O.

AU - Hanna, D.

AU - Halpern, J. P.

AU - Hassan, T.

AU - Holder, J.

AU - Hughes, G.

AU - Humensky, T. B.

AU - Joyce, A. M.

AU - Kaaret, P.

AU - Kar, P.

AU - Kelley-Hoskins, N.

AU - Kertzman, M.

AU - Kieda, D.

AU - Krause, M.

AU - Lang, M. J.

AU - Lin, T. T.Y.

AU - Maier, G.

AU - Matthews, N.

AU - Moriarty, P.

AU - Mukherjee, R.

AU - Nieto, D.

AU - Nievas-Rosillo, M.

AU - O’Brien, S.

AU - Ong, R. A.

AU - Park, N.

AU - Petrashyk, A.

AU - Pohl, M.

AU - Pueschel, E.

AU - Quinn, J.

AU - Ragan, K.

AU - Reynolds, P. T.

AU - Richards, G. T.

AU - Roache, E.

AU - Rulten, C.

AU - Sadeh, I.

AU - Santander, M.

AU - Sembroski, G. H.

AU - Shahinyan, K.

AU - Sushch, I.

AU - Wakely, S. P.

AU - Wells, R. M.

AU - Wilcox, P.

AU - Wilhelm, A.

AU - Williams, D. A.

AU - Williamson, T. J.

PY - 2019/6/1

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N2 - The angular size of a star is a critical factor in determining its basic properties1. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging telescope. This fundamental limitation can be overcome by studying the diffraction pattern in the shadow cast when an asteroid occults a star2, but only when the photometric uncertainty is smaller than the noise added by atmospheric scintillation3. Atmospheric Cherenkov telescopes used for particle astrophysics observations have not generally been exploited for optical astronomy due to the modest optical quality of the mirror surface. However, their large mirror area makes them well suited for such high-time-resolution precision photometry measurements4. Here we report two occultations of stars observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS)5 Cherenkov telescopes with millisecond sampling, from which we are able to provide a direct measurement of the occulted stars’ angular diameter at the ≤0.1 mas scale. This is a resolution never achieved before with optical measurements and represents an order of magnitude improvement over the equivalent lunar occultation method6. We compare the resulting stellar radius with empirically derived estimates from temperature and brightness measurements, confirming the latter can be biased for stars with ambiguous stellar classifications.

AB - The angular size of a star is a critical factor in determining its basic properties1. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging telescope. This fundamental limitation can be overcome by studying the diffraction pattern in the shadow cast when an asteroid occults a star2, but only when the photometric uncertainty is smaller than the noise added by atmospheric scintillation3. Atmospheric Cherenkov telescopes used for particle astrophysics observations have not generally been exploited for optical astronomy due to the modest optical quality of the mirror surface. However, their large mirror area makes them well suited for such high-time-resolution precision photometry measurements4. Here we report two occultations of stars observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS)5 Cherenkov telescopes with millisecond sampling, from which we are able to provide a direct measurement of the occulted stars’ angular diameter at the ≤0.1 mas scale. This is a resolution never achieved before with optical measurements and represents an order of magnitude improvement over the equivalent lunar occultation method6. We compare the resulting stellar radius with empirically derived estimates from temperature and brightness measurements, confirming the latter can be biased for stars with ambiguous stellar classifications.

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