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Planets, Planets Everywhere (Not Just Where You'd Think)

Editor’s note: AAS Nova is on vacation until 22 September. Normal posting will resume at that time; in the meantime, we’ll be taking this opportunity to look at a few interesting AAS journal articles that have recently been in the news or drawn attention.

microlensing diagram

A diagram of how planets are detected via gravitational microlensing. The detectable planet is in orbit around the foreground lens star. [NASA]

Most of the exoplanets we’ve discovered are located within about 3,300 light-years of Earth, leaving the distribution of planets across the rest of the Milky Way a mystery. To tackle this question, a team of astronomers led by Naoki Koshimoto (NASA Goddard Space Flight Center) analyzed observations of 28 planets discovered with gravitational microlensing — a technique that can detect planets at far greater distances than the transit or radial-velocity techniques. They compared the characteristics of the observed microlensing events against what would be expected if planets tend to be clustered near the galactic center, sequestered on the edges of the galactic disk, or distributed more evenly throughout the Milky Way.

Based on the observations, the team found that planet frequency is only weakly dependent upon distance from the galactic center. This result suggests that planets are likely to be found throughout the galaxy, though the results don’t fully rule out the possibility that planets could be rare near the galactic center — especially if the masses of the lensing objects tend to be small. As the number of planets discovered with gravitational microlensing grows, astronomers should gain a better understanding of how planets are distributed throughout the Milky Way.

Original article: “No Large Dependence of Planet Frequency on Galactocentric Distance,” N. Koshimoto et al 2021 ApJL 918 L8. doi:10.3847/2041-8213/ac17ec

Osaka University press release: Cold Planets Exist Throughout Our Galaxy, Even in the Galactic Bulge

Heavy Metals Hint at an Unusually Dense White Dwarf

Editor’s note: AAS Nova is on vacation until 22 September. Normal posting will resume at that time; in the meantime, we’ll be taking this opportunity to look at a few interesting AAS journal articles that have recently been in the news or drawn attention.

A team of astronomers led by Yuken Ohshiro (University of Tokyo) used X-ray observations from the space-based XMM-Newton observatory to detect the presence of heavy metals in supernova remnant 3C 397. They discovered a region that is rich in titanium and chromium in addition to the more commonly found manganese, iron, and nickel. The ratios of the abundances of these elements suggest that they formed in a white dwarf with a central density of 5 x 109 g cm-3, which is more than twice as dense as expected for a white dwarf at the Chandrasekhar mass limit — the maximum mass white dwarfs are thought to be able to attain.

This finding suggests that the white dwarfs that give rise to Type Ia supernovae are not identical, instead having a range of central densities. Because Type Ia supernovae are considered standard candles — cosmic beacons of equal luminosity that allow us to gauge distances to far-off galaxies — it’s crucial to understand whether their white-dwarf progenitors are as uniform as expected. Extending this measurement technique to other supernova remnants should clarify our understanding of these objects and ensure that Type Ia supernovae can continue to be used as precise standard candles in the future.

Original article: “Discovery of a Highly Neutronized Ejecta Clump in the Type Ia Supernova Remnant 3C 397,” Yuken Ohshiro et al 2021 ApJL 913 L34. doi:10.3847/2041-8213/abff5b

JAXA Institute of Space and Astronautical Science press release: A rogue in the “Cosmic Standard Candle”? The relic of the densest white dwarf has been detected in the remnant of its supernova

Illustration of a compact star with beams of light emitting from its poles.

Editor’s note: AAS Nova is on vacation until 22 September. Normal posting will resume at that time; in the meantime, we’ll be taking this opportunity to look at a few interesting AAS journal articles that have recently been in the news or drawn attention.

What’s inside the dense interior of a neutron star, the remnant left behind at the end of a massive star’s evolution? Scientists have now searched for the answer to this question using new observations of an extreme neutron star from NASA’s Neutron star Interior Composition Explorer (NICER).

schematic illustrating the different layers of a neutron star, including an unknown inner core

Scientists think neutron stars are layered. As shown in this illustration, the state of matter in their inner cores remains mysterious. [NASA’s Goddard Space Flight Center Conceptual Image Lab]

Neutron star J0740+6620 is the heaviest neutron star that’s been precisely measured — and correspondingly precise measurements of its radius could provide the key to finally figuring out what its interior structure looks like. In a set of recent studies, one led by Cole Miller (University of Maryland) and the other by Thomas Riley (University of Amsterdam), two teams of scientists used NICER’s X-ray observations of J0740 to obtain accurate measures of the star’s radius using two different approaches. They found that J0740’s 2.1 solar masses are packed into a sphere just 25–27 km across.

