Daniel Apai

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Daniel Apai
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Prof. Daniel Apai
Born (1977-01-11) January 11, 1977 (age 47)
Szeged, Hungary
Citizenship United States of America, Hungarian
Alma mater Szeged University (Diploma) / University of Heidelberg (PhD)
Known for
Awards AAAS Fellow
Scientific career
Fields
Institutions
Doctoral advisor Thomas Henning
Doctoral students
  • Benjamin V. Rackham
  • Yifan Zhou
  • Kevin Wagner
  • Ben Wei Peng Lew
  • Alex Bixel
  • Jamie Dietrich
  • Rachael Amaro

Daniel Apai (born 1977) is an astrophysicist at The University of Arizona in Tucson, Arizona. He is known for his studies of astrobiology, extrasolar planets, planetary atmospheres, space telescope technology, and the formation of planetary systems. He is the principal investigator of the Earths in Other Solar Systems team of NASA's Nexus for Exoplanet System Studies and the Hubble Space Telescope Cloud Atlas Treasury program, and Project EDEN, a large survey for habitable planets in the immediate solar neighborhood. He is leading the Nautilus Space Observatory space telescope concept and co-leading the technology development underpinning it.

Contents

Career

Daniel Apai was born in Szeged, Hungary in 1977 and grew up in Budapest, Hungary. He studied physics at the University of Szeged, Hungary and the University of Jena, Germany, and received a diploma as research physicist in 2000. After graduation, he was awarded a German Academic Exchange Service Doctoral Fellowship and began his doctoral studies at the University of Jena, under the supervision of Thomas Henning on observational studies of young stars. In 2002 he moved to the Max Planck Institute for Astronomy, Heidelberg, Germany and he received his Ph.D. from the University of Heidelberg in 2004. In 2004 he was the recipient of the Patzer Price. Between 2004 and 2008 Daniel Apai has worked as a postdoctoral researcher at the Steward Observatory's NASA Astrobiology Institute node on high-contrast adaptive optics direct imaging searches for extrasolar planets. In 2008, Apai took on a position at the Space Telescope Science Institute as an assistant astronomer at the institute's Science Policy Group. In 2011, he moved back to faculty of the University of Arizona's Steward Observatory and Lunar and Planetary Laboratory, where he is full professor since 2021. He also held short-term visiting positions at The University of Texas, at the Max Planck Institute for Astronomy, Heidelberg, and at The University of Bern. In 2022, Apai became Interim Associate Dean for Research at the College of Science of the University of Arizona.

Work

Apai's work includes detailed comparative studies of planet formation around sun-like stars and low-mass stars; his team has discovered that the structure and evolution of protoplanetary disks depends on stellar mass. He used, for the first time, multi-epoch near-infrared radial velocity measurements to demonstrate that many O-type stars have massive companions at the time of their formation. Apai has also used the Hubble Space Telescope and the Spitzer Space Telescope to carry out pioneering observations to map condensate clouds in brown dwarf and exoplanet atmospheres. These studies demonstrated that brown dwarfs at the L- to T spectral type transition have clouds with varying thickness, [1] and that many brown dwarfs have zonal circulation and planetary-scale waves. [2] Daniel Apai was also a member of the team that [3] discovered and imaged the super-jupiter [3] Beta Pictoris b around the star Beta Pictoris.

Stellar Contamination of Exoplanet Transmission Spectra

In two papers published in 2018 [4] and 2019, [5] Apai, with his then-doctoral student Benjamin V. Rackham, and Mark Giampapa, provided the first systematic studies of the "transit light source effect" that leads to "stellar contamination" of exoplanet transmission spectra. These two terms were introduced in the studies to describe the impact of heterogeneous stellar photospheres on transit spectra of exoplanets. The papers correctly predicted that stellar contamination will be the limiting factor in the studies of small exoplanets with the James Webb Space Telescope.

