Searching for Planets around Altair with JWST/NIRcam

Tiffany Meshkat; Charles Beichman; Jorge Llop-Sayson; Geoffrey Bryden; Alexandra Z. Greenbaum; Eric E. Mamajek; Marie Ygouf; Julien Girard; Jarron Leisenring; Aniket Sanghi; Marshall Perrin; Michael Meyer; Laurent Pueyo; William Balmer; András Gáspár; Klaus Hodapp

doi:10.3847/1538-3881/aeac14

AI summary · arXiv: 2611.13132v1 · astro-ph.EP

Searching for Planets around Altair with JWST/NIRcam

Tiffany Meshkat, Charles Beichman, Jorge Llop-Sayson, Geoffrey Bryden, Alexandra Z. Greenbaum, Eric E. Mamajek, Marie Ygouf, Julien Girard,

and 8 more authors

Jarron Leisenring, Aniket Sanghi, Marshall Perrin, Michael Meyer, Laurent Pueyo, William Balmer, András Gáspár, Klaus Hodapp

Original paper · DOI 10.3847/1538-3881/aeac14 Submitted to arXiv on 09 Nov. 2026 T. Meshkat et al. 2026 AJ 172 280 14 pages, 4 figures, published in AJ License: CC BY 4.0

How to read this summary? Illustrated guide

The essentials

Two-epoch JWST/NIRCam imaging found no co-moving companions around Altair and established sub-Saturn-mass sensitivity beyond about 10 au under the adopted models.

Question

Can deep coronagraphic imaging detect giant planets around young, nearby Altair, and are the point sources in its field physically associated with the star? The study also assesses whether Altair could serve as a reference star for future imaging.

Method

The authors obtained two epochs of simultaneous F444W and F200W NIRCam coronagraphic observations, in October 2024 and May 2025, with 8,364 seconds of on-sky integration per epoch. They processed the data with ADI, RDI using Vega, and combined ADI+RDI KLIP reductions, then used injected-companion tests to calibrate contrast limits and Sonora Flame Skimmer models to estimate planet masses. The second epoch and color measurements were used to test candidate sources for common proper motion.

Findings

Result The observations reached F444W contrasts of 1.5 × 10^-7 at 2 arcsec and a few × 10^-8 beyond 4 arcsec.
See the passage in the paper
We observed Altair with the JWST/NIRCam coronagraph in F444W and F200W, achieving contrast levels of $1.5\times 10^{-7}$ at 2” (10 au) and a few $\times 10^{-8}$ beyond 4” (20 au).
Result Under the adopted Sonora Flame Skimmer model and Altair age, the mass limits reach sub-Saturn masses beyond 10 au.
See the passage in the paper
Using its recently revised age of 88$\pm$10 Myr [64] and the Sonora Flame Skimmer model [46], this corresponds to sub-Saturn mass limits beyond 10 au.
Result The candidate sources identified in the first epoch were not confirmed as companions; their motion and colors support their identification as background stars.
See the passage in the paper
Second epoch observations showed these candidates were not co-moving with Altair, and their colors consistent with background stars.
Authors’ interpretation The authors conclude that Altair is not associated with any known stellar association and that the listed WDS entries are background stars rather than physical companions.
See the passage in the paper
The companions WDS 19508+0852B through G all have parallaxes and proper motions consistent with being distant ($>0.4$ kpc) background stars, and we conclude that none of the WDS entries associated with Altair are physical companions.
Authors’ interpretation The authors argue that Altair’s nearby background-star field makes it a useful potential reference target for future coronagraphic imaging.
See the passage in the paper
We also characterize the background star field around Altair and find that it will remain a few arcsec from any background sources over the coming decade, making it a reliable reference star for future coronagraphic imaging campaigns, particularly for the Roman Coronagraph Instrument.