These new results, combined with previous measurements of other neutron stars, are helping us to understand whether neutron stars are made up primarily of neutrons in their interior, or whether the pressure is so great that those neutrons have disintegrated into a soup of particles called quarks. A study led by Geert Raaijmakers (University of Amsterdam) uses these observations to place significant constraints on the so-called neutron star equation of state, which describes neutron star interiors.

To learn even more about this work, be sure to check out the summary video from NASA’s Goddard Space Flight Center below.

Original articles:
“The Radius of PSR J0740+6620 from NICER and XMM-Newton Data,” M. C. Miller et al 2021 ApJL 918 L28. doi:10.3847/2041-8213/ac089b
“A NICER View of the Massive Pulsar PSR J0740+6620 Informed by Radio Timing and XMM-Newton Spectroscopy,” Thomas E. Riley et al 2021 ApJL 918 L27. doi:10.3847/2041-8213/ac0a81
“Constraints on the Dense Matter Equation of State and Neutron Star Properties from NICER’s Mass–Radius Estimate of PSR J0740+6620 and Multimessenger Observations,” G. Raaijmakers et al 2021 ApJL 918 L29. doi:10.3847/2041-8213/ac089a

Press releases:
University of Maryland: NASA’s NICER Probes the ‘Squeezability’ of Neutron Stars
University of Amsterdam: Astronomers Measure Heaviest Known Neutron Star With Telescope on ISS

Photograph taken at night showing three radio dishes in part of an array.

Editor’s note: AAS Nova is on vacation until 22 September. Normal posting will resume at that time; in the meantime, we’ll be taking this opportunity to look at a few interesting AAS journal articles that have recently been in the news or drawn attention.

A team of scientists has used the Giant Metrewave Radio Telescope (GMRT) to measure the amount of atomic hydrogen gas — the main fuel for star formation — in galaxies at redshifts of z = 1.18–1.39, or roughly 9 billion years ago. Led by Aditya Chowdhury (National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, India), the team obtained sensitive observations of these distant galaxies with the upgraded GMRT, an array of thirty 45-meter radio dishes located in India.

Star formation activity in our universe is known to have peaked around 8–10 billion years ago before declining steadily thereafter. By probing atomic hydrogen gas 9 billion years ago — the earliest epoch for which we’ve made these measurements yet — Chowdhury and collaborators showed that galaxies at this time contained vast reservoirs of fuel. This outcome supports the idea that our universe’s declining star formation is tied to depletion of these fuel reserves.

Original article: “Giant Metrewave Radio Telescope Detection of Hi 21 cm Emission from Star-forming Galaxies at z ≈ 1.3,” Aditya Chowdhury et al 2021 ApJL 913 L24. doi:10.3847/2041-8213/abfcc7

National Centre for Radio Astrophysics, Tata Institute of Fundamental Research press release:
GMRT Measures the Atomic Hydrogen Gas Mass in Galaxies 9 Billion Years Ago

Five images show different gas velocity components of an elliptical protoplanetary disk surrounding a young star.

Editor’s note: AAS Nova is on vacation until 22 September. Normal posting will resume at that time; in the meantime, we’ll be taking this opportunity to look at a few interesting AAS journal articles that have recently been in the news or drawn attention.

Scientists have made a new, unusually accurate measurement of the mass of the protoplanetary disk orbiting around the young star Elias 2–27. The masses of protoplanetary disks — the disks of gas and dust that surround young stars, in which planets form — are highly uncertain. This inability to precisely measure how much matter is available to form baby planets limits our ability to understand the planet formation processes, so better means of measuring disk masses are needed.

In a new study led by Benedetta Veronesi (University of Milan, Italy), a team of scientists has now leveraged multiwavelength observations from the Atacama Large Millimeter/submillimeter Array (ALMA) to track the rotation curve of the disk around Elias 2–27, disentangling the gravitational influence of the central star from the self-gravity of the disk. This allowed the team to make the first dynamical measurement of this protoplanetary disk’s mass — which provides a much more accurate measurement than previous methods and lays the groundwork for extending this technique to other systems.

