Comments on: Lonely Planet Guide to the Hyades http://oklo.org/2007/02/09/lonely-planet-guide-to-the-hyades/ characterizing planetary systems Fri, 18 Nov 2011 22:27:52 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: systemic - The Perfect Storm http://oklo.org/2007/02/09/lonely-planet-guide-to-the-hyades/comment-page-1/#comment-2200 systemic - The Perfect Storm Sat, 21 Apr 2007 19:41:10 +0000 http://oklo.org/?p=188#comment-2200 [...] HD 185269b was discovered by John Johnson, who has been carrying out a radial velocity survey of luminous Hertzsprung-gap stars (discovery paper here). The stars in his survey are more massive than the Sun, and are in the midst of ending the core hydrogen-burning phase of their life cycles. They’re in the process of turning into red giants, and are thus cool enough to be profitably observed with the Doppler radial velocity technique. (See this post for more on John’s survey and its implications). HD 189269 is about four times more luminous than the Sun, and so the surface of the planet should average out at ~1300 K, which is quite hot, even for a hot Jupiter. [...] [...] HD 185269b was discovered by John Johnson, who has been carrying out a radial velocity survey of luminous Hertzsprung-gap stars (discovery paper here). The stars in his survey are more massive than the Sun, and are in the midst of ending the core hydrogen-burning phase of their life cycles. They’re in the process of turning into red giants, and are thus cool enough to be profitably observed with the Doppler radial velocity technique. (See this post for more on John’s survey and its implications). HD 189269 is about four times more luminous than the Sun, and so the surface of the planet should average out at ~1300 K, which is quite hot, even for a hot Jupiter. [...]

]]> By: Centauri Dreams » Blog Archive » Hyades Planet Challenges Formation Theories http://oklo.org/2007/02/09/lonely-planet-guide-to-the-hyades/comment-page-1/#comment-1249 Centauri Dreams » Blog Archive » Hyades Planet Challenges Formation Theories Wed, 21 Feb 2007 14:57:15 +0000 http://oklo.org/?p=188#comment-1249 [...] It’s an interesting world, a gas giant that’s a little less than 2 AU out and an orbital period of 1.63 years. This is the first planet discovered around a red giant, its star the most massive of all planet hosts known. That leads to intriguing speculation: Should we expect planets around other red giants, and do our current planet formation theories work in this environment? The latter point bears watching. Greg Laughlin (UC-Santa Cruz) argues that in the case of epsilon Tauri b, the cluster’s harsh ultraviolet radiation should have disrupted the protplanetary nebula. The UV radiation environment in the original Hyades cluster was fierce. The protostellar disks of the individual Hyads were likely photoevaporated before the growing planetary cores were able to reach the runaway gas accretion phase that gives rise to Jupiter-mass planets (see our paper on this topic). When we get the full inventory of planets in the Hyades, I think we’ll find plenty of Neptunes and terrestrial planets, but almost nothing in the Jovian range. Indeed, work by Bill Cochran and the Texas RV group has demonstrated that the Hyades are generally deficient in massive planets. [...] [...] It’s an interesting world, a gas giant that’s a little less than 2 AU out and an orbital period of 1.63 years. This is the first planet discovered around a red giant, its star the most massive of all planet hosts known. That leads to intriguing speculation: Should we expect planets around other red giants, and do our current planet formation theories work in this environment? The latter point bears watching. Greg Laughlin (UC-Santa Cruz) argues that in the case of epsilon Tauri b, the cluster’s harsh ultraviolet radiation should have disrupted the protplanetary nebula. The UV radiation environment in the original Hyades cluster was fierce. The protostellar disks of the individual Hyads were likely photoevaporated before the growing planetary cores were able to reach the runaway gas accretion phase that gives rise to Jupiter-mass planets (see our paper on this topic). When we get the full inventory of planets in the Hyades, I think we’ll find plenty of Neptunes and terrestrial planets, but almost nothing in the Jovian range. Indeed, work by Bill Cochran and the Texas RV group has demonstrated that the Hyades are generally deficient in massive planets. [...]

]]> By: TheoA http://oklo.org/2007/02/09/lonely-planet-guide-to-the-hyades/comment-page-1/#comment-1139 TheoA Fri, 16 Feb 2007 03:37:19 +0000 http://oklo.org/?p=188#comment-1139 Many yaers ago Hubble also probed another Globular Cluster, 47 Tucanae, and could find not hot jupiters using the transit method. I remember being profoundly saddened for it meant that planet formation was not an even or predictable process. I was also saddened as it destroyed the scientific basis for my guilty pleasure, Stargate Atlantis. Many yaers ago Hubble also probed another Globular Cluster, 47 Tucanae, and could find not hot jupiters using the transit method.

I remember being profoundly saddened for it meant that planet formation was not an even or predictable process.

I was also saddened as it destroyed the scientific basis for my guilty pleasure, Stargate Atlantis.