Nautilus Space Observatory

In 2016, Apai assembled a group of optical scientists, astrophysicists, and aerospace engineers to address a key technological challenge to scaling up astronomical space telescopes, with the goal of proposing a novel space telescope to NASA to survey a thousand extrasolar planets for atmospheric signatures of life (biosignatures). This effort led to the successful development of a new optical technology, Multi-Order Diffractive Engineered Material (MODE) lenses, that combine refraction with diffraction to form high-quality images with an ultra-light optical element that can be cost-effectively fabricated. By replacing expensive and technologically challenging primary mirrors, the MODE technology has the potential to enable production of low-cost but large-aperture space telescopes. In an Astronomical Journal paper published in 2019 [6] , Apai and his team described a large and relatively low-cost array of identical unit telescopes that combines light incoherently, providing a light-collecting area equivalent of a single 50 m-diameter telescope. This concept is named the Nautilus Space Observatory (aka Nautilus Deep Space Observatory). With a light-collecting area about 100 times greater than that of the James Webb Space Telescope and ten times greater than that of the LUVOIR space telescope concept, Nautilus Deep Space Observatory is designed to survey extrasolar planets for biosignatures in a 10–100 times larger sample than other space telescope concepts yet envisioned. The first such unit space telescope, with a notional 8.5m-diameter lens, was proposed as the Nautilus Probe to the Astronomy 2020 Decadal Survey.

Publications and Books

Daniel Apai is an author of over 400 professional publications, including over 210 refereed papers. He co-edited (with Dante Lauretta) the book Protoplanetary Dust, published by Cambridge University Press.

Honours

In 2024, Apai was elected Fellow of the American Association for the Advancement of Science "For distinguished contributions to the field of astrobiology and astrophysics, particularly for advancements in our understanding of habitable exoplanets and planetary systems."

See also

Related Research Articles

<span class="mw-page-title-main">Exoplanet</span> Planet outside the Solar System

An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not then recognized as such. The first confirmation of the detection occurred in 1992. A different planet, first detected in 1988, was confirmed in 2003. As of 7 November 2024, there are 5,787 confirmed exoplanets in 4,320 planetary systems, with 969 systems having more than one planet. The James Webb Space Telescope (JWST) is expected to discover more exoplanets, and to give more insight into their traits, such as their composition, environmental conditions, and potential for life.

<span class="mw-page-title-main">Exomoon</span> Moon beyond the Solar System

An exomoon or extrasolar moon is a natural satellite that orbits an exoplanet or other non-stellar extrasolar body.

Gliese 581 is a red dwarf star of spectral type M3V which hosts a planetary system, 20.5 light-years away from Earth in the Libra constellation. Its estimated mass is about a third of that of the Sun, and it is the 101st closest known star system to the Sun. Gliese 581 is one of the oldest, least active M dwarfs known. Its low stellar activity improves the likelihood of its planets retaining significant atmospheres, and lessens the sterilizing impact of stellar flares.

<span class="mw-page-title-main">Hypothetical astronomical object</span> Astronomical bodies believed or speculated to exist

Various unknown astronomical objects have been hypothesized throughout recorded history. For example, in the 5th century BCE, the philosopher Philolaus defined a hypothetical astronomical object which he called the "Central Fire", around which he proposed other celestial bodies moved.

<span class="mw-page-title-main">Methods of detecting exoplanets</span>

Any planet is an extremely faint light source compared to its parent star. For example, a star like the Sun is about a billion times as bright as the reflected light from any of the planets orbiting it. In addition to the intrinsic difficulty of detecting such a faint light source, the light from the parent star causes a glare that washes it out. For those reasons, very few of the exoplanets reported as of January 2024 have been observed directly, with even fewer being resolved from their host star.

WASP-2 is a binary star system in the Delphinus constellation located about 500 light-years away. The primary is magnitude 12 orange dwarf star, orbited by red dwarf star on wide orbit. The star system shows an infrared excess noise of unknown origin.