Limitations

The planet-mass sensitivity depends on atmospheric assumptions, including metallicity, vertical mixing, C/O ratio, and clouds.
See the passage in the paper
The conversion of the F444W contrast curve to a planetary mass sensitivity curve relies on the use of atmospheric and evolutionary models and requires assumptions to be made about the planet’s atmospheric parameters, such as metallicity, vertical mixing strength, C/O ratio, and the presence/absence of clouds.
F200W coverage was restricted to one side of Altair in each epoch, limiting where that filter could help distinguish candidate companions from background sources.
See the passage in the paper
By observing Altair in both F444W and F200W, we were able to reject out any detected sources as background stars, since stars are significantly brighter in 2 $\mu$m than in 4.44 $\mu$m. However, since the M430R mask only covers one half of the sky in F200W, we only can rule out detected companions to the south of F444W (see Figure 1).
The search does not exclude all planets at small separations; the authors note that planets below 1–2 Jupiter masses may remain within 10 au.
See the passage in the paper
Based on planet occurrence rates and mass functions presented in Meyer et al. [52], even with a null detection in our deep dataset, $<1-2M_{\rm Jup}$ planets may still reside within 10 au where occurrence rates are expected to be higher.

Why it matters

The authors present Altair as a compelling target for continued high-contrast imaging because its revised young age and proximity enable sensitive searches for low-mass giant planets. They also characterize its nearby background sources to support possible use of Altair as a reference star, including for future Roman Coronagraph Instrument observations.

Written by AI from the paper. Passages are checked word for word against the text we analysed; the rest may contain errors.

AI-generated keywords: Altair; JWST/NIRCam; direct imaging; giant planets; high-contrast observations

Read further

Comprehensive Summary
Layman's Summary
Blog article
Original abstract

The paper reports a search for giant planets around Altair using two epochs of JWST/NIRCam coronagraphic imaging. Located just 5.13 parsecs from Earth, Altair has a recently estimated age of 88 ± 10 million years based on two-dimensional stellar modeling. Its proximity and youth make it a promising direct-imaging target, although its rapid rotation complicates conventional radial-velocity searches. The study investigates whether planets can be detected at wide separations and whether Altair’s surrounding field makes it a suitable reference target for future high-contrast observations. The team observed Altair on October 11, 2024, and May 26, 2025, with NIRCam’s MASK430R coronagraph using the F444W and F200W filters. Each epoch included two telescope roll angles separated by about eight degrees, with approximately 8,364 seconds of total on-sky exposure. The team also observed Vega to obtain a reference point-spread function. They processed the data using angular differential imaging, reference differential imaging, and a combination of both, with the KLIP subtraction algorithm. Detection limits were estimated from the processed images and calibrated using artificial companions injected into the data to account for signal losses and coronagraph throughput. F200W-to-F444W colors and changes in apparent position between epochs helped distinguish potential planets from background stars. The observations achieved F444W contrasts of about 2 × 10⁻⁶ at one arcsecond, 1.5 × 10⁻⁷ at two arcseconds, and a few × 10⁻⁸ beyond four arcseconds. At Altair’s distance, these separations correspond to approximately 5, 10, and 20 astronomical units. Using the Sonora Flame Skimmer planetary models, the authors infer sensitivity to sub-Jupiter-mass planets beyond roughly 5 au and sub-Saturn-mass planets beyond about 10 au. A representative model reaches approximately 0.7 Saturn masses in the outer field. These mass estimates depend on assumptions about planetary atmospheres. The authors find that higher metallicity weakens the inferred mass sensitivity, although their model comparisons still indicate sensitivity to planets below one Jupiter mass beyond about two arcseconds. The models do not include water-ice clouds, which could further reduce a planet’s F444W brightness. Several point sources appeared in the first-epoch images. Northern sources could not be checked using F200W data from that epoch because the filter’s field coverage behind the mask was limited. Second-epoch observations showed that the candidates did not share Altair’s motion. Their apparent relative motion—typically 0.64–0.76 arcseconds over about 7.5 months—and, where available, their colors were consistent with stationary background stars. The study therefore found no confirmed planetary companions. One faint source detected only once remains unconstrained, but it is not a confirmed companion. The authors report no detected debris disk and find no convincing association between Altair and a known stellar group. Its listed wide companions are background stars. The null result does not rule out planets, particularly within about 10 au, where the observations are less sensitive and planet occurrence may be higher. Altair’s youth and proximity nevertheless make it a valuable target for future imaging. The authors characterize 11 field sources and estimate that none will pass within about 3.1 arcseconds of Altair, supporting its possible use as a future reference star, including for Roman observations. However, Altair’s stellar diameter of roughly 3–3.7 milliarcseconds exceeds the cited ideal size for Roman reference stars. Its suitability will therefore depend on whether partial resolution limits its use.