Original article: “A Dynamical Measurement of the Disk Mass in Elias 2–27,” Benedetta Veronesi et al 2021 ApJL 914 L27. doi:10.3847/2041-8213/abfe6a

National Radio Astronomy Observatory (NRAO) press release:
Study of Young Chaotic Star System Reveals Planet Formation Secrets

Gif animation shows different views of the disk around Elias 2-27 at different wavelengths

This animation shows the different molecular tracers used to better understand the gases present in the disk surrounding Elias 2-27. Seen are the 0.87 mm dust continuum data (blue), C18O emission (yellow), and 13CO emission (red), with each layer shown individually and in composite. [T. Paneque-Carreño, NRAO/AUI/NSF, B. Saxton; CC BY 4.0]

Illustration of an enormous loop of plasma erupting from the surface of a dim, red star.

Editor’s note: AAS Nova is on vacation until 22 September. Normal posting will resume at that time; in the meantime, we’ll be taking this opportunity to look at a few interesting AAS journal articles that have recently been in the news or drawn attention.

Astronomers have observed the largest stellar flare ever recorded from Proxima Centauri, our nearest stellar neighbor. Detected in May 2019, the flare was recently reported in a publication led by scientist Meredith MacGregor (University of Colorado Boulder). During the flare, MacGregor and collaborators observed Proxima Centauri to brighten by a factor of more than 1,000 in millimeter emission, and by a factor of more than 14,000 in ultraviolet emission.

Studying the combination of these flare signals helps us to better understand what triggers these powerful flashes and how they evolve. This, in turn, provides valuable information about the radiation environment surrounding rocky, inner planets — planets like Proxima Centauri b, which lies in Proxima Centauri’s habitable zone but may be at risk of being cooked by bright and energetic flares from its host.

Original article: “Discovery of an Extremely Short Duration Flare from Proxima Centauri Using Millimeter through Far-ultraviolet Observations,” Meredith A. MacGregor et al 2021 ApJL 911 L25. doi:10.3847/2041-8213/abf14c
University of Colorado Boulder press release: Humongous flare from sun’s nearest neighbor breaks records

Photograph of a female speaker at a podium next to a row of seated panelists behind a banner that reads "American Astronomical Society"

We’re delighted to (re-)introduce Kerry Hensley, a planetary scientist who has recently joined the AAS staff as our Communications Specialist. You can expect to see Kerry in person at future AAS meetings in her capacity as the AAS Deputy Press Officer. In addition, Kerry will serve as co-editor of AAS Nova — so you’ll be seeing her byline on research highlights in the near future!

Photograph of Kerry Hensley, the new AAS Communications Specialist

AAS Communications Specialist Kerry Hensley

Kerry is not new to the AAS’s ranks: You may remember her from her term as the inaugural AAS Media Fellow (a quarter-time position for graduate students in the astronomical sciences who wish to cultivate their science communication skills, a position currently held by Tarini Konchady). Over the span of her 1.5-year fellowship term, Kerry helped to plan and run press conferences at AAS meetings, assisted in operating the AAS press release distribution service, and wrote and published articles here on AAS Nova.

Since concluding her fellowship term at the AAS, Kerry was selected as an American Association for the Advancement of Science (AAAS) Mass Media Science and Engineering Fellow and served as a science journalist for Voice of America, writing articles and scripting, voicing, and producing radio and video stories. Her past science communication pursuits include freelance writing (with bylines in publications like Sky & Telescope magazine), presenting planetarium shows, and writing and editing for Astrobites.

Kerry earned her BA in astrophysics and Chinese at Williams College and will shortly defend her PhD dissertation work in planetary atmospheres at Boston University. We’re excited to welcome her on board!

Orange banner containing the open access logo, a stylized open lock.

We usually don’t put exclamation points in titles around here, but we’re really excited about this one. As of 1 January 2022, all AAS journals will officially be open access (OA) — which means that anyone can read, download, and share the content in them with no subscription charge. We think this is a huge and important step in our efforts to increase equity and the sharing of knowledge in astronomy, and we hope that you agree!