<span class="mw-page-title-main">Beta Pictoris b</span> Super Jupiter orbiting Beta Pictoris

Beta Pictoris b (abbreviated as β Pic b) is an exoplanet orbiting the young debris disk A-type main sequence star Beta Pictoris located approximately 63 light-years (19.4 parsecs, or 6×1014 km) away from Earth in the constellation of Pictor. It has a mass around 13 Jupiter masses and a radius around 46% larger than Jupiter's. It orbits at 9 AU from Beta Pictoris, which is about 3.5 times farther than the orbit of Beta Pictoris c. It orbits close to the plane of the debris disk orbiting the star, with a low eccentricity and a period of 20–21 years.

<span class="mw-page-title-main">Exocomet</span> Comet outside the Solar System

An exocomet, or extrasolar comet, is a comet outside the Solar System, which includes rogue comets and comets that orbit stars other than the Sun. The first exocomets were detected in 1987 around Beta Pictoris, a very young A-type main-sequence star. There are now a total of 27 stars around which exocomets have been observed or suspected.

<span class="mw-page-title-main">Technosignature</span> Property that provides scientific evidence for the presence of technology

Technosignature or technomarker is any measurable property or effect that provides scientific evidence of past or present technology. Technosignatures are analogous to biosignatures, which signal the presence of life, whether intelligent or not. Some authors prefer to exclude radio transmissions from the definition, but such restrictive usage is not widespread. Jill Tarter has proposed that the search for extraterrestrial intelligence (SETI) be renamed "the search for technosignatures". Various types of technosignatures, such as radiation leakage from megascale astroengineering installations such as Dyson spheres, the light from an extraterrestrial ecumenopolis, or Shkadov thrusters with the power to alter the orbits of stars around the Galactic Center, may be detectable with hypertelescopes. Some examples of technosignatures are described in Paul Davies's 2010 book The Eerie Silence, although the terms "technosignature" and "technomarker" do not appear in the book.

<span class="mw-page-title-main">PSO J318.5−22</span> Extrasolar free-floating planet

PSO J318.5−22 is an extrasolar object of planetary mass that does not orbit a parent star, it is an analog to directly imaged young gas giants. There is no consensus yet among astronomers whether the object should be referred to as a sub-brown dwarf, as a rogue planet or as a young brown dwarf. It is approximately 80 light-years away and belongs to the Beta Pictoris moving group. The object was discovered in 2013 in images taken by the Pan-STARRS PS1 wide-field telescope. PSO J318.5-22's age is inferred to be 23 million years, the same age as the Beta Pictoris moving group. Based on its calculated temperature and age, it is classified under the brown dwarf spectral type L7.

<span class="mw-page-title-main">Next-Generation Transit Survey</span> Ground-based robotic search for exoplanets

The Next-Generation Transit Survey (NGTS) is a ground-based robotic search for exoplanets. The facility is located at Paranal Observatory in the Atacama Desert in northern Chile, about 2 km from ESO's Very Large Telescope and 0.5 km from the VISTA Survey Telescope. Science operations began in early 2015. The astronomical survey is managed by a consortium of seven European universities and other academic institutions from Chile, Germany, Switzerland, and the United Kingdom. Prototypes of the array were tested in 2009 and 2010 on La Palma, and from 2012 to 2014 at Geneva Observatory.

The Virtual Planetary Laboratory (VPL) is a virtual institute based at the University of Washington that studies how to detect exoplanetary habitability and their potential biosignatures. First formed in 2001, the VPL is part of the NASA Astrobiology Institute (NAI) and connects more than fifty researchers at twenty institutions together in an interdisciplinary effort. VPL is also part of the Nexus for Exoplanet System Science (NExSS) network, with principal investigator Victoria Meadows leading the NExSS VPL team.

The Carl Sagan Institute: Pale Blue Dot and Beyond was founded in 2014 at Cornell University in Ithaca, New York to further the search for habitable planets and moons in and outside the Solar System. It is focused on the characterization of exoplanets and the instruments to search for signs of life in the universe. The founder and current director of the institute is astronomer Lisa Kaltenegger.