JWST Finds No Confirmed Planets Around Altair—but Shows What It Could Detect

Altair is one of the Sun’s nearest stellar neighbors, only 5.13 parsecs—about 16.7 light-years—away. It is also young by stellar standards: recent two-dimensional modeling estimates its age at 88 ± 10 million years. Those qualities make it an appealing place to look for giant planets while they are still young and potentially bright. But Altair spins rapidly, complicating the radial-velocity technique often used to find planets.

In Searching for Planets around Altair with JWST/NIRcam, Tiffany Meshkat, Charles Beichman, Jorge Llop-Sayson, Geoffrey Bryden, Alexandra Z. Greenbaum, Eric E. Mamajek et al. report a search using JWST’s NIRCam instrument. The observations found no confirmed planets, but they demonstrate the telescope’s sensitivity to faint worlds at wide distances from the star—and examine whether Altair’s surrounding field could be useful for future high-contrast observations.

Looking for faint companions

The team observed Altair on October 11, 2024, and May 26, 2025, using NIRCam’s MASK430R coronagraph. A coronagraph blocks much of a star’s glare, helping astronomers look for dim objects nearby. The observations used the F444W and F200W filters, which capture light at different infrared wavelengths. At each epoch, the telescope observed Altair at two roll angles, separated by about eight degrees. The total on-sky exposure time was approximately 8,364 seconds.

The researchers also observed Vega to provide a reference image of a star’s point-spread function—the pattern of light produced by the telescope and instrument. They processed the images using angular differential imaging, reference differential imaging, and a combination of both, with the KLIP algorithm to subtract the star’s light and reveal potential companions.

To estimate how faint a planet the observations could have detected, the team inserted artificial companions into the data and measured how much of their light survived the image processing. This calibration accounts for both the coronagraph’s effects and signal lost during subtraction. The team then used infrared colors and the apparent movement of sources between observing dates to help distinguish planets orbiting Altair from unrelated background stars.

How sensitive were the observations?

The observations reached a F444W contrast of about 2 × 10-6 at one arcsecond from Altair, improving to about 1.5 × 10-7 at two arcseconds. Beyond four arcseconds, the contrast reached a few × 10-8. Because Altair is so close, one, two, and four arcseconds correspond roughly to 5, 10, and 20 astronomical units, respectively. An astronomical unit is the average distance between Earth and the Sun.

Using the Sonora Flame Skimmer planetary models, the authors estimate that the data could detect sub-Jupiter-mass planets beyond roughly 5 au and sub-Saturn-mass planets beyond about 10 au. In one representative model, sensitivity reaches about 0.7 Saturn masses in the outer field. These estimates are not direct measurements: they depend on assumptions about how a planet’s atmosphere emits infrared light.

Atmospheric composition matters. Higher metallicity makes a planet appear dimmer in the models, weakening the inferred mass sensitivity. The models also do not include water-ice clouds, which could further reduce a planet’s brightness in F444W. Even with these uncertainties, the model comparisons indicate sensitivity to planets below one Jupiter mass beyond about two arcseconds.

Background stars, not planets

Several point sources appeared in the first-epoch images. Some northern sources could not be checked with F200W data from that epoch because the filter’s coverage behind the coronagraph mask was limited. The second set of observations provided a crucial test: a planet should move across the sky with Altair, while a distant background star would appear to shift relative to it as Altair moves.