For the full details about this change, you can read our press release and our detailed FAQ. And if you’re new to the world of academic publishing, check out CfA/AAS Innovation Scientist Peter Williams’s excellent — and honest — summary of the scene and how AAS’s move to OA fits in.

Here, we’ll just briefly outline this transition and a few of its implications so you can see how this might impact you as a member of the astronomy community.

Wait, What’s Happening?

After 1 January 2022, all AAS journals will transition to an open access model. This means no more subscriptions, paywalls, or access control on any past, present, or future AAS journals content after 31 December 2021.

images of the covers of the six aas journals with open access logos superposed on each

All AAS journals will be open access on 1 January 2022.

The transition will apply to the Astronomical Journal (AJ), the Astrophysical Journal (ApJ), Astrophysical Journal Letters (ApJL), and the Astrophysical Journal Supplement Series (ApJS); the Planetary Science Journal (PSJ) and Research Notes of the AAS (RNAAS) are both already open access.

A Little Background on the Business

Until recently, most scholarly journals have been 100% supported by institutional subscriptions: institutes pay so their researchers can read articles in the journals. This model has the benefit of allowing authors to publish without charge — but it has the significant downside of limiting who is able to see that research.

AAS has relied for decades on a hybrid model, in which ~1/3 of journal revenue comes from institutional subscriptions and ~2/3 from article publication charges. This helps distribute the financial burden better and reduces the time that articles are paywalled (only 12 months after publication).

The move to fully open access — in which article publication charges will represent 100% of the support for the journals — takes this a step further. Under an open access model, no amount of the financial burden falls to the reader, and anyone is able to see the research in AAS journals immediately upon publication.

Hang On, What About the Authors?

At this point, you may be wondering: We’re removing the barrier to accessing the research in our journals — but doesn’t this just introduce a new barrier to publishing it?

We want to avoid that, which is why we’ve introduced a significantly expanded waiver budget into our new pricing model. Authors who don’t have the funds to publish with us can apply for a waiver of article publication charges, and the Editor in Chief can authorize waivers based on need.

That said, authors who do have the funds to publish with us are expected to pull their weight! We did our best to get the costs as low as possible while still covering the loss of subscription revenue and the increased waiver budget. We hope that the community will see this transition to OA as a positive move toward increased inclusivity, and that those who can afford it will continue to step up — as they’ve already done for decades — to pay their share and help ensure that anyone who wants to submit to AAS journals can, regardless of financial situation.

What This Transition Means for You

If you’re an amateur astronomer or enthusiast, this change should give you the freedom to more easily pursue your interests. Ever been annoyed when you’ve followed the link to a really awesome-sounding article and gotten stuck at a paywall? That won’t happen with us anymore. After 1 January 2022, be ready to dive into any exciting astronomy that catches your eye.

If you’re a researcher who publishes with AAS journals, know that after 1 January 2022, your article will be immediately available for anyone in the world to read. Page charges will likely be a little higher, but that money’s going toward making science an inclusive and open enterprise. And our data shows that, statistically, your open-access work will be even more likely to be cited and downloaded, which is a nice perk.

And if you’re a researcher who doesn’t publish with AAS journals, well — what better time to start?

Ultimately, the upcoming transition to our new model won’t change the high-quality research published in the AAS journals. It just removes the barriers to who can create, discover, share, and build on that research — in short, who can participate in astronomy. And that’s an outcome we hope everyone can be excited about.

Photograph of a female speaker at a podium next to a row of seated panelists behind a banner that reads "American Astronomical Society"

Are you an astronomy graduate student who’s interested in science communication? Do you wish you had the opportunity to explore that interest and gain professional development without having to take time off from your graduate studies? Do you want to write for AAS Nova, report on astronomy meetings, and help organize and run press conferences?

Then the AAS Media Fellowship might be for you! This position was developed in 2017 by the American Astronomical Society to provide training and experience for a graduate student in the astronomical sciences interested in science communication. The fellowship is a remote, quarter-time, one year (with the possibility of extension to two years) position intended to be filled by a current graduate student at a US institution. The new AAS Media Fellowship term will begin in Fall 2021.

If this sounds like a good fit for you, you can get more information below or at the job register posting. Apply by 23 July 2021 by submitting your contact information, advisor approval, a cover letter, and a short CV to personnel@aas.org. See the job register posting for the full application details.