<span class="mw-page-title-main">TRAPPIST-1</span> Ultra-cool red dwarf star in the constellation Aquarius

TRAPPIST-1 is a cool red dwarf star with seven known exoplanets. It lies in the constellation Aquarius about 40.66 light-years away from Earth, and has a surface temperature of about 2,566 K. Its radius is slightly larger than Jupiter and it has a mass of about 9% of the Sun. It is estimated to be 7.6 billion years old, making it older than the Solar System. The discovery of the star was first published in 2000.

<span class="mw-page-title-main">Habitable Exoplanets Observatory</span> Proposed space observatory to characterize exoplanets atmospheres

The Habitable Exoplanet Observatory (HabEx) is a space telescope concept that would be optimized to search for and image Earth-size habitable exoplanets in the habitable zones of their stars, where liquid water can exist. HabEx would aim to understand how common terrestrial worlds beyond the Solar System may be and determine the range of their characteristics. It would be an optical, UV and infrared telescope that would also use spectrographs to study planetary atmospheres and eclipse starlight with either an internal coronagraph or an external starshade.

Nautilus Deep Space Observatory (NDSO) is a proposed deep space fleet of space telescopes designed to search for biosignatures of life in the atmospheres of exoplanets.

K2-315b is an exoplanet located 185.3 light years away from Earth in the southern zodiac constellation Libra. It orbits the red dwarf K2-315.

TOI-1452 b is a confirmed super-Earth exoplanet, possibly a water world, orbiting a red-dwarf star TOI-1452 about 100 light-years away in the Draco constellation. The exoplanet is about 70% larger in diameter than Earth, and roughly five times as massive.

References

  1. ↑ Apai, Daniel; Radigan, Jacqueline & Buenzli, Esther (2013). "HST Spectral Mapping of L/T Transition Brown Dwarfs Reveals Cloud Thickness Variations". The Astrophysical Journal . 768 (2): 121–136. arXiv: 1303.4151 . Bibcode:2013ApJ...768..121A. doi:10.1088/0004-637X/768/2/121. S2CID   118861458.
  2. ↑ Apai, Daniel; Karalidi, Theodora & Marley, M. S. (2017). "Zones, spots, and planetary-scale waves beating in brown dwarf atmospheres". Science . 357 (6352): 683–687. Bibcode:2017Sci...357..683A. doi: 10.1126/science.aam9848 . PMID   28818943.
  3. 1 2 Lagrange, Anne-Marie; Bonnefoy, Mickael; Chauvin, G. & Apai, Daniel (2010). "A Giant Planet Imaged in the Disk of the Young Star β Pictoris". Science . 329 (5987): 57–61. arXiv: 1006.3314 . Bibcode:2010Sci...329...57L. doi:10.1126/science.1187187. PMID   20538914.
  4. ↑ Rackham, Benjamin V.; Apai, Daniel & Giampapa, M. (2018). "The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets". The Astrophysical Journal . 853 (122): 683–687. arXiv: 1711.05691 . Bibcode:2018ApJ...853..122R. doi: 10.3847/1538-4357/aaa08c .
  5. ↑ Rackham, Benjamin V.; Apai, Daniel & Giampapa, M. (2019). "The Transit Light Source Effect. II. The Impact of Stellar Heterogeneity on Transmission Spectra of Planets Orbiting Broadly Sun-like Stars". The Astronomical Journal . 157 (3): 1–23. arXiv: 1812.06184 . Bibcode:2019AJ....157...96R. doi: 10.3847/1538-3881/aaf892 .
  6. ↑ Apai, Daniel; Milster, Tom D.; Kim, Daewook; Bixel, Alex; Schneider, Glenn; Ling, Ronguang & Arenberg, Jonathan (2019). "A Thousand Earths: A Very Large Aperture, Ultralight Space Telescope Array for Atmospheric Biosignature Surveys". Astronomical Journal . 158 (2): 1–21. arXiv: 1906.05079 . Bibcode:2019AJ....158...83A. doi: 10.3847/1538-3881/ab2631 .
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