The candidates did not share Altair’s motion. Over about 7.5 months, their apparent relative shifts were typically 0.64–0.76 arcseconds. Where the team could measure colors, those too were consistent with background stars. The study therefore reports no confirmed planetary companions. One faint source was detected only once and remains unconstrained; it is not a confirmed companion.

A useful target for future observations

The null result does not rule out planets around Altair. The search was less sensitive within about 10 au, where planets may also be more common. The team detected no debris disk and found no convincing association between Altair and a known stellar group. Its listed wide companions are background stars.

Altair may still be valuable beyond this planet search. The authors characterize 11 sources in its field and estimate that none will pass within about 3.1 arcseconds of the star. That relative emptiness could make Altair a useful reference target for future high-contrast observations, including with the Roman Space Telescope.

There is a complication: Altair’s diameter is roughly 3–3.7 milliarcseconds, larger than the cited ideal size for Roman reference stars. Whether its partially resolved disk would limit its usefulness remains uncertain. For now, the study leaves Altair as a promising but challenging target: a nearby, youthful star where future observations may continue probing for worlds that current data cannot yet reveal.

Created on 11 Nov. 2026

Was this synthesis useful?

Score: 0

Ask questions about this paper to our AI assistant

How to chat with this paper? Illustrated guide

Compare with the PDF

You can also chat with multiple papers at once here.

AI assistant instructions?

Tools for this paper

Explain it differently 1 free rewrite left today

Save to a collection Group papers in collections to compare them, chat with them and export them. Continue with Google Create a free account Log in

Export BibTeX · RIS (Zotero, Mendeley, EndNote) · Obsidian (Markdown) · Notion (Markdown) · Guides: Obsidian, Notion

Advanced tools Premium

For researchers who follow a field closely: citation alerts, journal-club slides, version comparison and Zotero export. Discover Premium

Zotero Zotero guide

Citation alerts Citation alerts guide

Who works on it? The people and institutions who publish on its topic

Journal club Premium+ Slides to present it Propose for the journal club Journal club guide

Versions What changed between versions Versions guide

Talk about it in public Premium+ Press kit: release, questions, hype check Press kit guide

Papers around this one

See them on a map

Ranked by how close their title and abstract are to this paper’s. Select some to read them together.

Closest papers

Close Same question
JWST/NIRCam Coronagraphic Search for Hidden Planets in the HD~163296 Protoplanetary Disk
Taichi Uyama, Luca Ricci, Marie Ygouf et al. · 2025 · Earth and Planetary Astrophysics · cited 6 times · AI summary available

The HD 163296 study uses JWST/NIRCam coronagraphy to search for young planets and assess point-source candidates around a nearby star system.

Abstract
HD~163296 is a Herbig Ae/Be star with multiple signposts of on-going planet formation on its disk, such as prominent rings and gaps, as well as kinematic features as identified by previous ALMA observations. We carried out JWST/NIRCam coronagraphic imaging using the F410M and F200W NIRCam filters, with the goal of detecting the emission from the putative young planets in this system. Our F410M observations did not detect the putative planets at the predicted locations of the ALMA velocity kinks, but detected a point-like source candidate at a separation of $\approx0\farcs75$ and a position angle of $\approx231\fdg4$ that is unlikely a background star because of the measured flux in the F410M…
Close Same question
Investigating the young Solar System analog HD95086
G. Chauvin, R. Gratton, M. Bonnefoy et al. · 2018 · Earth and Planetary Astrophysics · cited 34 times · AI summary available

The HD95086 study searches for and characterizes planets around a young nearby star using direct imaging and radial-velocity observations.