]]> By: mike http://oklo.org/2007/02/09/lonely-planet-guide-to-the-hyades/comment-page-1/#comment-1123 mike Sat, 10 Feb 2007 17:56:43 +0000 http://oklo.org/?p=188#comment-1123 Many years ago, the Hubble telescope found a planet in a globular cluster. See HubbleSite - NewsCenter - 2003 - 19 - Oldest Known Planet Identified.htm Many years ago, the Hubble telescope found a planet in a globular cluster. See
HubbleSite – NewsCenter – 2003 – 19 – Oldest Known Planet Identified.htm

]]> By: Vincent http://oklo.org/2007/02/09/lonely-planet-guide-to-the-hyades/comment-page-1/#comment-1121 Vincent Sat, 10 Feb 2007 12:33:36 +0000 http://oklo.org/?p=188#comment-1121 Thank you very much Eugenio for your explanations ! :-) Thank you very much Eugenio for your explanations ! :-)

]]> By: andy http://oklo.org/2007/02/09/lonely-planet-guide-to-the-hyades/comment-page-1/#comment-1120 andy Sat, 10 Feb 2007 11:00:26 +0000 http://oklo.org/?p=188#comment-1120 Thanks for the explanation. You might be able to get the less than sign by using a character escape < - testing - < Thanks for the explanation.

You might be able to get the less than sign by using a character escape &lt; – testing – <

]]> By: Eugenio http://oklo.org/2007/02/09/lonely-planet-guide-to-the-hyades/comment-page-1/#comment-1119 Eugenio Sat, 10 Feb 2007 04:54:11 +0000 http://oklo.org/?p=188#comment-1119 Hi Vincent, I finally remembered that the symbol for less than has a special meaning in html. Hopefully, it will work this time. less than ~ 15 stellar radii or less than ~ 0.04 seconds of arc (based on the star's distance of 47.5 parsecs). It's not clear how difficult it would be to detect the object this close to a star this bright. Considering the age of the Hyades (625 Myr), if it were detected in the infrared, it's brightness could help determine if it's a planet or brown dwarf. (Greg can correct me here.) I bleieve young planets and brown dwarfs cool off at different rates so that at a given early age, one will appear brighter than the other in the infrared (assuming they have the same radii). Hi Vincent,

I finally remembered that the symbol for less than has a special meaning in html. Hopefully, it will work this time.

less than ~ 15 stellar radii or less than ~ 0.04 seconds of arc (based on the star’s distance of 47.5 parsecs). It’s not clear how difficult it would be to detect the object this close to a star this bright. Considering the age of the Hyades (625 Myr), if it were detected in the infrared, it’s brightness could help determine if it’s a planet or brown dwarf. (Greg can correct me here.) I bleieve young planets and brown dwarfs cool off at different rates so that at a given early age, one will appear brighter than the other in the infrared (assuming they have the same radii).

]]> By: Eugenio http://oklo.org/2007/02/09/lonely-planet-guide-to-the-hyades/comment-page-1/#comment-1118 Eugenio Sat, 10 Feb 2007 04:48:25 +0000 http://oklo.org/?p=188#comment-1118 Hi Andy, Hopefully, I can eventually get the rest of my response to Vincent's comment on the site. I'll try to address yours here. Again, Greg can correct me or add to what's below. Two things come to mind: timing and the environment. If a (relatively low mass) star with a (relatively high mass) protoplanetary disk is ejected from a cluster before the O, B, and possibly A stars turn on (or soon there after), a planetary system could form in relative ``safety.'' If there is enough optically thick material between the stars, it could protect a forming planetary system from the intense radiation of O and B stars. When the O and B stars go supernova, the resulting shock waves may actually trigger additional star formation in the surrounding cluster material. It's also possible that some open cluster may never have had O and B stars in them. Whatever, the situation, the surving low mass stars (F,G,K, and M stars) eventually leave the cluster through dynamical escape. Those left behind have fewer and fewer neighbors over time, making it more likely that any surviving planetary systems will continue to survive. Hi Andy,

Hopefully, I can eventually get the rest of my response to Vincent’s comment on the site.

I’ll try to address yours here.

Again, Greg can correct me or add to what’s below.

Two things come to mind: timing and the environment. If a (relatively low mass) star with a (relatively high mass) protoplanetary disk is ejected from a cluster before the O, B, and possibly A stars turn on (or soon there after), a planetary system could form in relative “safety.” If there is enough optically thick material between the stars, it could protect a forming planetary system from the intense radiation of O and B stars. When the O and B stars go supernova, the resulting shock waves may actually trigger additional star formation in the surrounding cluster material. It’s also possible that some open cluster may never have had O and B stars in them. Whatever, the situation, the surving low mass stars (F,G,K, and M stars) eventually leave the cluster through dynamical escape. Those left behind have fewer and fewer neighbors over time, making it more likely that any surviving planetary systems will continue to survive.

]]> By: Eugenio http://oklo.org/2007/02/09/lonely-planet-guide-to-the-hyades/comment-page-1/#comment-1117 Eugenio Sat, 10 Feb 2007 04:25:06 +0000 http://oklo.org/?p=188#comment-1117 Hi Vincent, Here's another try: Hi Vincent,
Here’s another try:

]]> By: Eugenio http://oklo.org/2007/02/09/lonely-planet-guide-to-the-hyades/comment-page-1/#comment-1116 Eugenio Sat, 10 Feb 2007 04:23:33 +0000 http://oklo.org/?p=188#comment-1116 Hi Vincent, Here's the rest of my reply: Hi Vincent,

Here’s the rest of my reply:

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