SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION
The recent detections of two transit events attributed to the super-Earth candidate K2-18b have provided the unprecedented prospect of spectroscopically studying a habitable-zone planet outside the solar system. Orbiting a nearby M2.5 dwarf and receiving virtually the same stellar insolation as Eart...
Main Authors: | , , , , , , , , , , , , , , , |
---|---|
Other Authors: | |
Language: | en |
Published: |
IOP PUBLISHING LTD
2017
|
Subjects: | |
Online Access: | http://hdl.handle.net/10150/624028 http://arizona.openrepository.com/arizona/handle/10150/624028 |
id |
ndltd-arizona.edu-oai-arizona.openrepository.com-10150-624028 |
---|---|
record_format |
oai_dc |
spelling |
ndltd-arizona.edu-oai-arizona.openrepository.com-10150-6240282017-06-10T03:00:44Z SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION Benneke, Björn Werner, Michael Petigura, Erik Knutson, Heather Dressing, Courtney Crossfield, Ian J. M. Schlieder, Joshua E. Livingston, John Beichman, Charles Christiansen, Jessie Krick, Jessica Gorjian, Varoujan Howard, Andrew W. Sinukoff, Evan Ciardi, David R. Akeson, Rachel L. Univ Arizona, Lunar & Planetary Lab astrobiology planets and satellites: detection planets and satellites: individual (K2-18b) techniques: photometric The recent detections of two transit events attributed to the super-Earth candidate K2-18b have provided the unprecedented prospect of spectroscopically studying a habitable-zone planet outside the solar system. Orbiting a nearby M2.5 dwarf and receiving virtually the same stellar insolation as Earth, K2-18b would be a prime candidate for the first detailed atmospheric characterization of a habitable-zone exoplanet using the Hubble Space Telescope (HST) and James Webb Space Telescope (JWST). Here, we report the detection of a third transit of K2-18b near the predicted transit time using the Spitzer Space Telescope. The Spitzer detection demonstrates the periodic nature of the two transit events discovered by K2, confirming that K2-18 is indeed orbited by a super-Earth in a 33 day orbit, ruling out the alternative scenario of two similarly sized, long-period planets transiting only once within the 75 day Kepler Space Telescope (K2) observation. We also find, however, that the transit event detected by Spitzer occurred 1.85 hr (7 sigma) before the predicted transit time. Our joint analysis of the Spitzer and K2 photometry reveals that this early occurrence of the transit is not caused by transit timing variations, but the result of an inaccurate ephemeris due to a previously undetected data anomaly in the K2 photometry. We refit the ephemeris and find that K2-18b would have been lost for future atmospheric characterizations with HST and JWST if we had not secured its ephemeris shortly after the discovery. We caution that immediate follow-up observations as presented here will also be critical for confirming and securing future planets discovered by the Transiting Exoplanet Survey Satellite (TESS), in particular if only two transit events are covered by the relatively short 27-day TESS campaigns. 2017-01-12 Article SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION 2017, 834 (2):187 The Astrophysical Journal 1538-4357 10.3847/1538-4357/834/2/187 http://hdl.handle.net/10150/624028 http://arizona.openrepository.com/arizona/handle/10150/624028 The Astrophysical Journal en http://stacks.iop.org/0004-637X/834/i=2/a=187?key=crossref.4113758b730f2803a70374cfb05d99cd © 2017. The American Astronomical Society. All rights reserved. IOP PUBLISHING LTD |
collection |
NDLTD |
language |
en |
sources |
NDLTD |
topic |
astrobiology planets and satellites: detection planets and satellites: individual (K2-18b) techniques: photometric |
spellingShingle |
astrobiology planets and satellites: detection planets and satellites: individual (K2-18b) techniques: photometric Benneke, Björn Werner, Michael Petigura, Erik Knutson, Heather Dressing, Courtney Crossfield, Ian J. M. Schlieder, Joshua E. Livingston, John Beichman, Charles Christiansen, Jessie Krick, Jessica Gorjian, Varoujan Howard, Andrew W. Sinukoff, Evan Ciardi, David R. Akeson, Rachel L. SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION |
description |
The recent detections of two transit events attributed to the super-Earth candidate K2-18b have provided the unprecedented prospect of spectroscopically studying a habitable-zone planet outside the solar system. Orbiting a nearby M2.5 dwarf and receiving virtually the same stellar insolation as Earth, K2-18b would be a prime candidate for the first detailed atmospheric characterization of a habitable-zone exoplanet using the Hubble Space Telescope (HST) and James Webb Space Telescope (JWST). Here, we report the detection of a third transit of K2-18b near the predicted transit time using the Spitzer Space Telescope. The Spitzer detection demonstrates the periodic nature of the two transit events discovered by K2, confirming that K2-18 is indeed orbited by a super-Earth in a 33 day orbit, ruling out the alternative scenario of two similarly sized, long-period planets transiting only once within the 75 day Kepler Space Telescope (K2) observation. We also find, however, that the transit event detected by Spitzer occurred 1.85 hr (7 sigma) before the predicted transit time. Our joint analysis of the Spitzer and K2 photometry reveals that this early occurrence of the transit is not caused by transit timing variations, but the result of an inaccurate ephemeris due to a previously undetected data anomaly in the K2 photometry. We refit the ephemeris and find that K2-18b would have been lost for future atmospheric characterizations with HST and JWST if we had not secured its ephemeris shortly after the discovery. We caution that immediate follow-up observations as presented here will also be critical for confirming and securing future planets discovered by the Transiting Exoplanet Survey Satellite (TESS), in particular if only two transit events are covered by the relatively short 27-day TESS campaigns. |
author2 |
Univ Arizona, Lunar & Planetary Lab |
author_facet |
Univ Arizona, Lunar & Planetary Lab Benneke, Björn Werner, Michael Petigura, Erik Knutson, Heather Dressing, Courtney Crossfield, Ian J. M. Schlieder, Joshua E. Livingston, John Beichman, Charles Christiansen, Jessie Krick, Jessica Gorjian, Varoujan Howard, Andrew W. Sinukoff, Evan Ciardi, David R. Akeson, Rachel L. |
author |
Benneke, Björn Werner, Michael Petigura, Erik Knutson, Heather Dressing, Courtney Crossfield, Ian J. M. Schlieder, Joshua E. Livingston, John Beichman, Charles Christiansen, Jessie Krick, Jessica Gorjian, Varoujan Howard, Andrew W. Sinukoff, Evan Ciardi, David R. Akeson, Rachel L. |
author_sort |
Benneke, Björn |
title |
SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION |
title_short |
SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION |
title_full |
SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION |
title_fullStr |
SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION |
title_full_unstemmed |
SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION |
title_sort |
spitzer observations confirm and rescue the habitable-zone super-earth k2-18b for future characterization |
publisher |
IOP PUBLISHING LTD |
publishDate |
2017 |
url |
http://hdl.handle.net/10150/624028 http://arizona.openrepository.com/arizona/handle/10150/624028 |
work_keys_str_mv |
AT bennekebjorn spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT wernermichael spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT petiguraerik spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT knutsonheather spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT dressingcourtney spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT crossfieldianjm spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT schliederjoshuae spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT livingstonjohn spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT beichmancharles spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT christiansenjessie spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT krickjessica spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT gorjianvaroujan spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT howardandreww spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT sinukoffevan spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT ciardidavidr spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization AT akesonrachell spitzerobservationsconfirmandrescuethehabitablezonesuperearthk218bforfuturecharacterization |
_version_ |
1718457484199329792 |