Abstract
HD95086 (A8V, 17Myr) hosts a rare planetary system for which a multi-belt debris disk and a giant planet of 4-5MJup have been directly imaged. Our study aims to characterize the physical and orbital properties of HD95086b, search for additional planets at short and wide orbits and image the cold outer debris belt in scattered light. We used HARPS at the ESO 3.6m telescope to monitor the radial velocity of HD95086 over 2 years and investigate the existence of giant planets at less than 3au orbital distance. With the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE at VLT, we imaged the faint circumstellar environment beyond 10au at six epochs between 2015 and 2017. We …
Close Broader context
The Direct Mid-Infrared Detectability of Habitable-zone Exoplanets Around Nearby Stars
Zach Werber, Kevin Wagner, Daniel Apai · 2022 · Earth and Planetary Astrophysics · cited 5 times · AI summary available

The detectability study models which nearby stars and planet masses could be observed directly, including with future high-sensitivity telescopes.

Abstract
Giant planets within the habitable zones of the closest several stars can currently be imaged with ground-based telescopes. Within the next decade, the Extremely Large Telescopes (ELTs) will begin to image the habitable zones of a greater number of nearby stars with much higher sensitivity$-$ potentially imaging exo-Earths around the closest stars. To determine the most promising candidates for observations over the next decade, we establish a theoretical framework for the direct detectability of Earth$-$ to super-Jovian-mass exoplanets in the mid-infrared based on available atmospheric and evolutionary models. Of the 83 closest BAFGK type stars, we select 37 FGK type stars within 10 pc and …
Close Broader context
Atmospheric Retrieval of L Dwarfs: Benchmarking Results and Characterizing the Young Planetary Mass Companion HD 106906 b in the Near-Infrared
Arthur D. Adams, Michael R. Meyer, Alex R. Howe et al. · 2023 · Earth and Planetary Astrophysics · cited 9 times · AI summary available

The HD 106906 b study characterizes a young planetary-mass companion’s atmosphere rather than searching for planets around its host star.

Abstract
We present model constraints on the atmospheric structure of HD 106906 b, a planetary-mass companion orbiting at a ~700 AU projected separation around a 15 Myr-old stellar binary, using the APOLLO retrieval code on spectral data spanning 1.1-2.5 $\mu$m. C/O ratios can provide evidence for companion formation pathways, as such pathways are ambiguous both at wide separations and at star-to-companion mass ratios in the overlap between the distributions of planets and brown dwarfs. We benchmark our code against an existing retrieval of the field L dwarf 2M2224-0158, returning a C/O ratio consistent with previous fits to the same JHKs data, but disagreeing in the thermal structure, cloud properti…
Close Another approach to the problem
Exoplanets in reflected starlight with dual-field interferometry: A case for shorter wavelengths and a fifth Unit Telescope at VLTI/Paranal
S. Lacour, Ó. Carrión-González, M. Nowak · 2024 · Earth and Planetary Astrophysics · cited 7 times · AI summary available

The interferometry study evaluates a ground-based method for directly observing cold and temperate planets, complementing coronagraphic imaging.

Abstract
The direct observation of cold and temperate planets within 1 to 10 AU would be extremely valuable for uncovering their atmospheric compositions but remains a formidable challenge with current astronomical methods. Ground-based optical interferometry, capable of high angular-resolution imaging, offers a promising avenue for studying these exoplanets, complementing space-based observations. Our objective is to explore the fundamental limits of dual-field interferometry and assess its potential for characterizing exoplanets in reflected light using the Very Large Telescope Interferometer (VLTI). We developed analytical expressions to describe the performance of dual-field interferometry and in…
Close Another approach to the problem
Efficiently Imaging Accreting Protoplanets from Space: Reference Star Differential Imaging of the PDS 70 Planetary System using the HST/WFC3 Archival PSF Library
Aniket Sanghi, Yifan Zhou, Brendan P. Bowler · 2021 · Earth and Planetary Astrophysics · cited 19 times · AI summary available

The PDS 70 study applies reference star differential imaging to HST data to recover an accreting planet, rather than using JWST coronagraphy.