Essential Duties & Responsibilities

The AAS Media Fellow will report to the AAS Communications Manager. The Fellow will work the equivalent of one day per week (on a schedule that will be jointly developed and agreed upon by the Fellow, the AAS Communications Manager, and the AAS Communications Specialist) and be responsible for a wide range of duties. The Fellow will be expected to:

  • Assist in sharing astronomy press releases via AAS Press Office channels.
  • Regularly write and publish articles for AAS Nova.
  • Occasionally help to prepare other written communications such as AAS or Division press releases.
  • Assist in managing AAS communications such as social media accounts, postings to the AAS website, and emails to members or authors.
  • Serve as backup to the AAS Communications Manager or the AAS Communications Specialist during absences.
  • At the AAS winter and summer meetings, help the AAS Communications Manager plan and run press conferences, help represent AAS Nova, and help organize live-blogging coverage of the meeting for Astrobites and AAS Nova.

Qualifications

The Fellow must:

  • Be a graduate student in good standing in the astronomical sciences or a related field at a U.S. institution.
  • Receive the approval of their advisor or department chair to apply.
  • Receive their primary support from their home institution.
  • Have a keen eye for detail and accuracy.
  • Have the ability to absorb complex material, synthesize information, and write short articles that concisely reflect key points of the material to a target audience.
  • Have good working knowledge of, and/or ability to quickly master, tools such as WordPress, Drupal, Microsoft Office, and Adobe Creative Suite.

Compensation

The stipend for this position is $7,500 per year for the equivalent of one day of work per week; payable on a quarterly basis. Travel support will also be provided for travel to the summer and winter AAS meetings.

BlackLivesMatter logo of an upheld, closed fist, superposed on a photograph of the Milky Way.

The American Astronomical Society office will be closed today in observance of the newly established federal holiday, Juneteenth. As we recognize this day that celebrates the emancipation of enslaved African Americans, it’s also important that we look to the future. How can we continue to work to eradicate anti-Black racism in the astronomy community, and how can we better support Black astronomers?

Instead of our usual highlight today, we are sharing a few resources from our partner Astrobites, the Black in Astro team, and the Black in Physics team. We hope you’ll take this opportunity to learn more about Black experiences in space- and astronomy-related fields and help to celebrate and amplify them!

#BlackInAstro Series on Astrobites

This series, a collaboration between Astrobites and the Black In Astro community, is ongoing; you can check the the #BlackinAstro tag on the astrobites website for new posts.

  1. #BlackInAstro: How Can We Support Black Astronomers? by Astrobites (3 Jun 2020)
  2. #BlackInAstro: Black Representation in Astro/Physics and the Impact of Discrimination by Astrobites (12 Jun 2020)
  3. #BlackInAstro Experiences: KeShawn Ivory by KeShawn Ivory (19 Jun 2020)
  4. 1981: Barbara Williams becomes the first Black woman to get a PhD… by Jessica May Hislop (20 Jun 2020)
  5. #BlackInAstro Experiences: Ashley Walker by Mia de los Reyes (22 Jun 2020)
  6. #BlackInAstro: Not a Lack of Science Aspiration, But a Lack of Career Inspiration? by Luna Zagorac (23 Jun 2020)
  7. #BlackInAstro Experiences: Cheyenne Polius by Cheyenne Polius (24 Jun 2020)
  8. #BlackInAstro: Black Women in Astronomy and Physics by Kate Storey-Fisher (25 Jun 2020)
  9. #BlackInAstro Experiences: David Zegeye by David Zegeye (26 Jun 2020)
  10. #BlackInAstro Experiences: Ayanna Jones by Mia de los Reyes (27 Jun 2020)
  11. #BlackInAstro: A Glimpse Into African Cultural Astronomy by Briley Lewis (28 Aug 2020)
  12. #BlackInAstro Experiences: Dr. Greg Mosby by Briley Lewis (26 Oct 2020)
  13. #BlackInAstro Experiences: Dr. Sian Proctor by Briley Lewis (28 Oct 2020)
  14. #BlackInAstro Experiences: Katrina Miller by Mia de los Reyes (30 Oct 2020)
  15. #BlackInAstro: AAS237 Special Session on Anti-Blackness in Astronomy by Gourav Khullar (7 Feb 2021)
  16. #BlackInAstro Experiences: Dr. Jarita Holbrook by Luna Zagorac (26 Feb 2021)
  17. #BlackInAstro Experiences: Moiya McTier by Sabina Sagynbayeva (19 Mar 2021)
  18. #BlackInAstro Unsung Heroes: Crystal Tinch by guest author Katrina Miller (16 Apr 2021)
  19. #BlackInAstro Experiences: Dr. Tana Joseph by Ellis Avallone (7 May 2021)

