Category Archives: Results

Here are brief descriptions of scientific results obtained with MagAO, Clio, and VisAO. At the end of each you will find links to the science paper, including freely downloadable preprints.

MagAO helped identify the progenitor of SN 2016adj

It is rare for MagAO to carry out extragalactic observations because suitable natural guide stars are hard to find.

But this time we have got some luck. A week ago (February 8), a bright supernova, SN 2016adj, appeared in the active galaxy NGC 5128 (Centaurus A). Classified as Type IIb, its progenitor is believed to be a very massive star in a binary system, undergoing a significant mass loss before explosion. However, direct identification of the progenitor remains challenging, even though astronomers have been constantly detecting supernovae in imaging surveys.

Since SN 2016adj is only 4″ from a bright foreground star, it is an ideal target for our visible AO camera. Prompted by Prof. Nathan Smith, we used MagAO to observe the supernova on February 13, and successfully took ~2 hr deep exposures at 0.9 micron. Comparing the new MagAO image to archival HST and VLT data, we and our collaborators were able to identify a possible progenitor star. Notably, this is the 5th Type IIb progenitor identified in pre-explosion images over the past 20 years.

We used MagAO to identify the progenitor star in this pre-explosion image taken by the Hubble Space Telescope.

We used MagAO to identify the progenitor star in this pre-explosion image taken by the Hubble Space Telescope.

Yesterday we posted our results on the Astronomer’s Telegram. You can find the link here:
http://www.astronomerstelegram.org/?read=8693

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The Birds and The Bees of Planet Formation

MagAO’s revolutionary visible light capabilities have allowed us to directly image a planet residing inside a circumstellar disk gap for the first time. These images, of the forming protoplanet LkCa 15 b, provide the first incontrovertible evidence of accretion onto a forming planet.

In fact, the study joined two independent results from Arizona facilities – interferometric data from the Large Binocular Telescope on Mt. Graham in Arizona and direct images from our very own MagAO system at Las Campanas Observatory in Chile.

The MagAO data was obtained by myself (Kate Follette), Laird Close, Jared Males, and Katie Morzinski as part of the Giant Accreting Protoplanet Survey (GAPplanetS). The final product: images of the forming protoplanet LkCa15b glowing in the light of ultra hot hydrogen gas. This is an indication that the planet is still growing, because Hydrogen gas glows at this characteristic wavelength of light when it is in the process of falling onto a massive object – in this case a protoplanet! LkCa15 b is visible glowing in Hydrogen-alpha, but unlike our previous discovery of HD142527B, it is NOT glowing in ordinary visible light. This indicates that the underlying object is very low mass – the first true GAPplanet!

LkCa15_StanfordPR_v2

Read about the entire study, which combined our H-alpha data with near-infrared interferometric data from the Large Binocular Telescope collected by Steph Sallum and Josh Eisner, at the links below. Steph and Josh were able to isolate light from two more protoplanet candidates – LkCa15c and d, and saw LkCa15b in the same place as the MagAO direct images, providing independent confirmation of its identity as a forming protoplanet!

LkCa15

The Nature Article

UA Press Release

Stanford Press Release

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Magellan Adaptive Optics first-light observations of the exoplanet beta Pic b. II. 3-5 micron direct imaging with MagAO+Clio, and the empirical bolometric luminosity of a self-luminous giant planet

I am happy to announce the acceptance of Magellan Adaptive Optics first-light observations of the exoplanet beta Pic b. Paper II by the Astrophysical Journal. This paper presents the 0.9-5 micron spectral energy distribution (SED) of young giant exoplanet beta Pic b. We carefully calibrated Clio (see the Appendix), analyzed our photometry, combined it with other works’ photometry, and measured the total brightness of the planet at all wavelengths — the bolometric luminosity. Here are the images of the star and planet:

Images of the star beta Pic (Left: saturated; Center: Unsaturated) and its planet beta Pic b (Right) with MagAO. In this study we analyze the photometry in order to measure the total luminosity of the planet at all wavelengths (Figure 1 from the paper).

Here is the star’s SED and the planet’s SED:

Top: SED of the star (Figure 2 from the paper).
Bottom: SED of the planet (Figure 3 from the paper).

We measured the bolometric luminosity empirically by integrating the SED and extending with a best-fit blackbody:

Empirical Bolometric Luminosity (Figure 8 from the paper).

This is the first time the luminosity has been measured empirically, and it is in agreement with the luminosity from models but about 20% brighter than brown dwarfs of a similar temperature (the bolometric correction, abbreviated B.C. in the table):

Physical parameters of the planet according to different works (Table 15 from the paper).

Abstract: Young giant exoplanets are a unique laboratory for understanding cool, low-gravity atmospheres. A quintessential example is the massive extrasolar planet beta Pic b, which is 9 AU from and embedded in the debris disk of the young nearby A6V star beta Pictoris. We observed the system with first light of the Magellan Adaptive Optics (MagAO) system. In Paper I we presented the first CCD detection of this planet with MagAO+VisAO. Here we present four MagAO+Clio images of beta Pic b at 3.1 um, 3.3 um, L’, and M’, including the first observation in the fundamental CH_4 band. To remove systematic errors from the spectral energy distribution (SED), we re-calibrate the literature photometry and combine it with our own data, for a total of 22 independent measurements at 16 passbands from 0.99-4.8 um. Atmosphere models demonstrate the planet is cloudy but are degenerate in effective temperature and radius. The measured SED now covers > 80% of the planet’s energy, so we approach the bolometric luminosity empirically. We calculate the luminosity by extending the measured SED with a blackbody and integrating to find log(L_{bol}/L_{Sun}) = -3.78 +- 0.03. From our bolometric luminosity and an age of 23 +- 3 Myr, hot-start evolutionary tracks give a mass of 12.7 +- 0.3 M_{Jup}, radius of 1.45 +- 0.02 R_{Jup}, and T_{eff} of 1708 +- 23 K (model-dependent errors not included). Our empirically-determined luminosity is in agreement with values from atmospheric models (typically -3.8 dex), but brighter than values from the field-dwarf bolometric correction (typically -3.9 dex), illustrating the limitations in comparing young exoplanets to old brown dwarfs.

K. Morzinski et al., “Magellan Adaptive Optics first-light observations of the exoplanet beta Pic b. II. 3-5 micron direct imaging with MagAO+Clio, and the empirical bolometric luminosity of a self-luminous giant planet”
ApJ 815, 108, 2015 ; ArXiv Preprint ; ApJ

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