Abstract
Accreting protoplanets provide key insights into how planets assemble from their natal protoplanetary disks. Recently, Zhou et al. (2021) used angular differential imaging (ADI) with Hubble Space Telescope's Wide Field Camera 3 (HST/WFC3) to recover the young accreting planet PDS 70 b in F656N ($\mathrm{H}\alpha$) at a S/N of 7.9. In this paper, we demonstrate a promising approach to efficiently imaging accreting planets by applying reference star differential imaging (RDI) to the same dataset. We compile a reference library from the database of WFC3 point-spread functions (PSFs) provided by Space Telescope Science Institute and develop a set of morphology-significance criteria for pre-selec…
Close Same question
Planet Search with the Keck/NIRC2 Vortex Coronagraph in Ms-band for Vega
Bin B. Ren, Nicole L. Wallack, Spencer A. Hurt et al. · 2023 · A&A 670, A162 (2023) · cited 5 times · AI summary available

The Vega study uses mid-infrared coronagraphic imaging to set direct-imaging planet limits around a nearby star.

Abstract
Gaps in circumstellar disks can signal the existence of planetary perturbers, making such systems preferred targets for direct imaging observations of exoplanets. Being one of the brightest and closest stars to the Sun, the photometric standard star Vega hosts a two-belt debris disk structure. Together with the fact that its planetary system is being viewed nearly face-on, Vega has been one of the prime targets for planet imaging efforts. Using the vector vortex coronagraph on Keck/NIRC2 in Ms-band at 4.67 $\mu$m, we report the planet detection limits from 1 au to 22 au for Vega with an on-target time of 1.8 h. We reach a 3 Jupiter mass limit exterior to 12 au, which is nearly an order of ma…
Close Groundwork for this paper
JWST/NIRCam Coronagraphy: Commissioning and First On-Sky Results
Julien H. Girard, Jarron Leisenring, Jens Kammerer et al. · 2022 · Instrumentation and Methods for Astrophysics · cited 51 times · AI summary available

The commissioning study describes JWST/NIRCam coronagraphy and its capabilities for detecting faint, cool exoplanets.

Abstract
In a cold and stable space environment, the James Webb Space Telescope (JWST or "Webb") reaches unprecedented sensitivities at wavelengths beyond 2 microns, serving most fields of astrophysics. It also extends the parameter space of high-contrast imaging in the near and mid-infrared. Launched in late 2021, JWST underwent a six month commissioning period. In this contribution we focus on the NIRCam Coronagraphy mode which was declared "science ready" on July 10 2022, the last of the 17 JWST observing modes. Essentially, this mode will allow to detect fainter/redder/colder (less massive for a given age) self-luminous exoplanets as well as other faint astrophysical signal in the vicinity of any…

Go further

How are these papers found?

We compare the title and abstract of this paper with those of every paper summarized on this site, and with the papers Semantic Scholar recommends, those it cites and those citing it (for a much-cited paper, its most recent citations and, from OpenAlex, the most cited ones). Among the prior work and the follow-ups, the papers that use each other in depth, a method it uses and the much-cited follow-ups come a little higher. The levels (very close, close, related) come from the similarity of the texts, not from a judgment of quality; * marks a paper without an abstract, compared by its title. The sentence under a paper is written by an AI from the two abstracts: check it in the papers. A paper marked not relevant by three readers leaves the list.

Updated on 11 November 2026.

The illustrated guide to the papers around a paper

Disclaimer: The AI-based summarization tool and virtual assistant provided on this website may not always provide accurate and complete summaries or responses. We encourage you to carefully review and evaluate the generated content to ensure its quality and relevance to your needs.

Searching for Planets around Altair with JWST/NIRcam

The essentials

Question

Method

Findings

Limitations

Why it matters

Read further

Definitions

JWST Finds No Confirmed Planets Around Altair—but Shows What It Could Detect

Looking for faint companions

How sensitive were the observations?

Background stars, not planets

A useful target for future observations

Ask questions about this paper to our AI assistant

Tools for this paper

Advanced tools Premium

Papers around this one

Closest papers

Go further

Cite this paper (BibTeX)