Juneteenth #BlackInPhysics Wikipedia Edit-a-Thon

APS/Black in Physics banner that reads "Juneteenth Freedom Day Edit-a-thon Sunday June 20" and has images of the Wikipedia, APS, and Black in Physics logos.Celebrate Juneteenth Freedom Day with the American Physical Society and @BlackinPhysics by attending a Wikipedia edit-a-thon on Sunday, June 20, 12:00–3:00 p.m. ET, where we’ll be creating & editing Wikipedia pages about Black physicists. Anyone is welcome to attend. Sign up today! https://go.aps.org/2Re7iEu

#BlackInAstro Week

June 20–26 is Black in Astro Week 2021! Join the Black in Astro community in celebrating and amplifying Black experiences in astronomy- and space-related fields in a week of events, panels, and more at BlackInAstro.com and on Twitter. The schedule and themes for each day of the week are listed below; you can sign up for events and find out more at BlackInAstro.com.

Sunday June 20 – #BlackInAstroGrandSlam
  • 4:00–6:00 pm EST: Come Meet the Black In Astro Team, watch performances, and B.Y.O.B (Bring Your Own Beverage) for a chill and fun night with prizes
Monday June 21 – #BlackXploration
  • Celebrate all things Aerospace, Astronauts, Aeronautics, Astronautics, and more! Share your stories/research with the hashtags #BlackInAeroRollCall & #BlackXploration
  • 6:00–7:30pm EST: Launching a Career Into Space: A Discussion about Aerospace Careers/Journey
  • Enter the giveaway for a chance to win one of three lego sets for kids!
Tuesday June 22 – #BlackToTheFuture
  • Celebrate with us as we dedicate this day to afrofuturism, art, astrophotography, and more — featuring special prizes!
  • Submit your astro-themed artwork for a chance to win some amazing prizes from ceramic artist, Amy Rae Hill, a $25.00 gift card from STARtoralist, and postcards from Dr. Sian Proctor.
  • Enter the giveaway for a chance to win one of two copies of Ytasha Womack’s book – Afrofuturism
  • 12:00–1:00 pm EST: Alien vs Predator/SKA Telescope Live Discussion with Dr. Tana Joseph Watch here (co-hosted by The SETI Institute)
Wednesday June 23 – #AstroWorld
  • Join us for an out of this world day dedicated to exoplanets, atmospheres, planet formation, and planetary sciences. Use the hashtag #AstroWorldRollCall to introduce yourself.
  • Join us on Instagram and Twitter as we takeover the SETI pages for a day full of fun facts and trivia
Thursday June 24 – #BlackWhole
  • Join us for a day filled with poetry and featuring Black Holes, Dark Matter, Galaxies and Gravitational Waves! Use the hashtag #BlackWholeRollCall to introduce yourself and share your research
  • Summarize research using a haiku for a chance to win a $30.00 gift card and other special prizes
  • Join our founder and co-organizer Ashley Lindalia & Dakotah Tyler for a special SETI Live event
Friday June 25 – #AllTheStars
  • All the stars are closer. Join us as we celebrate Black influences on the Black Space Family Members and let’s talk about some ISM and stars
  • Use the hashtag #AllTheStarsRollCall to introduce yourself and tell your story of who influenced you in the space sciences
Saturday June 26 – #BlackSpace
  • Let’s talk about Black scicommers and educators. Join us for a day filled with science communication knowledge
  • Use the hashtag #BlackSpaceRollCall to introduce yourself
  • Special video premiere
  • Join us for trivia night with a special prize giveaway
Poster describing the events of the BlackinAstro Week 2021. See article text for details.

#BlackInAstro Week 2021 schedule, from blackinastro.com.

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